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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.

Network207.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
207.0.0.0
Broadcast address
207.63.255.255
First usable
207.0.0.1
Last usable
207.63.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Public public
Old class
C (default /24)
As numbers
Hex CF000000 · Integer 3472883712 to 3477078015
Reverse DNS zones
0.207.in-addr.arpa
1.207.in-addr.arpa
2.207.in-addr.arpa
3.207.in-addr.arpa
4.207.in-addr.arpa
5.207.in-addr.arpa
6.207.in-addr.arpa
7.207.in-addr.arpa
8.207.in-addr.arpa
9.207.in-addr.arpa
10.207.in-addr.arpa
11.207.in-addr.arpa
12.207.in-addr.arpa
13.207.in-addr.arpa
14.207.in-addr.arpa
15.207.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001111.00000000.00000000.00000000207.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network11001111.00000000.00000000.00000000207.0.0.0
Broadcast11001111.00111111.11111111.11111111207.63.255.255
Split into smaller subnets/18
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

207.0.0.0/10 makes 256 subnets of /18.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1207.0.0.0/18207.0.0.1 to 207.0.63.254207.0.63.25516,382
2207.0.64.0/18207.0.64.1 to 207.0.127.254207.0.127.25516,382
3207.0.128.0/18207.0.128.1 to 207.0.191.254207.0.191.25516,382
4207.0.192.0/18207.0.192.1 to 207.0.255.254207.0.255.25516,382
5207.1.0.0/18207.1.0.1 to 207.1.63.254207.1.63.25516,382
6207.1.64.0/18207.1.64.1 to 207.1.127.254207.1.127.25516,382
7207.1.128.0/18207.1.128.1 to 207.1.191.254207.1.191.25516,382
8207.1.192.0/18207.1.192.1 to 207.1.255.254207.1.255.25516,382
9207.2.0.0/18207.2.0.1 to 207.2.63.254207.2.63.25516,382
10207.2.64.0/18207.2.64.1 to 207.2.127.254207.2.127.25516,382
11207.2.128.0/18207.2.128.1 to 207.2.191.254207.2.191.25516,382
12207.2.192.0/18207.2.192.1 to 207.2.255.254207.2.255.25516,382
13207.3.0.0/18207.3.0.1 to 207.3.63.254207.3.63.25516,382
14207.3.64.0/18207.3.64.1 to 207.3.127.254207.3.127.25516,382
15207.3.128.0/18207.3.128.1 to 207.3.191.254207.3.191.25516,382
16207.3.192.0/18207.3.192.1 to 207.3.255.254207.3.255.25516,382
17207.4.0.0/18207.4.0.1 to 207.4.63.254207.4.63.25516,382
18207.4.64.0/18207.4.64.1 to 207.4.127.254207.4.127.25516,382
19207.4.128.0/18207.4.128.1 to 207.4.191.254207.4.191.25516,382
20207.4.192.0/18207.4.192.1 to 207.4.255.254207.4.255.25516,382
21207.5.0.0/18207.5.0.1 to 207.5.63.254207.5.63.25516,382
22207.5.64.0/18207.5.64.1 to 207.5.127.254207.5.127.25516,382
23207.5.128.0/18207.5.128.1 to 207.5.191.254207.5.191.25516,382
24207.5.192.0/18207.5.192.1 to 207.5.255.254207.5.255.25516,382
25207.6.0.0/18207.6.0.1 to 207.6.63.254207.6.63.25516,382
26207.6.64.0/18207.6.64.1 to 207.6.127.254207.6.127.25516,382
27207.6.128.0/18207.6.128.1 to 207.6.191.254207.6.191.25516,382
28207.6.192.0/18207.6.192.1 to 207.6.255.254207.6.255.25516,382
29207.7.0.0/18207.7.0.1 to 207.7.63.254207.7.63.25516,382
30207.7.64.0/18207.7.64.1 to 207.7.127.254207.7.127.25516,382
31207.7.128.0/18207.7.128.1 to 207.7.191.254207.7.191.25516,382
32207.7.192.0/18207.7.192.1 to 207.7.255.254207.7.255.25516,382
33207.8.0.0/18207.8.0.1 to 207.8.63.254207.8.63.25516,382
34207.8.64.0/18207.8.64.1 to 207.8.127.254207.8.127.25516,382
35207.8.128.0/18207.8.128.1 to 207.8.191.254207.8.191.25516,382
36207.8.192.0/18207.8.192.1 to 207.8.255.254207.8.255.25516,382
37207.9.0.0/18207.9.0.1 to 207.9.63.254207.9.63.25516,382
38207.9.64.0/18207.9.64.1 to 207.9.127.254207.9.127.25516,382
39207.9.128.0/18207.9.128.1 to 207.9.191.254207.9.191.25516,382
40207.9.192.0/18207.9.192.1 to 207.9.255.254207.9.255.25516,382
41207.10.0.0/18207.10.0.1 to 207.10.63.254207.10.63.25516,382
42207.10.64.0/18207.10.64.1 to 207.10.127.254207.10.127.25516,382
43207.10.128.0/18207.10.128.1 to 207.10.191.254207.10.191.25516,382
44207.10.192.0/18207.10.192.1 to 207.10.255.254207.10.255.25516,382
45207.11.0.0/18207.11.0.1 to 207.11.63.254207.11.63.25516,382
46207.11.64.0/18207.11.64.1 to 207.11.127.254207.11.127.25516,382
47207.11.128.0/18207.11.128.1 to 207.11.191.254207.11.191.25516,382
48207.11.192.0/18207.11.192.1 to 207.11.255.254207.11.255.25516,382
49207.12.0.0/18207.12.0.1 to 207.12.63.254207.12.63.25516,382
50207.12.64.0/18207.12.64.1 to 207.12.127.254207.12.127.25516,382
51207.12.128.0/18207.12.128.1 to 207.12.191.254207.12.191.25516,382
52207.12.192.0/18207.12.192.1 to 207.12.255.254207.12.255.25516,382
53207.13.0.0/18207.13.0.1 to 207.13.63.254207.13.63.25516,382
54207.13.64.0/18207.13.64.1 to 207.13.127.254207.13.127.25516,382
55207.13.128.0/18207.13.128.1 to 207.13.191.254207.13.191.25516,382
56207.13.192.0/18207.13.192.1 to 207.13.255.254207.13.255.25516,382
57207.14.0.0/18207.14.0.1 to 207.14.63.254207.14.63.25516,382
58207.14.64.0/18207.14.64.1 to 207.14.127.254207.14.127.25516,382
59207.14.128.0/18207.14.128.1 to 207.14.191.254207.14.191.25516,382
60207.14.192.0/18207.14.192.1 to 207.14.255.254207.14.255.25516,382
61207.15.0.0/18207.15.0.1 to 207.15.63.254207.15.63.25516,382
62207.15.64.0/18207.15.64.1 to 207.15.127.254207.15.127.25516,382
63207.15.128.0/18207.15.128.1 to 207.15.191.254207.15.191.25516,382
64207.15.192.0/18207.15.192.1 to 207.15.255.254207.15.255.25516,382
65207.16.0.0/18207.16.0.1 to 207.16.63.254207.16.63.25516,382
66207.16.64.0/18207.16.64.1 to 207.16.127.254207.16.127.25516,382
67207.16.128.0/18207.16.128.1 to 207.16.191.254207.16.191.25516,382
68207.16.192.0/18207.16.192.1 to 207.16.255.254207.16.255.25516,382
69207.17.0.0/18207.17.0.1 to 207.17.63.254207.17.63.25516,382
70207.17.64.0/18207.17.64.1 to 207.17.127.254207.17.127.25516,382
71207.17.128.0/18207.17.128.1 to 207.17.191.254207.17.191.25516,382
72207.17.192.0/18207.17.192.1 to 207.17.255.254207.17.255.25516,382
73207.18.0.0/18207.18.0.1 to 207.18.63.254207.18.63.25516,382
74207.18.64.0/18207.18.64.1 to 207.18.127.254207.18.127.25516,382
75207.18.128.0/18207.18.128.1 to 207.18.191.254207.18.191.25516,382
76207.18.192.0/18207.18.192.1 to 207.18.255.254207.18.255.25516,382
77207.19.0.0/18207.19.0.1 to 207.19.63.254207.19.63.25516,382
78207.19.64.0/18207.19.64.1 to 207.19.127.254207.19.127.25516,382
79207.19.128.0/18207.19.128.1 to 207.19.191.254207.19.191.25516,382
80207.19.192.0/18207.19.192.1 to 207.19.255.254207.19.255.25516,382
81207.20.0.0/18207.20.0.1 to 207.20.63.254207.20.63.25516,382
82207.20.64.0/18207.20.64.1 to 207.20.127.254207.20.127.25516,382
83207.20.128.0/18207.20.128.1 to 207.20.191.254207.20.191.25516,382
84207.20.192.0/18207.20.192.1 to 207.20.255.254207.20.255.25516,382
85207.21.0.0/18207.21.0.1 to 207.21.63.254207.21.63.25516,382
86207.21.64.0/18207.21.64.1 to 207.21.127.254207.21.127.25516,382
87207.21.128.0/18207.21.128.1 to 207.21.191.254207.21.191.25516,382
88207.21.192.0/18207.21.192.1 to 207.21.255.254207.21.255.25516,382
89207.22.0.0/18207.22.0.1 to 207.22.63.254207.22.63.25516,382
90207.22.64.0/18207.22.64.1 to 207.22.127.254207.22.127.25516,382
91207.22.128.0/18207.22.128.1 to 207.22.191.254207.22.191.25516,382
92207.22.192.0/18207.22.192.1 to 207.22.255.254207.22.255.25516,382
93207.23.0.0/18207.23.0.1 to 207.23.63.254207.23.63.25516,382
94207.23.64.0/18207.23.64.1 to 207.23.127.254207.23.127.25516,382
95207.23.128.0/18207.23.128.1 to 207.23.191.254207.23.191.25516,382
96207.23.192.0/18207.23.192.1 to 207.23.255.254207.23.255.25516,382
97207.24.0.0/18207.24.0.1 to 207.24.63.254207.24.63.25516,382
98207.24.64.0/18207.24.64.1 to 207.24.127.254207.24.127.25516,382
99207.24.128.0/18207.24.128.1 to 207.24.191.254207.24.191.25516,382
100207.24.192.0/18207.24.192.1 to 207.24.255.254207.24.255.25516,382
101207.25.0.0/18207.25.0.1 to 207.25.63.254207.25.63.25516,382
102207.25.64.0/18207.25.64.1 to 207.25.127.254207.25.127.25516,382
103207.25.128.0/18207.25.128.1 to 207.25.191.254207.25.191.25516,382
104207.25.192.0/18207.25.192.1 to 207.25.255.254207.25.255.25516,382
105207.26.0.0/18207.26.0.1 to 207.26.63.254207.26.63.25516,382
106207.26.64.0/18207.26.64.1 to 207.26.127.254207.26.127.25516,382
107207.26.128.0/18207.26.128.1 to 207.26.191.254207.26.191.25516,382
108207.26.192.0/18207.26.192.1 to 207.26.255.254207.26.255.25516,382
109207.27.0.0/18207.27.0.1 to 207.27.63.254207.27.63.25516,382
110207.27.64.0/18207.27.64.1 to 207.27.127.254207.27.127.25516,382
111207.27.128.0/18207.27.128.1 to 207.27.191.254207.27.191.25516,382
112207.27.192.0/18207.27.192.1 to 207.27.255.254207.27.255.25516,382
113207.28.0.0/18207.28.0.1 to 207.28.63.254207.28.63.25516,382
114207.28.64.0/18207.28.64.1 to 207.28.127.254207.28.127.25516,382
115207.28.128.0/18207.28.128.1 to 207.28.191.254207.28.191.25516,382
116207.28.192.0/18207.28.192.1 to 207.28.255.254207.28.255.25516,382
117207.29.0.0/18207.29.0.1 to 207.29.63.254207.29.63.25516,382
118207.29.64.0/18207.29.64.1 to 207.29.127.254207.29.127.25516,382
119207.29.128.0/18207.29.128.1 to 207.29.191.254207.29.191.25516,382
120207.29.192.0/18207.29.192.1 to 207.29.255.254207.29.255.25516,382
121207.30.0.0/18207.30.0.1 to 207.30.63.254207.30.63.25516,382
122207.30.64.0/18207.30.64.1 to 207.30.127.254207.30.127.25516,382
123207.30.128.0/18207.30.128.1 to 207.30.191.254207.30.191.25516,382
124207.30.192.0/18207.30.192.1 to 207.30.255.254207.30.255.25516,382
125207.31.0.0/18207.31.0.1 to 207.31.63.254207.31.63.25516,382
126207.31.64.0/18207.31.64.1 to 207.31.127.254207.31.127.25516,382
127207.31.128.0/18207.31.128.1 to 207.31.191.254207.31.191.25516,382
128207.31.192.0/18207.31.192.1 to 207.31.255.254207.31.255.25516,382
129207.32.0.0/18207.32.0.1 to 207.32.63.254207.32.63.25516,382
130207.32.64.0/18207.32.64.1 to 207.32.127.254207.32.127.25516,382
131207.32.128.0/18207.32.128.1 to 207.32.191.254207.32.191.25516,382
132207.32.192.0/18207.32.192.1 to 207.32.255.254207.32.255.25516,382
133207.33.0.0/18207.33.0.1 to 207.33.63.254207.33.63.25516,382
134207.33.64.0/18207.33.64.1 to 207.33.127.254207.33.127.25516,382
135207.33.128.0/18207.33.128.1 to 207.33.191.254207.33.191.25516,382
136207.33.192.0/18207.33.192.1 to 207.33.255.254207.33.255.25516,382
137207.34.0.0/18207.34.0.1 to 207.34.63.254207.34.63.25516,382
138207.34.64.0/18207.34.64.1 to 207.34.127.254207.34.127.25516,382
139207.34.128.0/18207.34.128.1 to 207.34.191.254207.34.191.25516,382
140207.34.192.0/18207.34.192.1 to 207.34.255.254207.34.255.25516,382
141207.35.0.0/18207.35.0.1 to 207.35.63.254207.35.63.25516,382
142207.35.64.0/18207.35.64.1 to 207.35.127.254207.35.127.25516,382
143207.35.128.0/18207.35.128.1 to 207.35.191.254207.35.191.25516,382
144207.35.192.0/18207.35.192.1 to 207.35.255.254207.35.255.25516,382
145207.36.0.0/18207.36.0.1 to 207.36.63.254207.36.63.25516,382
146207.36.64.0/18207.36.64.1 to 207.36.127.254207.36.127.25516,382
147207.36.128.0/18207.36.128.1 to 207.36.191.254207.36.191.25516,382
148207.36.192.0/18207.36.192.1 to 207.36.255.254207.36.255.25516,382
149207.37.0.0/18207.37.0.1 to 207.37.63.254207.37.63.25516,382
150207.37.64.0/18207.37.64.1 to 207.37.127.254207.37.127.25516,382
151207.37.128.0/18207.37.128.1 to 207.37.191.254207.37.191.25516,382
152207.37.192.0/18207.37.192.1 to 207.37.255.254207.37.255.25516,382
153207.38.0.0/18207.38.0.1 to 207.38.63.254207.38.63.25516,382
154207.38.64.0/18207.38.64.1 to 207.38.127.254207.38.127.25516,382
155207.38.128.0/18207.38.128.1 to 207.38.191.254207.38.191.25516,382
156207.38.192.0/18207.38.192.1 to 207.38.255.254207.38.255.25516,382
157207.39.0.0/18207.39.0.1 to 207.39.63.254207.39.63.25516,382
158207.39.64.0/18207.39.64.1 to 207.39.127.254207.39.127.25516,382
159207.39.128.0/18207.39.128.1 to 207.39.191.254207.39.191.25516,382
160207.39.192.0/18207.39.192.1 to 207.39.255.254207.39.255.25516,382
161207.40.0.0/18207.40.0.1 to 207.40.63.254207.40.63.25516,382
162207.40.64.0/18207.40.64.1 to 207.40.127.254207.40.127.25516,382
163207.40.128.0/18207.40.128.1 to 207.40.191.254207.40.191.25516,382
164207.40.192.0/18207.40.192.1 to 207.40.255.254207.40.255.25516,382
165207.41.0.0/18207.41.0.1 to 207.41.63.254207.41.63.25516,382
166207.41.64.0/18207.41.64.1 to 207.41.127.254207.41.127.25516,382
167207.41.128.0/18207.41.128.1 to 207.41.191.254207.41.191.25516,382
168207.41.192.0/18207.41.192.1 to 207.41.255.254207.41.255.25516,382
169207.42.0.0/18207.42.0.1 to 207.42.63.254207.42.63.25516,382
170207.42.64.0/18207.42.64.1 to 207.42.127.254207.42.127.25516,382
171207.42.128.0/18207.42.128.1 to 207.42.191.254207.42.191.25516,382
172207.42.192.0/18207.42.192.1 to 207.42.255.254207.42.255.25516,382
173207.43.0.0/18207.43.0.1 to 207.43.63.254207.43.63.25516,382
174207.43.64.0/18207.43.64.1 to 207.43.127.254207.43.127.25516,382
175207.43.128.0/18207.43.128.1 to 207.43.191.254207.43.191.25516,382
176207.43.192.0/18207.43.192.1 to 207.43.255.254207.43.255.25516,382
177207.44.0.0/18207.44.0.1 to 207.44.63.254207.44.63.25516,382
178207.44.64.0/18207.44.64.1 to 207.44.127.254207.44.127.25516,382
179207.44.128.0/18207.44.128.1 to 207.44.191.254207.44.191.25516,382
180207.44.192.0/18207.44.192.1 to 207.44.255.254207.44.255.25516,382
181207.45.0.0/18207.45.0.1 to 207.45.63.254207.45.63.25516,382
182207.45.64.0/18207.45.64.1 to 207.45.127.254207.45.127.25516,382
183207.45.128.0/18207.45.128.1 to 207.45.191.254207.45.191.25516,382
184207.45.192.0/18207.45.192.1 to 207.45.255.254207.45.255.25516,382
185207.46.0.0/18207.46.0.1 to 207.46.63.254207.46.63.25516,382
186207.46.64.0/18207.46.64.1 to 207.46.127.254207.46.127.25516,382
187207.46.128.0/18207.46.128.1 to 207.46.191.254207.46.191.25516,382
188207.46.192.0/18207.46.192.1 to 207.46.255.254207.46.255.25516,382
189207.47.0.0/18207.47.0.1 to 207.47.63.254207.47.63.25516,382
190207.47.64.0/18207.47.64.1 to 207.47.127.254207.47.127.25516,382
191207.47.128.0/18207.47.128.1 to 207.47.191.254207.47.191.25516,382
192207.47.192.0/18207.47.192.1 to 207.47.255.254207.47.255.25516,382
193207.48.0.0/18207.48.0.1 to 207.48.63.254207.48.63.25516,382
194207.48.64.0/18207.48.64.1 to 207.48.127.254207.48.127.25516,382
195207.48.128.0/18207.48.128.1 to 207.48.191.254207.48.191.25516,382
196207.48.192.0/18207.48.192.1 to 207.48.255.254207.48.255.25516,382
197207.49.0.0/18207.49.0.1 to 207.49.63.254207.49.63.25516,382
198207.49.64.0/18207.49.64.1 to 207.49.127.254207.49.127.25516,382
199207.49.128.0/18207.49.128.1 to 207.49.191.254207.49.191.25516,382
200207.49.192.0/18207.49.192.1 to 207.49.255.254207.49.255.25516,382
201207.50.0.0/18207.50.0.1 to 207.50.63.254207.50.63.25516,382
202207.50.64.0/18207.50.64.1 to 207.50.127.254207.50.127.25516,382
203207.50.128.0/18207.50.128.1 to 207.50.191.254207.50.191.25516,382
204207.50.192.0/18207.50.192.1 to 207.50.255.254207.50.255.25516,382
205207.51.0.0/18207.51.0.1 to 207.51.63.254207.51.63.25516,382
206207.51.64.0/18207.51.64.1 to 207.51.127.254207.51.127.25516,382
207207.51.128.0/18207.51.128.1 to 207.51.191.254207.51.191.25516,382
208207.51.192.0/18207.51.192.1 to 207.51.255.254207.51.255.25516,382
209207.52.0.0/18207.52.0.1 to 207.52.63.254207.52.63.25516,382
210207.52.64.0/18207.52.64.1 to 207.52.127.254207.52.127.25516,382
211207.52.128.0/18207.52.128.1 to 207.52.191.254207.52.191.25516,382
212207.52.192.0/18207.52.192.1 to 207.52.255.254207.52.255.25516,382
213207.53.0.0/18207.53.0.1 to 207.53.63.254207.53.63.25516,382
214207.53.64.0/18207.53.64.1 to 207.53.127.254207.53.127.25516,382
215207.53.128.0/18207.53.128.1 to 207.53.191.254207.53.191.25516,382
216207.53.192.0/18207.53.192.1 to 207.53.255.254207.53.255.25516,382
217207.54.0.0/18207.54.0.1 to 207.54.63.254207.54.63.25516,382
218207.54.64.0/18207.54.64.1 to 207.54.127.254207.54.127.25516,382
219207.54.128.0/18207.54.128.1 to 207.54.191.254207.54.191.25516,382
220207.54.192.0/18207.54.192.1 to 207.54.255.254207.54.255.25516,382
221207.55.0.0/18207.55.0.1 to 207.55.63.254207.55.63.25516,382
222207.55.64.0/18207.55.64.1 to 207.55.127.254207.55.127.25516,382
223207.55.128.0/18207.55.128.1 to 207.55.191.254207.55.191.25516,382
224207.55.192.0/18207.55.192.1 to 207.55.255.254207.55.255.25516,382
225207.56.0.0/18207.56.0.1 to 207.56.63.254207.56.63.25516,382
226207.56.64.0/18207.56.64.1 to 207.56.127.254207.56.127.25516,382
227207.56.128.0/18207.56.128.1 to 207.56.191.254207.56.191.25516,382
228207.56.192.0/18207.56.192.1 to 207.56.255.254207.56.255.25516,382
229207.57.0.0/18207.57.0.1 to 207.57.63.254207.57.63.25516,382
230207.57.64.0/18207.57.64.1 to 207.57.127.254207.57.127.25516,382
231207.57.128.0/18207.57.128.1 to 207.57.191.254207.57.191.25516,382
232207.57.192.0/18207.57.192.1 to 207.57.255.254207.57.255.25516,382
233207.58.0.0/18207.58.0.1 to 207.58.63.254207.58.63.25516,382
234207.58.64.0/18207.58.64.1 to 207.58.127.254207.58.127.25516,382
235207.58.128.0/18207.58.128.1 to 207.58.191.254207.58.191.25516,382
236207.58.192.0/18207.58.192.1 to 207.58.255.254207.58.255.25516,382
237207.59.0.0/18207.59.0.1 to 207.59.63.254207.59.63.25516,382
238207.59.64.0/18207.59.64.1 to 207.59.127.254207.59.127.25516,382
239207.59.128.0/18207.59.128.1 to 207.59.191.254207.59.191.25516,382
240207.59.192.0/18207.59.192.1 to 207.59.255.254207.59.255.25516,382
241207.60.0.0/18207.60.0.1 to 207.60.63.254207.60.63.25516,382
242207.60.64.0/18207.60.64.1 to 207.60.127.254207.60.127.25516,382
243207.60.128.0/18207.60.128.1 to 207.60.191.254207.60.191.25516,382
244207.60.192.0/18207.60.192.1 to 207.60.255.254207.60.255.25516,382
245207.61.0.0/18207.61.0.1 to 207.61.63.254207.61.63.25516,382
246207.61.64.0/18207.61.64.1 to 207.61.127.254207.61.127.25516,382
247207.61.128.0/18207.61.128.1 to 207.61.191.254207.61.191.25516,382
248207.61.192.0/18207.61.192.1 to 207.61.255.254207.61.255.25516,382
249207.62.0.0/18207.62.0.1 to 207.62.63.254207.62.63.25516,382
250207.62.64.0/18207.62.64.1 to 207.62.127.254207.62.127.25516,382
251207.62.128.0/18207.62.128.1 to 207.62.191.254207.62.191.25516,382
252207.62.192.0/18207.62.192.1 to 207.62.255.254207.62.255.25516,382
253207.63.0.0/18207.63.0.1 to 207.63.63.254207.63.63.25516,382
254207.63.64.0/18207.63.64.1 to 207.63.127.254207.63.127.25516,382
255207.63.128.0/18207.63.128.1 to 207.63.191.254207.63.191.25516,382
256207.63.192.0/18207.63.192.1 to 207.63.255.254207.63.255.25516,382

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.