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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.

Network207.2.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
207.2.0.0
Broadcast address
207.2.127.255
First usable
207.2.0.1
Last usable
207.2.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
C (default /24)
As numbers
Hex CF020000 · Integer 3473014784 to 3473047551
Reverse DNS zones
0.2.207.in-addr.arpa
1.2.207.in-addr.arpa
2.2.207.in-addr.arpa
3.2.207.in-addr.arpa
4.2.207.in-addr.arpa
5.2.207.in-addr.arpa
6.2.207.in-addr.arpa
7.2.207.in-addr.arpa
8.2.207.in-addr.arpa
9.2.207.in-addr.arpa
10.2.207.in-addr.arpa
11.2.207.in-addr.arpa
12.2.207.in-addr.arpa
13.2.207.in-addr.arpa
14.2.207.in-addr.arpa
15.2.207.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001111.00000010.00000000.00000000207.2.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network11001111.00000010.00000000.00000000207.2.0.0
Broadcast11001111.00000010.01111111.11111111207.2.127.255
Split into smaller subnets/29
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

207.2.0.0/17 makes 4,096 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1207.2.0.0/29207.2.0.1 to 207.2.0.6207.2.0.76
2207.2.0.8/29207.2.0.9 to 207.2.0.14207.2.0.156
3207.2.0.16/29207.2.0.17 to 207.2.0.22207.2.0.236
4207.2.0.24/29207.2.0.25 to 207.2.0.30207.2.0.316
5207.2.0.32/29207.2.0.33 to 207.2.0.38207.2.0.396
6207.2.0.40/29207.2.0.41 to 207.2.0.46207.2.0.476
7207.2.0.48/29207.2.0.49 to 207.2.0.54207.2.0.556
8207.2.0.56/29207.2.0.57 to 207.2.0.62207.2.0.636
9207.2.0.64/29207.2.0.65 to 207.2.0.70207.2.0.716
10207.2.0.72/29207.2.0.73 to 207.2.0.78207.2.0.796
11207.2.0.80/29207.2.0.81 to 207.2.0.86207.2.0.876
12207.2.0.88/29207.2.0.89 to 207.2.0.94207.2.0.956
13207.2.0.96/29207.2.0.97 to 207.2.0.102207.2.0.1036
14207.2.0.104/29207.2.0.105 to 207.2.0.110207.2.0.1116
15207.2.0.112/29207.2.0.113 to 207.2.0.118207.2.0.1196
16207.2.0.120/29207.2.0.121 to 207.2.0.126207.2.0.1276
17207.2.0.128/29207.2.0.129 to 207.2.0.134207.2.0.1356
18207.2.0.136/29207.2.0.137 to 207.2.0.142207.2.0.1436
19207.2.0.144/29207.2.0.145 to 207.2.0.150207.2.0.1516
20207.2.0.152/29207.2.0.153 to 207.2.0.158207.2.0.1596
21207.2.0.160/29207.2.0.161 to 207.2.0.166207.2.0.1676
22207.2.0.168/29207.2.0.169 to 207.2.0.174207.2.0.1756
23207.2.0.176/29207.2.0.177 to 207.2.0.182207.2.0.1836
24207.2.0.184/29207.2.0.185 to 207.2.0.190207.2.0.1916
25207.2.0.192/29207.2.0.193 to 207.2.0.198207.2.0.1996
26207.2.0.200/29207.2.0.201 to 207.2.0.206207.2.0.2076
27207.2.0.208/29207.2.0.209 to 207.2.0.214207.2.0.2156
28207.2.0.216/29207.2.0.217 to 207.2.0.222207.2.0.2236
29207.2.0.224/29207.2.0.225 to 207.2.0.230207.2.0.2316
30207.2.0.232/29207.2.0.233 to 207.2.0.238207.2.0.2396
31207.2.0.240/29207.2.0.241 to 207.2.0.246207.2.0.2476
32207.2.0.248/29207.2.0.249 to 207.2.0.254207.2.0.2556
33207.2.1.0/29207.2.1.1 to 207.2.1.6207.2.1.76
34207.2.1.8/29207.2.1.9 to 207.2.1.14207.2.1.156
35207.2.1.16/29207.2.1.17 to 207.2.1.22207.2.1.236
36207.2.1.24/29207.2.1.25 to 207.2.1.30207.2.1.316
37207.2.1.32/29207.2.1.33 to 207.2.1.38207.2.1.396
38207.2.1.40/29207.2.1.41 to 207.2.1.46207.2.1.476
39207.2.1.48/29207.2.1.49 to 207.2.1.54207.2.1.556
40207.2.1.56/29207.2.1.57 to 207.2.1.62207.2.1.636
41207.2.1.64/29207.2.1.65 to 207.2.1.70207.2.1.716
42207.2.1.72/29207.2.1.73 to 207.2.1.78207.2.1.796
43207.2.1.80/29207.2.1.81 to 207.2.1.86207.2.1.876
44207.2.1.88/29207.2.1.89 to 207.2.1.94207.2.1.956
45207.2.1.96/29207.2.1.97 to 207.2.1.102207.2.1.1036
46207.2.1.104/29207.2.1.105 to 207.2.1.110207.2.1.1116
47207.2.1.112/29207.2.1.113 to 207.2.1.118207.2.1.1196
48207.2.1.120/29207.2.1.121 to 207.2.1.126207.2.1.1276
49207.2.1.128/29207.2.1.129 to 207.2.1.134207.2.1.1356
50207.2.1.136/29207.2.1.137 to 207.2.1.142207.2.1.1436
51207.2.1.144/29207.2.1.145 to 207.2.1.150207.2.1.1516
52207.2.1.152/29207.2.1.153 to 207.2.1.158207.2.1.1596
53207.2.1.160/29207.2.1.161 to 207.2.1.166207.2.1.1676
54207.2.1.168/29207.2.1.169 to 207.2.1.174207.2.1.1756
55207.2.1.176/29207.2.1.177 to 207.2.1.182207.2.1.1836
56207.2.1.184/29207.2.1.185 to 207.2.1.190207.2.1.1916
57207.2.1.192/29207.2.1.193 to 207.2.1.198207.2.1.1996
58207.2.1.200/29207.2.1.201 to 207.2.1.206207.2.1.2076
59207.2.1.208/29207.2.1.209 to 207.2.1.214207.2.1.2156
60207.2.1.216/29207.2.1.217 to 207.2.1.222207.2.1.2236
61207.2.1.224/29207.2.1.225 to 207.2.1.230207.2.1.2316
62207.2.1.232/29207.2.1.233 to 207.2.1.238207.2.1.2396
63207.2.1.240/29207.2.1.241 to 207.2.1.246207.2.1.2476
64207.2.1.248/29207.2.1.249 to 207.2.1.254207.2.1.2556
65207.2.2.0/29207.2.2.1 to 207.2.2.6207.2.2.76
66207.2.2.8/29207.2.2.9 to 207.2.2.14207.2.2.156
67207.2.2.16/29207.2.2.17 to 207.2.2.22207.2.2.236
68207.2.2.24/29207.2.2.25 to 207.2.2.30207.2.2.316
69207.2.2.32/29207.2.2.33 to 207.2.2.38207.2.2.396
70207.2.2.40/29207.2.2.41 to 207.2.2.46207.2.2.476
71207.2.2.48/29207.2.2.49 to 207.2.2.54207.2.2.556
72207.2.2.56/29207.2.2.57 to 207.2.2.62207.2.2.636
73207.2.2.64/29207.2.2.65 to 207.2.2.70207.2.2.716
74207.2.2.72/29207.2.2.73 to 207.2.2.78207.2.2.796
75207.2.2.80/29207.2.2.81 to 207.2.2.86207.2.2.876
76207.2.2.88/29207.2.2.89 to 207.2.2.94207.2.2.956
77207.2.2.96/29207.2.2.97 to 207.2.2.102207.2.2.1036
78207.2.2.104/29207.2.2.105 to 207.2.2.110207.2.2.1116
79207.2.2.112/29207.2.2.113 to 207.2.2.118207.2.2.1196
80207.2.2.120/29207.2.2.121 to 207.2.2.126207.2.2.1276
81207.2.2.128/29207.2.2.129 to 207.2.2.134207.2.2.1356
82207.2.2.136/29207.2.2.137 to 207.2.2.142207.2.2.1436
83207.2.2.144/29207.2.2.145 to 207.2.2.150207.2.2.1516
84207.2.2.152/29207.2.2.153 to 207.2.2.158207.2.2.1596
85207.2.2.160/29207.2.2.161 to 207.2.2.166207.2.2.1676
86207.2.2.168/29207.2.2.169 to 207.2.2.174207.2.2.1756
87207.2.2.176/29207.2.2.177 to 207.2.2.182207.2.2.1836
88207.2.2.184/29207.2.2.185 to 207.2.2.190207.2.2.1916
89207.2.2.192/29207.2.2.193 to 207.2.2.198207.2.2.1996
90207.2.2.200/29207.2.2.201 to 207.2.2.206207.2.2.2076
91207.2.2.208/29207.2.2.209 to 207.2.2.214207.2.2.2156
92207.2.2.216/29207.2.2.217 to 207.2.2.222207.2.2.2236
93207.2.2.224/29207.2.2.225 to 207.2.2.230207.2.2.2316
94207.2.2.232/29207.2.2.233 to 207.2.2.238207.2.2.2396
95207.2.2.240/29207.2.2.241 to 207.2.2.246207.2.2.2476
96207.2.2.248/29207.2.2.249 to 207.2.2.254207.2.2.2556
97207.2.3.0/29207.2.3.1 to 207.2.3.6207.2.3.76
98207.2.3.8/29207.2.3.9 to 207.2.3.14207.2.3.156
99207.2.3.16/29207.2.3.17 to 207.2.3.22207.2.3.236
100207.2.3.24/29207.2.3.25 to 207.2.3.30207.2.3.316
101207.2.3.32/29207.2.3.33 to 207.2.3.38207.2.3.396
102207.2.3.40/29207.2.3.41 to 207.2.3.46207.2.3.476
103207.2.3.48/29207.2.3.49 to 207.2.3.54207.2.3.556
104207.2.3.56/29207.2.3.57 to 207.2.3.62207.2.3.636
105207.2.3.64/29207.2.3.65 to 207.2.3.70207.2.3.716
106207.2.3.72/29207.2.3.73 to 207.2.3.78207.2.3.796
107207.2.3.80/29207.2.3.81 to 207.2.3.86207.2.3.876
108207.2.3.88/29207.2.3.89 to 207.2.3.94207.2.3.956
109207.2.3.96/29207.2.3.97 to 207.2.3.102207.2.3.1036
110207.2.3.104/29207.2.3.105 to 207.2.3.110207.2.3.1116
111207.2.3.112/29207.2.3.113 to 207.2.3.118207.2.3.1196
112207.2.3.120/29207.2.3.121 to 207.2.3.126207.2.3.1276
113207.2.3.128/29207.2.3.129 to 207.2.3.134207.2.3.1356
114207.2.3.136/29207.2.3.137 to 207.2.3.142207.2.3.1436
115207.2.3.144/29207.2.3.145 to 207.2.3.150207.2.3.1516
116207.2.3.152/29207.2.3.153 to 207.2.3.158207.2.3.1596
117207.2.3.160/29207.2.3.161 to 207.2.3.166207.2.3.1676
118207.2.3.168/29207.2.3.169 to 207.2.3.174207.2.3.1756
119207.2.3.176/29207.2.3.177 to 207.2.3.182207.2.3.1836
120207.2.3.184/29207.2.3.185 to 207.2.3.190207.2.3.1916
121207.2.3.192/29207.2.3.193 to 207.2.3.198207.2.3.1996
122207.2.3.200/29207.2.3.201 to 207.2.3.206207.2.3.2076
123207.2.3.208/29207.2.3.209 to 207.2.3.214207.2.3.2156
124207.2.3.216/29207.2.3.217 to 207.2.3.222207.2.3.2236
125207.2.3.224/29207.2.3.225 to 207.2.3.230207.2.3.2316
126207.2.3.232/29207.2.3.233 to 207.2.3.238207.2.3.2396
127207.2.3.240/29207.2.3.241 to 207.2.3.246207.2.3.2476
128207.2.3.248/29207.2.3.249 to 207.2.3.254207.2.3.2556
129207.2.4.0/29207.2.4.1 to 207.2.4.6207.2.4.76
130207.2.4.8/29207.2.4.9 to 207.2.4.14207.2.4.156
131207.2.4.16/29207.2.4.17 to 207.2.4.22207.2.4.236
132207.2.4.24/29207.2.4.25 to 207.2.4.30207.2.4.316
133207.2.4.32/29207.2.4.33 to 207.2.4.38207.2.4.396
134207.2.4.40/29207.2.4.41 to 207.2.4.46207.2.4.476
135207.2.4.48/29207.2.4.49 to 207.2.4.54207.2.4.556
136207.2.4.56/29207.2.4.57 to 207.2.4.62207.2.4.636
137207.2.4.64/29207.2.4.65 to 207.2.4.70207.2.4.716
138207.2.4.72/29207.2.4.73 to 207.2.4.78207.2.4.796
139207.2.4.80/29207.2.4.81 to 207.2.4.86207.2.4.876
140207.2.4.88/29207.2.4.89 to 207.2.4.94207.2.4.956
141207.2.4.96/29207.2.4.97 to 207.2.4.102207.2.4.1036
142207.2.4.104/29207.2.4.105 to 207.2.4.110207.2.4.1116
143207.2.4.112/29207.2.4.113 to 207.2.4.118207.2.4.1196
144207.2.4.120/29207.2.4.121 to 207.2.4.126207.2.4.1276
145207.2.4.128/29207.2.4.129 to 207.2.4.134207.2.4.1356
146207.2.4.136/29207.2.4.137 to 207.2.4.142207.2.4.1436
147207.2.4.144/29207.2.4.145 to 207.2.4.150207.2.4.1516
148207.2.4.152/29207.2.4.153 to 207.2.4.158207.2.4.1596
149207.2.4.160/29207.2.4.161 to 207.2.4.166207.2.4.1676
150207.2.4.168/29207.2.4.169 to 207.2.4.174207.2.4.1756
151207.2.4.176/29207.2.4.177 to 207.2.4.182207.2.4.1836
152207.2.4.184/29207.2.4.185 to 207.2.4.190207.2.4.1916
153207.2.4.192/29207.2.4.193 to 207.2.4.198207.2.4.1996
154207.2.4.200/29207.2.4.201 to 207.2.4.206207.2.4.2076
155207.2.4.208/29207.2.4.209 to 207.2.4.214207.2.4.2156
156207.2.4.216/29207.2.4.217 to 207.2.4.222207.2.4.2236
157207.2.4.224/29207.2.4.225 to 207.2.4.230207.2.4.2316
158207.2.4.232/29207.2.4.233 to 207.2.4.238207.2.4.2396
159207.2.4.240/29207.2.4.241 to 207.2.4.246207.2.4.2476
160207.2.4.248/29207.2.4.249 to 207.2.4.254207.2.4.2556
161207.2.5.0/29207.2.5.1 to 207.2.5.6207.2.5.76
162207.2.5.8/29207.2.5.9 to 207.2.5.14207.2.5.156
163207.2.5.16/29207.2.5.17 to 207.2.5.22207.2.5.236
164207.2.5.24/29207.2.5.25 to 207.2.5.30207.2.5.316
165207.2.5.32/29207.2.5.33 to 207.2.5.38207.2.5.396
166207.2.5.40/29207.2.5.41 to 207.2.5.46207.2.5.476
167207.2.5.48/29207.2.5.49 to 207.2.5.54207.2.5.556
168207.2.5.56/29207.2.5.57 to 207.2.5.62207.2.5.636
169207.2.5.64/29207.2.5.65 to 207.2.5.70207.2.5.716
170207.2.5.72/29207.2.5.73 to 207.2.5.78207.2.5.796
171207.2.5.80/29207.2.5.81 to 207.2.5.86207.2.5.876
172207.2.5.88/29207.2.5.89 to 207.2.5.94207.2.5.956
173207.2.5.96/29207.2.5.97 to 207.2.5.102207.2.5.1036
174207.2.5.104/29207.2.5.105 to 207.2.5.110207.2.5.1116
175207.2.5.112/29207.2.5.113 to 207.2.5.118207.2.5.1196
176207.2.5.120/29207.2.5.121 to 207.2.5.126207.2.5.1276
177207.2.5.128/29207.2.5.129 to 207.2.5.134207.2.5.1356
178207.2.5.136/29207.2.5.137 to 207.2.5.142207.2.5.1436
179207.2.5.144/29207.2.5.145 to 207.2.5.150207.2.5.1516
180207.2.5.152/29207.2.5.153 to 207.2.5.158207.2.5.1596
181207.2.5.160/29207.2.5.161 to 207.2.5.166207.2.5.1676
182207.2.5.168/29207.2.5.169 to 207.2.5.174207.2.5.1756
183207.2.5.176/29207.2.5.177 to 207.2.5.182207.2.5.1836
184207.2.5.184/29207.2.5.185 to 207.2.5.190207.2.5.1916
185207.2.5.192/29207.2.5.193 to 207.2.5.198207.2.5.1996
186207.2.5.200/29207.2.5.201 to 207.2.5.206207.2.5.2076
187207.2.5.208/29207.2.5.209 to 207.2.5.214207.2.5.2156
188207.2.5.216/29207.2.5.217 to 207.2.5.222207.2.5.2236
189207.2.5.224/29207.2.5.225 to 207.2.5.230207.2.5.2316
190207.2.5.232/29207.2.5.233 to 207.2.5.238207.2.5.2396
191207.2.5.240/29207.2.5.241 to 207.2.5.246207.2.5.2476
192207.2.5.248/29207.2.5.249 to 207.2.5.254207.2.5.2556
193207.2.6.0/29207.2.6.1 to 207.2.6.6207.2.6.76
194207.2.6.8/29207.2.6.9 to 207.2.6.14207.2.6.156
195207.2.6.16/29207.2.6.17 to 207.2.6.22207.2.6.236
196207.2.6.24/29207.2.6.25 to 207.2.6.30207.2.6.316
197207.2.6.32/29207.2.6.33 to 207.2.6.38207.2.6.396
198207.2.6.40/29207.2.6.41 to 207.2.6.46207.2.6.476
199207.2.6.48/29207.2.6.49 to 207.2.6.54207.2.6.556
200207.2.6.56/29207.2.6.57 to 207.2.6.62207.2.6.636
201207.2.6.64/29207.2.6.65 to 207.2.6.70207.2.6.716
202207.2.6.72/29207.2.6.73 to 207.2.6.78207.2.6.796
203207.2.6.80/29207.2.6.81 to 207.2.6.86207.2.6.876
204207.2.6.88/29207.2.6.89 to 207.2.6.94207.2.6.956
205207.2.6.96/29207.2.6.97 to 207.2.6.102207.2.6.1036
206207.2.6.104/29207.2.6.105 to 207.2.6.110207.2.6.1116
207207.2.6.112/29207.2.6.113 to 207.2.6.118207.2.6.1196
208207.2.6.120/29207.2.6.121 to 207.2.6.126207.2.6.1276
209207.2.6.128/29207.2.6.129 to 207.2.6.134207.2.6.1356
210207.2.6.136/29207.2.6.137 to 207.2.6.142207.2.6.1436
211207.2.6.144/29207.2.6.145 to 207.2.6.150207.2.6.1516
212207.2.6.152/29207.2.6.153 to 207.2.6.158207.2.6.1596
213207.2.6.160/29207.2.6.161 to 207.2.6.166207.2.6.1676
214207.2.6.168/29207.2.6.169 to 207.2.6.174207.2.6.1756
215207.2.6.176/29207.2.6.177 to 207.2.6.182207.2.6.1836
216207.2.6.184/29207.2.6.185 to 207.2.6.190207.2.6.1916
217207.2.6.192/29207.2.6.193 to 207.2.6.198207.2.6.1996
218207.2.6.200/29207.2.6.201 to 207.2.6.206207.2.6.2076
219207.2.6.208/29207.2.6.209 to 207.2.6.214207.2.6.2156
220207.2.6.216/29207.2.6.217 to 207.2.6.222207.2.6.2236
221207.2.6.224/29207.2.6.225 to 207.2.6.230207.2.6.2316
222207.2.6.232/29207.2.6.233 to 207.2.6.238207.2.6.2396
223207.2.6.240/29207.2.6.241 to 207.2.6.246207.2.6.2476
224207.2.6.248/29207.2.6.249 to 207.2.6.254207.2.6.2556
225207.2.7.0/29207.2.7.1 to 207.2.7.6207.2.7.76
226207.2.7.8/29207.2.7.9 to 207.2.7.14207.2.7.156
227207.2.7.16/29207.2.7.17 to 207.2.7.22207.2.7.236
228207.2.7.24/29207.2.7.25 to 207.2.7.30207.2.7.316
229207.2.7.32/29207.2.7.33 to 207.2.7.38207.2.7.396
230207.2.7.40/29207.2.7.41 to 207.2.7.46207.2.7.476
231207.2.7.48/29207.2.7.49 to 207.2.7.54207.2.7.556
232207.2.7.56/29207.2.7.57 to 207.2.7.62207.2.7.636
233207.2.7.64/29207.2.7.65 to 207.2.7.70207.2.7.716
234207.2.7.72/29207.2.7.73 to 207.2.7.78207.2.7.796
235207.2.7.80/29207.2.7.81 to 207.2.7.86207.2.7.876
236207.2.7.88/29207.2.7.89 to 207.2.7.94207.2.7.956
237207.2.7.96/29207.2.7.97 to 207.2.7.102207.2.7.1036
238207.2.7.104/29207.2.7.105 to 207.2.7.110207.2.7.1116
239207.2.7.112/29207.2.7.113 to 207.2.7.118207.2.7.1196
240207.2.7.120/29207.2.7.121 to 207.2.7.126207.2.7.1276
241207.2.7.128/29207.2.7.129 to 207.2.7.134207.2.7.1356
242207.2.7.136/29207.2.7.137 to 207.2.7.142207.2.7.1436
243207.2.7.144/29207.2.7.145 to 207.2.7.150207.2.7.1516
244207.2.7.152/29207.2.7.153 to 207.2.7.158207.2.7.1596
245207.2.7.160/29207.2.7.161 to 207.2.7.166207.2.7.1676
246207.2.7.168/29207.2.7.169 to 207.2.7.174207.2.7.1756
247207.2.7.176/29207.2.7.177 to 207.2.7.182207.2.7.1836
248207.2.7.184/29207.2.7.185 to 207.2.7.190207.2.7.1916
249207.2.7.192/29207.2.7.193 to 207.2.7.198207.2.7.1996
250207.2.7.200/29207.2.7.201 to 207.2.7.206207.2.7.2076
251207.2.7.208/29207.2.7.209 to 207.2.7.214207.2.7.2156
252207.2.7.216/29207.2.7.217 to 207.2.7.222207.2.7.2236
253207.2.7.224/29207.2.7.225 to 207.2.7.230207.2.7.2316
254207.2.7.232/29207.2.7.233 to 207.2.7.238207.2.7.2396
255207.2.7.240/29207.2.7.241 to 207.2.7.246207.2.7.2476
256207.2.7.248/29207.2.7.249 to 207.2.7.254207.2.7.2556

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.