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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.

Network170.3.0.0/20
Usable hosts4,094
Subnet mask255.255.240.0
Addresses4,096
Network address
170.3.0.0
Broadcast address
170.3.15.255
First usable
170.3.0.1
Last usable
170.3.15.254
Usable hosts
4,094 (4,096 less the network and broadcast addresses)
Subnet mask
255.255.240.0
Wildcard mask
0.0.15.255 (Cisco ACLs, OSPF)
Prefix length
/20
Type
Public public
Old class
B (default /16)
As numbers
Hex AA030000 · Integer 2852323328 to 2852327423
Reverse DNS zones
0.3.170.in-addr.arpa
1.3.170.in-addr.arpa
2.3.170.in-addr.arpa
3.3.170.in-addr.arpa
4.3.170.in-addr.arpa
5.3.170.in-addr.arpa
6.3.170.in-addr.arpa
7.3.170.in-addr.arpa
8.3.170.in-addr.arpa
9.3.170.in-addr.arpa
10.3.170.in-addr.arpa
11.3.170.in-addr.arpa
12.3.170.in-addr.arpa
13.3.170.in-addr.arpa
14.3.170.in-addr.arpa
15.3.170.in-addr.arpa
/20 is not on a 8-bit boundary, so it takes 16 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10101010.00000011.00000000.00000000170.3.0.0
Subnet mask11111111.11111111.11110000.00000000255.255.240.0
Network10101010.00000011.00000000.00000000170.3.0.0
Broadcast10101010.00000011.00001111.11111111170.3.15.255
Split into smaller subnets/28
/21 (2)/22 (4)/23 (8)/24 (16)/25 (32)/26 (64)/27 (128)/28 (256)/29 (512)/30 (1,024)/31 (2,048)/32 (4,096)

170.3.0.0/20 makes 256 subnets of /28.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1170.3.0.0/28170.3.0.1 to 170.3.0.14170.3.0.1514
2170.3.0.16/28170.3.0.17 to 170.3.0.30170.3.0.3114
3170.3.0.32/28170.3.0.33 to 170.3.0.46170.3.0.4714
4170.3.0.48/28170.3.0.49 to 170.3.0.62170.3.0.6314
5170.3.0.64/28170.3.0.65 to 170.3.0.78170.3.0.7914
6170.3.0.80/28170.3.0.81 to 170.3.0.94170.3.0.9514
7170.3.0.96/28170.3.0.97 to 170.3.0.110170.3.0.11114
8170.3.0.112/28170.3.0.113 to 170.3.0.126170.3.0.12714
9170.3.0.128/28170.3.0.129 to 170.3.0.142170.3.0.14314
10170.3.0.144/28170.3.0.145 to 170.3.0.158170.3.0.15914
11170.3.0.160/28170.3.0.161 to 170.3.0.174170.3.0.17514
12170.3.0.176/28170.3.0.177 to 170.3.0.190170.3.0.19114
13170.3.0.192/28170.3.0.193 to 170.3.0.206170.3.0.20714
14170.3.0.208/28170.3.0.209 to 170.3.0.222170.3.0.22314
15170.3.0.224/28170.3.0.225 to 170.3.0.238170.3.0.23914
16170.3.0.240/28170.3.0.241 to 170.3.0.254170.3.0.25514
17170.3.1.0/28170.3.1.1 to 170.3.1.14170.3.1.1514
18170.3.1.16/28170.3.1.17 to 170.3.1.30170.3.1.3114
19170.3.1.32/28170.3.1.33 to 170.3.1.46170.3.1.4714
20170.3.1.48/28170.3.1.49 to 170.3.1.62170.3.1.6314
21170.3.1.64/28170.3.1.65 to 170.3.1.78170.3.1.7914
22170.3.1.80/28170.3.1.81 to 170.3.1.94170.3.1.9514
23170.3.1.96/28170.3.1.97 to 170.3.1.110170.3.1.11114
24170.3.1.112/28170.3.1.113 to 170.3.1.126170.3.1.12714
25170.3.1.128/28170.3.1.129 to 170.3.1.142170.3.1.14314
26170.3.1.144/28170.3.1.145 to 170.3.1.158170.3.1.15914
27170.3.1.160/28170.3.1.161 to 170.3.1.174170.3.1.17514
28170.3.1.176/28170.3.1.177 to 170.3.1.190170.3.1.19114
29170.3.1.192/28170.3.1.193 to 170.3.1.206170.3.1.20714
30170.3.1.208/28170.3.1.209 to 170.3.1.222170.3.1.22314
31170.3.1.224/28170.3.1.225 to 170.3.1.238170.3.1.23914
32170.3.1.240/28170.3.1.241 to 170.3.1.254170.3.1.25514
33170.3.2.0/28170.3.2.1 to 170.3.2.14170.3.2.1514
34170.3.2.16/28170.3.2.17 to 170.3.2.30170.3.2.3114
35170.3.2.32/28170.3.2.33 to 170.3.2.46170.3.2.4714
36170.3.2.48/28170.3.2.49 to 170.3.2.62170.3.2.6314
37170.3.2.64/28170.3.2.65 to 170.3.2.78170.3.2.7914
38170.3.2.80/28170.3.2.81 to 170.3.2.94170.3.2.9514
39170.3.2.96/28170.3.2.97 to 170.3.2.110170.3.2.11114
40170.3.2.112/28170.3.2.113 to 170.3.2.126170.3.2.12714
41170.3.2.128/28170.3.2.129 to 170.3.2.142170.3.2.14314
42170.3.2.144/28170.3.2.145 to 170.3.2.158170.3.2.15914
43170.3.2.160/28170.3.2.161 to 170.3.2.174170.3.2.17514
44170.3.2.176/28170.3.2.177 to 170.3.2.190170.3.2.19114
45170.3.2.192/28170.3.2.193 to 170.3.2.206170.3.2.20714
46170.3.2.208/28170.3.2.209 to 170.3.2.222170.3.2.22314
47170.3.2.224/28170.3.2.225 to 170.3.2.238170.3.2.23914
48170.3.2.240/28170.3.2.241 to 170.3.2.254170.3.2.25514
49170.3.3.0/28170.3.3.1 to 170.3.3.14170.3.3.1514
50170.3.3.16/28170.3.3.17 to 170.3.3.30170.3.3.3114
51170.3.3.32/28170.3.3.33 to 170.3.3.46170.3.3.4714
52170.3.3.48/28170.3.3.49 to 170.3.3.62170.3.3.6314
53170.3.3.64/28170.3.3.65 to 170.3.3.78170.3.3.7914
54170.3.3.80/28170.3.3.81 to 170.3.3.94170.3.3.9514
55170.3.3.96/28170.3.3.97 to 170.3.3.110170.3.3.11114
56170.3.3.112/28170.3.3.113 to 170.3.3.126170.3.3.12714
57170.3.3.128/28170.3.3.129 to 170.3.3.142170.3.3.14314
58170.3.3.144/28170.3.3.145 to 170.3.3.158170.3.3.15914
59170.3.3.160/28170.3.3.161 to 170.3.3.174170.3.3.17514
60170.3.3.176/28170.3.3.177 to 170.3.3.190170.3.3.19114
61170.3.3.192/28170.3.3.193 to 170.3.3.206170.3.3.20714
62170.3.3.208/28170.3.3.209 to 170.3.3.222170.3.3.22314
63170.3.3.224/28170.3.3.225 to 170.3.3.238170.3.3.23914
64170.3.3.240/28170.3.3.241 to 170.3.3.254170.3.3.25514
65170.3.4.0/28170.3.4.1 to 170.3.4.14170.3.4.1514
66170.3.4.16/28170.3.4.17 to 170.3.4.30170.3.4.3114
67170.3.4.32/28170.3.4.33 to 170.3.4.46170.3.4.4714
68170.3.4.48/28170.3.4.49 to 170.3.4.62170.3.4.6314
69170.3.4.64/28170.3.4.65 to 170.3.4.78170.3.4.7914
70170.3.4.80/28170.3.4.81 to 170.3.4.94170.3.4.9514
71170.3.4.96/28170.3.4.97 to 170.3.4.110170.3.4.11114
72170.3.4.112/28170.3.4.113 to 170.3.4.126170.3.4.12714
73170.3.4.128/28170.3.4.129 to 170.3.4.142170.3.4.14314
74170.3.4.144/28170.3.4.145 to 170.3.4.158170.3.4.15914
75170.3.4.160/28170.3.4.161 to 170.3.4.174170.3.4.17514
76170.3.4.176/28170.3.4.177 to 170.3.4.190170.3.4.19114
77170.3.4.192/28170.3.4.193 to 170.3.4.206170.3.4.20714
78170.3.4.208/28170.3.4.209 to 170.3.4.222170.3.4.22314
79170.3.4.224/28170.3.4.225 to 170.3.4.238170.3.4.23914
80170.3.4.240/28170.3.4.241 to 170.3.4.254170.3.4.25514
81170.3.5.0/28170.3.5.1 to 170.3.5.14170.3.5.1514
82170.3.5.16/28170.3.5.17 to 170.3.5.30170.3.5.3114
83170.3.5.32/28170.3.5.33 to 170.3.5.46170.3.5.4714
84170.3.5.48/28170.3.5.49 to 170.3.5.62170.3.5.6314
85170.3.5.64/28170.3.5.65 to 170.3.5.78170.3.5.7914
86170.3.5.80/28170.3.5.81 to 170.3.5.94170.3.5.9514
87170.3.5.96/28170.3.5.97 to 170.3.5.110170.3.5.11114
88170.3.5.112/28170.3.5.113 to 170.3.5.126170.3.5.12714
89170.3.5.128/28170.3.5.129 to 170.3.5.142170.3.5.14314
90170.3.5.144/28170.3.5.145 to 170.3.5.158170.3.5.15914
91170.3.5.160/28170.3.5.161 to 170.3.5.174170.3.5.17514
92170.3.5.176/28170.3.5.177 to 170.3.5.190170.3.5.19114
93170.3.5.192/28170.3.5.193 to 170.3.5.206170.3.5.20714
94170.3.5.208/28170.3.5.209 to 170.3.5.222170.3.5.22314
95170.3.5.224/28170.3.5.225 to 170.3.5.238170.3.5.23914
96170.3.5.240/28170.3.5.241 to 170.3.5.254170.3.5.25514
97170.3.6.0/28170.3.6.1 to 170.3.6.14170.3.6.1514
98170.3.6.16/28170.3.6.17 to 170.3.6.30170.3.6.3114
99170.3.6.32/28170.3.6.33 to 170.3.6.46170.3.6.4714
100170.3.6.48/28170.3.6.49 to 170.3.6.62170.3.6.6314
101170.3.6.64/28170.3.6.65 to 170.3.6.78170.3.6.7914
102170.3.6.80/28170.3.6.81 to 170.3.6.94170.3.6.9514
103170.3.6.96/28170.3.6.97 to 170.3.6.110170.3.6.11114
104170.3.6.112/28170.3.6.113 to 170.3.6.126170.3.6.12714
105170.3.6.128/28170.3.6.129 to 170.3.6.142170.3.6.14314
106170.3.6.144/28170.3.6.145 to 170.3.6.158170.3.6.15914
107170.3.6.160/28170.3.6.161 to 170.3.6.174170.3.6.17514
108170.3.6.176/28170.3.6.177 to 170.3.6.190170.3.6.19114
109170.3.6.192/28170.3.6.193 to 170.3.6.206170.3.6.20714
110170.3.6.208/28170.3.6.209 to 170.3.6.222170.3.6.22314
111170.3.6.224/28170.3.6.225 to 170.3.6.238170.3.6.23914
112170.3.6.240/28170.3.6.241 to 170.3.6.254170.3.6.25514
113170.3.7.0/28170.3.7.1 to 170.3.7.14170.3.7.1514
114170.3.7.16/28170.3.7.17 to 170.3.7.30170.3.7.3114
115170.3.7.32/28170.3.7.33 to 170.3.7.46170.3.7.4714
116170.3.7.48/28170.3.7.49 to 170.3.7.62170.3.7.6314
117170.3.7.64/28170.3.7.65 to 170.3.7.78170.3.7.7914
118170.3.7.80/28170.3.7.81 to 170.3.7.94170.3.7.9514
119170.3.7.96/28170.3.7.97 to 170.3.7.110170.3.7.11114
120170.3.7.112/28170.3.7.113 to 170.3.7.126170.3.7.12714
121170.3.7.128/28170.3.7.129 to 170.3.7.142170.3.7.14314
122170.3.7.144/28170.3.7.145 to 170.3.7.158170.3.7.15914
123170.3.7.160/28170.3.7.161 to 170.3.7.174170.3.7.17514
124170.3.7.176/28170.3.7.177 to 170.3.7.190170.3.7.19114
125170.3.7.192/28170.3.7.193 to 170.3.7.206170.3.7.20714
126170.3.7.208/28170.3.7.209 to 170.3.7.222170.3.7.22314
127170.3.7.224/28170.3.7.225 to 170.3.7.238170.3.7.23914
128170.3.7.240/28170.3.7.241 to 170.3.7.254170.3.7.25514
129170.3.8.0/28170.3.8.1 to 170.3.8.14170.3.8.1514
130170.3.8.16/28170.3.8.17 to 170.3.8.30170.3.8.3114
131170.3.8.32/28170.3.8.33 to 170.3.8.46170.3.8.4714
132170.3.8.48/28170.3.8.49 to 170.3.8.62170.3.8.6314
133170.3.8.64/28170.3.8.65 to 170.3.8.78170.3.8.7914
134170.3.8.80/28170.3.8.81 to 170.3.8.94170.3.8.9514
135170.3.8.96/28170.3.8.97 to 170.3.8.110170.3.8.11114
136170.3.8.112/28170.3.8.113 to 170.3.8.126170.3.8.12714
137170.3.8.128/28170.3.8.129 to 170.3.8.142170.3.8.14314
138170.3.8.144/28170.3.8.145 to 170.3.8.158170.3.8.15914
139170.3.8.160/28170.3.8.161 to 170.3.8.174170.3.8.17514
140170.3.8.176/28170.3.8.177 to 170.3.8.190170.3.8.19114
141170.3.8.192/28170.3.8.193 to 170.3.8.206170.3.8.20714
142170.3.8.208/28170.3.8.209 to 170.3.8.222170.3.8.22314
143170.3.8.224/28170.3.8.225 to 170.3.8.238170.3.8.23914
144170.3.8.240/28170.3.8.241 to 170.3.8.254170.3.8.25514
145170.3.9.0/28170.3.9.1 to 170.3.9.14170.3.9.1514
146170.3.9.16/28170.3.9.17 to 170.3.9.30170.3.9.3114
147170.3.9.32/28170.3.9.33 to 170.3.9.46170.3.9.4714
148170.3.9.48/28170.3.9.49 to 170.3.9.62170.3.9.6314
149170.3.9.64/28170.3.9.65 to 170.3.9.78170.3.9.7914
150170.3.9.80/28170.3.9.81 to 170.3.9.94170.3.9.9514
151170.3.9.96/28170.3.9.97 to 170.3.9.110170.3.9.11114
152170.3.9.112/28170.3.9.113 to 170.3.9.126170.3.9.12714
153170.3.9.128/28170.3.9.129 to 170.3.9.142170.3.9.14314
154170.3.9.144/28170.3.9.145 to 170.3.9.158170.3.9.15914
155170.3.9.160/28170.3.9.161 to 170.3.9.174170.3.9.17514
156170.3.9.176/28170.3.9.177 to 170.3.9.190170.3.9.19114
157170.3.9.192/28170.3.9.193 to 170.3.9.206170.3.9.20714
158170.3.9.208/28170.3.9.209 to 170.3.9.222170.3.9.22314
159170.3.9.224/28170.3.9.225 to 170.3.9.238170.3.9.23914
160170.3.9.240/28170.3.9.241 to 170.3.9.254170.3.9.25514
161170.3.10.0/28170.3.10.1 to 170.3.10.14170.3.10.1514
162170.3.10.16/28170.3.10.17 to 170.3.10.30170.3.10.3114
163170.3.10.32/28170.3.10.33 to 170.3.10.46170.3.10.4714
164170.3.10.48/28170.3.10.49 to 170.3.10.62170.3.10.6314
165170.3.10.64/28170.3.10.65 to 170.3.10.78170.3.10.7914
166170.3.10.80/28170.3.10.81 to 170.3.10.94170.3.10.9514
167170.3.10.96/28170.3.10.97 to 170.3.10.110170.3.10.11114
168170.3.10.112/28170.3.10.113 to 170.3.10.126170.3.10.12714
169170.3.10.128/28170.3.10.129 to 170.3.10.142170.3.10.14314
170170.3.10.144/28170.3.10.145 to 170.3.10.158170.3.10.15914
171170.3.10.160/28170.3.10.161 to 170.3.10.174170.3.10.17514
172170.3.10.176/28170.3.10.177 to 170.3.10.190170.3.10.19114
173170.3.10.192/28170.3.10.193 to 170.3.10.206170.3.10.20714
174170.3.10.208/28170.3.10.209 to 170.3.10.222170.3.10.22314
175170.3.10.224/28170.3.10.225 to 170.3.10.238170.3.10.23914
176170.3.10.240/28170.3.10.241 to 170.3.10.254170.3.10.25514
177170.3.11.0/28170.3.11.1 to 170.3.11.14170.3.11.1514
178170.3.11.16/28170.3.11.17 to 170.3.11.30170.3.11.3114
179170.3.11.32/28170.3.11.33 to 170.3.11.46170.3.11.4714
180170.3.11.48/28170.3.11.49 to 170.3.11.62170.3.11.6314
181170.3.11.64/28170.3.11.65 to 170.3.11.78170.3.11.7914
182170.3.11.80/28170.3.11.81 to 170.3.11.94170.3.11.9514
183170.3.11.96/28170.3.11.97 to 170.3.11.110170.3.11.11114
184170.3.11.112/28170.3.11.113 to 170.3.11.126170.3.11.12714
185170.3.11.128/28170.3.11.129 to 170.3.11.142170.3.11.14314
186170.3.11.144/28170.3.11.145 to 170.3.11.158170.3.11.15914
187170.3.11.160/28170.3.11.161 to 170.3.11.174170.3.11.17514
188170.3.11.176/28170.3.11.177 to 170.3.11.190170.3.11.19114
189170.3.11.192/28170.3.11.193 to 170.3.11.206170.3.11.20714
190170.3.11.208/28170.3.11.209 to 170.3.11.222170.3.11.22314
191170.3.11.224/28170.3.11.225 to 170.3.11.238170.3.11.23914
192170.3.11.240/28170.3.11.241 to 170.3.11.254170.3.11.25514
193170.3.12.0/28170.3.12.1 to 170.3.12.14170.3.12.1514
194170.3.12.16/28170.3.12.17 to 170.3.12.30170.3.12.3114
195170.3.12.32/28170.3.12.33 to 170.3.12.46170.3.12.4714
196170.3.12.48/28170.3.12.49 to 170.3.12.62170.3.12.6314
197170.3.12.64/28170.3.12.65 to 170.3.12.78170.3.12.7914
198170.3.12.80/28170.3.12.81 to 170.3.12.94170.3.12.9514
199170.3.12.96/28170.3.12.97 to 170.3.12.110170.3.12.11114
200170.3.12.112/28170.3.12.113 to 170.3.12.126170.3.12.12714
201170.3.12.128/28170.3.12.129 to 170.3.12.142170.3.12.14314
202170.3.12.144/28170.3.12.145 to 170.3.12.158170.3.12.15914
203170.3.12.160/28170.3.12.161 to 170.3.12.174170.3.12.17514
204170.3.12.176/28170.3.12.177 to 170.3.12.190170.3.12.19114
205170.3.12.192/28170.3.12.193 to 170.3.12.206170.3.12.20714
206170.3.12.208/28170.3.12.209 to 170.3.12.222170.3.12.22314
207170.3.12.224/28170.3.12.225 to 170.3.12.238170.3.12.23914
208170.3.12.240/28170.3.12.241 to 170.3.12.254170.3.12.25514
209170.3.13.0/28170.3.13.1 to 170.3.13.14170.3.13.1514
210170.3.13.16/28170.3.13.17 to 170.3.13.30170.3.13.3114
211170.3.13.32/28170.3.13.33 to 170.3.13.46170.3.13.4714
212170.3.13.48/28170.3.13.49 to 170.3.13.62170.3.13.6314
213170.3.13.64/28170.3.13.65 to 170.3.13.78170.3.13.7914
214170.3.13.80/28170.3.13.81 to 170.3.13.94170.3.13.9514
215170.3.13.96/28170.3.13.97 to 170.3.13.110170.3.13.11114
216170.3.13.112/28170.3.13.113 to 170.3.13.126170.3.13.12714
217170.3.13.128/28170.3.13.129 to 170.3.13.142170.3.13.14314
218170.3.13.144/28170.3.13.145 to 170.3.13.158170.3.13.15914
219170.3.13.160/28170.3.13.161 to 170.3.13.174170.3.13.17514
220170.3.13.176/28170.3.13.177 to 170.3.13.190170.3.13.19114
221170.3.13.192/28170.3.13.193 to 170.3.13.206170.3.13.20714
222170.3.13.208/28170.3.13.209 to 170.3.13.222170.3.13.22314
223170.3.13.224/28170.3.13.225 to 170.3.13.238170.3.13.23914
224170.3.13.240/28170.3.13.241 to 170.3.13.254170.3.13.25514
225170.3.14.0/28170.3.14.1 to 170.3.14.14170.3.14.1514
226170.3.14.16/28170.3.14.17 to 170.3.14.30170.3.14.3114
227170.3.14.32/28170.3.14.33 to 170.3.14.46170.3.14.4714
228170.3.14.48/28170.3.14.49 to 170.3.14.62170.3.14.6314
229170.3.14.64/28170.3.14.65 to 170.3.14.78170.3.14.7914
230170.3.14.80/28170.3.14.81 to 170.3.14.94170.3.14.9514
231170.3.14.96/28170.3.14.97 to 170.3.14.110170.3.14.11114
232170.3.14.112/28170.3.14.113 to 170.3.14.126170.3.14.12714
233170.3.14.128/28170.3.14.129 to 170.3.14.142170.3.14.14314
234170.3.14.144/28170.3.14.145 to 170.3.14.158170.3.14.15914
235170.3.14.160/28170.3.14.161 to 170.3.14.174170.3.14.17514
236170.3.14.176/28170.3.14.177 to 170.3.14.190170.3.14.19114
237170.3.14.192/28170.3.14.193 to 170.3.14.206170.3.14.20714
238170.3.14.208/28170.3.14.209 to 170.3.14.222170.3.14.22314
239170.3.14.224/28170.3.14.225 to 170.3.14.238170.3.14.23914
240170.3.14.240/28170.3.14.241 to 170.3.14.254170.3.14.25514
241170.3.15.0/28170.3.15.1 to 170.3.15.14170.3.15.1514
242170.3.15.16/28170.3.15.17 to 170.3.15.30170.3.15.3114
243170.3.15.32/28170.3.15.33 to 170.3.15.46170.3.15.4714
244170.3.15.48/28170.3.15.49 to 170.3.15.62170.3.15.6314
245170.3.15.64/28170.3.15.65 to 170.3.15.78170.3.15.7914
246170.3.15.80/28170.3.15.81 to 170.3.15.94170.3.15.9514
247170.3.15.96/28170.3.15.97 to 170.3.15.110170.3.15.11114
248170.3.15.112/28170.3.15.113 to 170.3.15.126170.3.15.12714
249170.3.15.128/28170.3.15.129 to 170.3.15.142170.3.15.14314
250170.3.15.144/28170.3.15.145 to 170.3.15.158170.3.15.15914
251170.3.15.160/28170.3.15.161 to 170.3.15.174170.3.15.17514
252170.3.15.176/28170.3.15.177 to 170.3.15.190170.3.15.19114
253170.3.15.192/28170.3.15.193 to 170.3.15.206170.3.15.20714
254170.3.15.208/28170.3.15.209 to 170.3.15.222170.3.15.22314
255170.3.15.224/28170.3.15.225 to 170.3.15.238170.3.15.23914
256170.3.15.240/28170.3.15.241 to 170.3.15.254170.3.15.25514

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.