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IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Network192.168.200.0/21
Usable hosts2,046
Subnet mask255.255.248.0
Addresses2,048
Network address
192.168.200.0
Broadcast address
192.168.207.255
First usable
192.168.200.1
Last usable
192.168.207.254
Usable hosts
2,046 (2,048 less the network and broadcast addresses)
Subnet mask
255.255.248.0
Wildcard mask
0.0.7.255 (Cisco ACLs, OSPF)
Prefix length
/21
Type
Private (RFC 1918) 192.168.0.0/16
Office and home networks; not routed on the internet
Old class
C (default /24)
As numbers
Hex C0A8C800 · Integer 3232286720 to 3232288767
Reverse DNS zones
200.168.192.in-addr.arpa
201.168.192.in-addr.arpa
202.168.192.in-addr.arpa
203.168.192.in-addr.arpa
204.168.192.in-addr.arpa
205.168.192.in-addr.arpa
206.168.192.in-addr.arpa
207.168.192.in-addr.arpa
/21 is not on a 8-bit boundary, so it takes 8 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11000000.10101000.11001000.00000000192.168.200.0
Subnet mask11111111.11111111.11111000.00000000255.255.248.0
Network11000000.10101000.11001000.00000000192.168.200.0
Broadcast11000000.10101000.11001111.11111111192.168.207.255
Split into smaller subnets/29
/22 (2)/23 (4)/24 (8)/25 (16)/26 (32)/27 (64)/28 (128)/29 (256)/30 (512)/31 (1,024)/32 (2,048)

192.168.200.0/21 makes 256 subnets of /29.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1192.168.200.0/29192.168.200.1 to 192.168.200.6192.168.200.76
2192.168.200.8/29192.168.200.9 to 192.168.200.14192.168.200.156
3192.168.200.16/29192.168.200.17 to 192.168.200.22192.168.200.236
4192.168.200.24/29192.168.200.25 to 192.168.200.30192.168.200.316
5192.168.200.32/29192.168.200.33 to 192.168.200.38192.168.200.396
6192.168.200.40/29192.168.200.41 to 192.168.200.46192.168.200.476
7192.168.200.48/29192.168.200.49 to 192.168.200.54192.168.200.556
8192.168.200.56/29192.168.200.57 to 192.168.200.62192.168.200.636
9192.168.200.64/29192.168.200.65 to 192.168.200.70192.168.200.716
10192.168.200.72/29192.168.200.73 to 192.168.200.78192.168.200.796
11192.168.200.80/29192.168.200.81 to 192.168.200.86192.168.200.876
12192.168.200.88/29192.168.200.89 to 192.168.200.94192.168.200.956
13192.168.200.96/29192.168.200.97 to 192.168.200.102192.168.200.1036
14192.168.200.104/29192.168.200.105 to 192.168.200.110192.168.200.1116
15192.168.200.112/29192.168.200.113 to 192.168.200.118192.168.200.1196
16192.168.200.120/29192.168.200.121 to 192.168.200.126192.168.200.1276
17192.168.200.128/29192.168.200.129 to 192.168.200.134192.168.200.1356
18192.168.200.136/29192.168.200.137 to 192.168.200.142192.168.200.1436
19192.168.200.144/29192.168.200.145 to 192.168.200.150192.168.200.1516
20192.168.200.152/29192.168.200.153 to 192.168.200.158192.168.200.1596
21192.168.200.160/29192.168.200.161 to 192.168.200.166192.168.200.1676
22192.168.200.168/29192.168.200.169 to 192.168.200.174192.168.200.1756
23192.168.200.176/29192.168.200.177 to 192.168.200.182192.168.200.1836
24192.168.200.184/29192.168.200.185 to 192.168.200.190192.168.200.1916
25192.168.200.192/29192.168.200.193 to 192.168.200.198192.168.200.1996
26192.168.200.200/29192.168.200.201 to 192.168.200.206192.168.200.2076
27192.168.200.208/29192.168.200.209 to 192.168.200.214192.168.200.2156
28192.168.200.216/29192.168.200.217 to 192.168.200.222192.168.200.2236
29192.168.200.224/29192.168.200.225 to 192.168.200.230192.168.200.2316
30192.168.200.232/29192.168.200.233 to 192.168.200.238192.168.200.2396
31192.168.200.240/29192.168.200.241 to 192.168.200.246192.168.200.2476
32192.168.200.248/29192.168.200.249 to 192.168.200.254192.168.200.2556
33192.168.201.0/29192.168.201.1 to 192.168.201.6192.168.201.76
34192.168.201.8/29192.168.201.9 to 192.168.201.14192.168.201.156
35192.168.201.16/29192.168.201.17 to 192.168.201.22192.168.201.236
36192.168.201.24/29192.168.201.25 to 192.168.201.30192.168.201.316
37192.168.201.32/29192.168.201.33 to 192.168.201.38192.168.201.396
38192.168.201.40/29192.168.201.41 to 192.168.201.46192.168.201.476
39192.168.201.48/29192.168.201.49 to 192.168.201.54192.168.201.556
40192.168.201.56/29192.168.201.57 to 192.168.201.62192.168.201.636
41192.168.201.64/29192.168.201.65 to 192.168.201.70192.168.201.716
42192.168.201.72/29192.168.201.73 to 192.168.201.78192.168.201.796
43192.168.201.80/29192.168.201.81 to 192.168.201.86192.168.201.876
44192.168.201.88/29192.168.201.89 to 192.168.201.94192.168.201.956
45192.168.201.96/29192.168.201.97 to 192.168.201.102192.168.201.1036
46192.168.201.104/29192.168.201.105 to 192.168.201.110192.168.201.1116
47192.168.201.112/29192.168.201.113 to 192.168.201.118192.168.201.1196
48192.168.201.120/29192.168.201.121 to 192.168.201.126192.168.201.1276
49192.168.201.128/29192.168.201.129 to 192.168.201.134192.168.201.1356
50192.168.201.136/29192.168.201.137 to 192.168.201.142192.168.201.1436
51192.168.201.144/29192.168.201.145 to 192.168.201.150192.168.201.1516
52192.168.201.152/29192.168.201.153 to 192.168.201.158192.168.201.1596
53192.168.201.160/29192.168.201.161 to 192.168.201.166192.168.201.1676
54192.168.201.168/29192.168.201.169 to 192.168.201.174192.168.201.1756
55192.168.201.176/29192.168.201.177 to 192.168.201.182192.168.201.1836
56192.168.201.184/29192.168.201.185 to 192.168.201.190192.168.201.1916
57192.168.201.192/29192.168.201.193 to 192.168.201.198192.168.201.1996
58192.168.201.200/29192.168.201.201 to 192.168.201.206192.168.201.2076
59192.168.201.208/29192.168.201.209 to 192.168.201.214192.168.201.2156
60192.168.201.216/29192.168.201.217 to 192.168.201.222192.168.201.2236
61192.168.201.224/29192.168.201.225 to 192.168.201.230192.168.201.2316
62192.168.201.232/29192.168.201.233 to 192.168.201.238192.168.201.2396
63192.168.201.240/29192.168.201.241 to 192.168.201.246192.168.201.2476
64192.168.201.248/29192.168.201.249 to 192.168.201.254192.168.201.2556
65192.168.202.0/29192.168.202.1 to 192.168.202.6192.168.202.76
66192.168.202.8/29192.168.202.9 to 192.168.202.14192.168.202.156
67192.168.202.16/29192.168.202.17 to 192.168.202.22192.168.202.236
68192.168.202.24/29192.168.202.25 to 192.168.202.30192.168.202.316
69192.168.202.32/29192.168.202.33 to 192.168.202.38192.168.202.396
70192.168.202.40/29192.168.202.41 to 192.168.202.46192.168.202.476
71192.168.202.48/29192.168.202.49 to 192.168.202.54192.168.202.556
72192.168.202.56/29192.168.202.57 to 192.168.202.62192.168.202.636
73192.168.202.64/29192.168.202.65 to 192.168.202.70192.168.202.716
74192.168.202.72/29192.168.202.73 to 192.168.202.78192.168.202.796
75192.168.202.80/29192.168.202.81 to 192.168.202.86192.168.202.876
76192.168.202.88/29192.168.202.89 to 192.168.202.94192.168.202.956
77192.168.202.96/29192.168.202.97 to 192.168.202.102192.168.202.1036
78192.168.202.104/29192.168.202.105 to 192.168.202.110192.168.202.1116
79192.168.202.112/29192.168.202.113 to 192.168.202.118192.168.202.1196
80192.168.202.120/29192.168.202.121 to 192.168.202.126192.168.202.1276
81192.168.202.128/29192.168.202.129 to 192.168.202.134192.168.202.1356
82192.168.202.136/29192.168.202.137 to 192.168.202.142192.168.202.1436
83192.168.202.144/29192.168.202.145 to 192.168.202.150192.168.202.1516
84192.168.202.152/29192.168.202.153 to 192.168.202.158192.168.202.1596
85192.168.202.160/29192.168.202.161 to 192.168.202.166192.168.202.1676
86192.168.202.168/29192.168.202.169 to 192.168.202.174192.168.202.1756
87192.168.202.176/29192.168.202.177 to 192.168.202.182192.168.202.1836
88192.168.202.184/29192.168.202.185 to 192.168.202.190192.168.202.1916
89192.168.202.192/29192.168.202.193 to 192.168.202.198192.168.202.1996
90192.168.202.200/29192.168.202.201 to 192.168.202.206192.168.202.2076
91192.168.202.208/29192.168.202.209 to 192.168.202.214192.168.202.2156
92192.168.202.216/29192.168.202.217 to 192.168.202.222192.168.202.2236
93192.168.202.224/29192.168.202.225 to 192.168.202.230192.168.202.2316
94192.168.202.232/29192.168.202.233 to 192.168.202.238192.168.202.2396
95192.168.202.240/29192.168.202.241 to 192.168.202.246192.168.202.2476
96192.168.202.248/29192.168.202.249 to 192.168.202.254192.168.202.2556
97192.168.203.0/29192.168.203.1 to 192.168.203.6192.168.203.76
98192.168.203.8/29192.168.203.9 to 192.168.203.14192.168.203.156
99192.168.203.16/29192.168.203.17 to 192.168.203.22192.168.203.236
100192.168.203.24/29192.168.203.25 to 192.168.203.30192.168.203.316
101192.168.203.32/29192.168.203.33 to 192.168.203.38192.168.203.396
102192.168.203.40/29192.168.203.41 to 192.168.203.46192.168.203.476
103192.168.203.48/29192.168.203.49 to 192.168.203.54192.168.203.556
104192.168.203.56/29192.168.203.57 to 192.168.203.62192.168.203.636
105192.168.203.64/29192.168.203.65 to 192.168.203.70192.168.203.716
106192.168.203.72/29192.168.203.73 to 192.168.203.78192.168.203.796
107192.168.203.80/29192.168.203.81 to 192.168.203.86192.168.203.876
108192.168.203.88/29192.168.203.89 to 192.168.203.94192.168.203.956
109192.168.203.96/29192.168.203.97 to 192.168.203.102192.168.203.1036
110192.168.203.104/29192.168.203.105 to 192.168.203.110192.168.203.1116
111192.168.203.112/29192.168.203.113 to 192.168.203.118192.168.203.1196
112192.168.203.120/29192.168.203.121 to 192.168.203.126192.168.203.1276
113192.168.203.128/29192.168.203.129 to 192.168.203.134192.168.203.1356
114192.168.203.136/29192.168.203.137 to 192.168.203.142192.168.203.1436
115192.168.203.144/29192.168.203.145 to 192.168.203.150192.168.203.1516
116192.168.203.152/29192.168.203.153 to 192.168.203.158192.168.203.1596
117192.168.203.160/29192.168.203.161 to 192.168.203.166192.168.203.1676
118192.168.203.168/29192.168.203.169 to 192.168.203.174192.168.203.1756
119192.168.203.176/29192.168.203.177 to 192.168.203.182192.168.203.1836
120192.168.203.184/29192.168.203.185 to 192.168.203.190192.168.203.1916
121192.168.203.192/29192.168.203.193 to 192.168.203.198192.168.203.1996
122192.168.203.200/29192.168.203.201 to 192.168.203.206192.168.203.2076
123192.168.203.208/29192.168.203.209 to 192.168.203.214192.168.203.2156
124192.168.203.216/29192.168.203.217 to 192.168.203.222192.168.203.2236
125192.168.203.224/29192.168.203.225 to 192.168.203.230192.168.203.2316
126192.168.203.232/29192.168.203.233 to 192.168.203.238192.168.203.2396
127192.168.203.240/29192.168.203.241 to 192.168.203.246192.168.203.2476
128192.168.203.248/29192.168.203.249 to 192.168.203.254192.168.203.2556
129192.168.204.0/29192.168.204.1 to 192.168.204.6192.168.204.76
130192.168.204.8/29192.168.204.9 to 192.168.204.14192.168.204.156
131192.168.204.16/29192.168.204.17 to 192.168.204.22192.168.204.236
132192.168.204.24/29192.168.204.25 to 192.168.204.30192.168.204.316
133192.168.204.32/29192.168.204.33 to 192.168.204.38192.168.204.396
134192.168.204.40/29192.168.204.41 to 192.168.204.46192.168.204.476
135192.168.204.48/29192.168.204.49 to 192.168.204.54192.168.204.556
136192.168.204.56/29192.168.204.57 to 192.168.204.62192.168.204.636
137192.168.204.64/29192.168.204.65 to 192.168.204.70192.168.204.716
138192.168.204.72/29192.168.204.73 to 192.168.204.78192.168.204.796
139192.168.204.80/29192.168.204.81 to 192.168.204.86192.168.204.876
140192.168.204.88/29192.168.204.89 to 192.168.204.94192.168.204.956
141192.168.204.96/29192.168.204.97 to 192.168.204.102192.168.204.1036
142192.168.204.104/29192.168.204.105 to 192.168.204.110192.168.204.1116
143192.168.204.112/29192.168.204.113 to 192.168.204.118192.168.204.1196
144192.168.204.120/29192.168.204.121 to 192.168.204.126192.168.204.1276
145192.168.204.128/29192.168.204.129 to 192.168.204.134192.168.204.1356
146192.168.204.136/29192.168.204.137 to 192.168.204.142192.168.204.1436
147192.168.204.144/29192.168.204.145 to 192.168.204.150192.168.204.1516
148192.168.204.152/29192.168.204.153 to 192.168.204.158192.168.204.1596
149192.168.204.160/29192.168.204.161 to 192.168.204.166192.168.204.1676
150192.168.204.168/29192.168.204.169 to 192.168.204.174192.168.204.1756
151192.168.204.176/29192.168.204.177 to 192.168.204.182192.168.204.1836
152192.168.204.184/29192.168.204.185 to 192.168.204.190192.168.204.1916
153192.168.204.192/29192.168.204.193 to 192.168.204.198192.168.204.1996
154192.168.204.200/29192.168.204.201 to 192.168.204.206192.168.204.2076
155192.168.204.208/29192.168.204.209 to 192.168.204.214192.168.204.2156
156192.168.204.216/29192.168.204.217 to 192.168.204.222192.168.204.2236
157192.168.204.224/29192.168.204.225 to 192.168.204.230192.168.204.2316
158192.168.204.232/29192.168.204.233 to 192.168.204.238192.168.204.2396
159192.168.204.240/29192.168.204.241 to 192.168.204.246192.168.204.2476
160192.168.204.248/29192.168.204.249 to 192.168.204.254192.168.204.2556
161192.168.205.0/29192.168.205.1 to 192.168.205.6192.168.205.76
162192.168.205.8/29192.168.205.9 to 192.168.205.14192.168.205.156
163192.168.205.16/29192.168.205.17 to 192.168.205.22192.168.205.236
164192.168.205.24/29192.168.205.25 to 192.168.205.30192.168.205.316
165192.168.205.32/29192.168.205.33 to 192.168.205.38192.168.205.396
166192.168.205.40/29192.168.205.41 to 192.168.205.46192.168.205.476
167192.168.205.48/29192.168.205.49 to 192.168.205.54192.168.205.556
168192.168.205.56/29192.168.205.57 to 192.168.205.62192.168.205.636
169192.168.205.64/29192.168.205.65 to 192.168.205.70192.168.205.716
170192.168.205.72/29192.168.205.73 to 192.168.205.78192.168.205.796
171192.168.205.80/29192.168.205.81 to 192.168.205.86192.168.205.876
172192.168.205.88/29192.168.205.89 to 192.168.205.94192.168.205.956
173192.168.205.96/29192.168.205.97 to 192.168.205.102192.168.205.1036
174192.168.205.104/29192.168.205.105 to 192.168.205.110192.168.205.1116
175192.168.205.112/29192.168.205.113 to 192.168.205.118192.168.205.1196
176192.168.205.120/29192.168.205.121 to 192.168.205.126192.168.205.1276
177192.168.205.128/29192.168.205.129 to 192.168.205.134192.168.205.1356
178192.168.205.136/29192.168.205.137 to 192.168.205.142192.168.205.1436
179192.168.205.144/29192.168.205.145 to 192.168.205.150192.168.205.1516
180192.168.205.152/29192.168.205.153 to 192.168.205.158192.168.205.1596
181192.168.205.160/29192.168.205.161 to 192.168.205.166192.168.205.1676
182192.168.205.168/29192.168.205.169 to 192.168.205.174192.168.205.1756
183192.168.205.176/29192.168.205.177 to 192.168.205.182192.168.205.1836
184192.168.205.184/29192.168.205.185 to 192.168.205.190192.168.205.1916
185192.168.205.192/29192.168.205.193 to 192.168.205.198192.168.205.1996
186192.168.205.200/29192.168.205.201 to 192.168.205.206192.168.205.2076
187192.168.205.208/29192.168.205.209 to 192.168.205.214192.168.205.2156
188192.168.205.216/29192.168.205.217 to 192.168.205.222192.168.205.2236
189192.168.205.224/29192.168.205.225 to 192.168.205.230192.168.205.2316
190192.168.205.232/29192.168.205.233 to 192.168.205.238192.168.205.2396
191192.168.205.240/29192.168.205.241 to 192.168.205.246192.168.205.2476
192192.168.205.248/29192.168.205.249 to 192.168.205.254192.168.205.2556
193192.168.206.0/29192.168.206.1 to 192.168.206.6192.168.206.76
194192.168.206.8/29192.168.206.9 to 192.168.206.14192.168.206.156
195192.168.206.16/29192.168.206.17 to 192.168.206.22192.168.206.236
196192.168.206.24/29192.168.206.25 to 192.168.206.30192.168.206.316
197192.168.206.32/29192.168.206.33 to 192.168.206.38192.168.206.396
198192.168.206.40/29192.168.206.41 to 192.168.206.46192.168.206.476
199192.168.206.48/29192.168.206.49 to 192.168.206.54192.168.206.556
200192.168.206.56/29192.168.206.57 to 192.168.206.62192.168.206.636
201192.168.206.64/29192.168.206.65 to 192.168.206.70192.168.206.716
202192.168.206.72/29192.168.206.73 to 192.168.206.78192.168.206.796
203192.168.206.80/29192.168.206.81 to 192.168.206.86192.168.206.876
204192.168.206.88/29192.168.206.89 to 192.168.206.94192.168.206.956
205192.168.206.96/29192.168.206.97 to 192.168.206.102192.168.206.1036
206192.168.206.104/29192.168.206.105 to 192.168.206.110192.168.206.1116
207192.168.206.112/29192.168.206.113 to 192.168.206.118192.168.206.1196
208192.168.206.120/29192.168.206.121 to 192.168.206.126192.168.206.1276
209192.168.206.128/29192.168.206.129 to 192.168.206.134192.168.206.1356
210192.168.206.136/29192.168.206.137 to 192.168.206.142192.168.206.1436
211192.168.206.144/29192.168.206.145 to 192.168.206.150192.168.206.1516
212192.168.206.152/29192.168.206.153 to 192.168.206.158192.168.206.1596
213192.168.206.160/29192.168.206.161 to 192.168.206.166192.168.206.1676
214192.168.206.168/29192.168.206.169 to 192.168.206.174192.168.206.1756
215192.168.206.176/29192.168.206.177 to 192.168.206.182192.168.206.1836
216192.168.206.184/29192.168.206.185 to 192.168.206.190192.168.206.1916
217192.168.206.192/29192.168.206.193 to 192.168.206.198192.168.206.1996
218192.168.206.200/29192.168.206.201 to 192.168.206.206192.168.206.2076
219192.168.206.208/29192.168.206.209 to 192.168.206.214192.168.206.2156
220192.168.206.216/29192.168.206.217 to 192.168.206.222192.168.206.2236
221192.168.206.224/29192.168.206.225 to 192.168.206.230192.168.206.2316
222192.168.206.232/29192.168.206.233 to 192.168.206.238192.168.206.2396
223192.168.206.240/29192.168.206.241 to 192.168.206.246192.168.206.2476
224192.168.206.248/29192.168.206.249 to 192.168.206.254192.168.206.2556
225192.168.207.0/29192.168.207.1 to 192.168.207.6192.168.207.76
226192.168.207.8/29192.168.207.9 to 192.168.207.14192.168.207.156
227192.168.207.16/29192.168.207.17 to 192.168.207.22192.168.207.236
228192.168.207.24/29192.168.207.25 to 192.168.207.30192.168.207.316
229192.168.207.32/29192.168.207.33 to 192.168.207.38192.168.207.396
230192.168.207.40/29192.168.207.41 to 192.168.207.46192.168.207.476
231192.168.207.48/29192.168.207.49 to 192.168.207.54192.168.207.556
232192.168.207.56/29192.168.207.57 to 192.168.207.62192.168.207.636
233192.168.207.64/29192.168.207.65 to 192.168.207.70192.168.207.716
234192.168.207.72/29192.168.207.73 to 192.168.207.78192.168.207.796
235192.168.207.80/29192.168.207.81 to 192.168.207.86192.168.207.876
236192.168.207.88/29192.168.207.89 to 192.168.207.94192.168.207.956
237192.168.207.96/29192.168.207.97 to 192.168.207.102192.168.207.1036
238192.168.207.104/29192.168.207.105 to 192.168.207.110192.168.207.1116
239192.168.207.112/29192.168.207.113 to 192.168.207.118192.168.207.1196
240192.168.207.120/29192.168.207.121 to 192.168.207.126192.168.207.1276
241192.168.207.128/29192.168.207.129 to 192.168.207.134192.168.207.1356
242192.168.207.136/29192.168.207.137 to 192.168.207.142192.168.207.1436
243192.168.207.144/29192.168.207.145 to 192.168.207.150192.168.207.1516
244192.168.207.152/29192.168.207.153 to 192.168.207.158192.168.207.1596
245192.168.207.160/29192.168.207.161 to 192.168.207.166192.168.207.1676
246192.168.207.168/29192.168.207.169 to 192.168.207.174192.168.207.1756
247192.168.207.176/29192.168.207.177 to 192.168.207.182192.168.207.1836
248192.168.207.184/29192.168.207.185 to 192.168.207.190192.168.207.1916
249192.168.207.192/29192.168.207.193 to 192.168.207.198192.168.207.1996
250192.168.207.200/29192.168.207.201 to 192.168.207.206192.168.207.2076
251192.168.207.208/29192.168.207.209 to 192.168.207.214192.168.207.2156
252192.168.207.216/29192.168.207.217 to 192.168.207.222192.168.207.2236
253192.168.207.224/29192.168.207.225 to 192.168.207.230192.168.207.2316
254192.168.207.232/29192.168.207.233 to 192.168.207.238192.168.207.2396
255192.168.207.240/29192.168.207.241 to 192.168.207.246192.168.207.2476
256192.168.207.248/29192.168.207.249 to 192.168.207.254192.168.207.2556

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.