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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.

Network145.3.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
145.3.0.0
Broadcast address
145.3.255.255
First usable
145.3.0.1
Last usable
145.3.255.254
Usable hosts
65,534 (65,536 less the network and broadcast addresses)
Subnet mask
255.255.0.0
Wildcard mask
0.0.255.255 (Cisco ACLs, OSPF)
Prefix length
/16
Type
Public public
Old class
B (default /16)
As numbers
Hex 91030000 · Integer 2432892928 to 2432958463
Reverse DNS zone
3.145.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10010001.00000011..00000000.00000000145.3.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network10010001.00000011..00000000.00000000145.3.0.0
Broadcast10010001.00000011..11111111.11111111145.3.255.255
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/21 (32)/22 (64)/23 (128)/24 (256)/25 (512)/26 (1,024)/27 (2,048)/28 (4,096)

145.3.0.0/16 makes 256 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1145.3.0.0/24145.3.0.1 to 145.3.0.254145.3.0.255254
2145.3.1.0/24145.3.1.1 to 145.3.1.254145.3.1.255254
3145.3.2.0/24145.3.2.1 to 145.3.2.254145.3.2.255254
4145.3.3.0/24145.3.3.1 to 145.3.3.254145.3.3.255254
5145.3.4.0/24145.3.4.1 to 145.3.4.254145.3.4.255254
6145.3.5.0/24145.3.5.1 to 145.3.5.254145.3.5.255254
7145.3.6.0/24145.3.6.1 to 145.3.6.254145.3.6.255254
8145.3.7.0/24145.3.7.1 to 145.3.7.254145.3.7.255254
9145.3.8.0/24145.3.8.1 to 145.3.8.254145.3.8.255254
10145.3.9.0/24145.3.9.1 to 145.3.9.254145.3.9.255254
11145.3.10.0/24145.3.10.1 to 145.3.10.254145.3.10.255254
12145.3.11.0/24145.3.11.1 to 145.3.11.254145.3.11.255254
13145.3.12.0/24145.3.12.1 to 145.3.12.254145.3.12.255254
14145.3.13.0/24145.3.13.1 to 145.3.13.254145.3.13.255254
15145.3.14.0/24145.3.14.1 to 145.3.14.254145.3.14.255254
16145.3.15.0/24145.3.15.1 to 145.3.15.254145.3.15.255254
17145.3.16.0/24145.3.16.1 to 145.3.16.254145.3.16.255254
18145.3.17.0/24145.3.17.1 to 145.3.17.254145.3.17.255254
19145.3.18.0/24145.3.18.1 to 145.3.18.254145.3.18.255254
20145.3.19.0/24145.3.19.1 to 145.3.19.254145.3.19.255254
21145.3.20.0/24145.3.20.1 to 145.3.20.254145.3.20.255254
22145.3.21.0/24145.3.21.1 to 145.3.21.254145.3.21.255254
23145.3.22.0/24145.3.22.1 to 145.3.22.254145.3.22.255254
24145.3.23.0/24145.3.23.1 to 145.3.23.254145.3.23.255254
25145.3.24.0/24145.3.24.1 to 145.3.24.254145.3.24.255254
26145.3.25.0/24145.3.25.1 to 145.3.25.254145.3.25.255254
27145.3.26.0/24145.3.26.1 to 145.3.26.254145.3.26.255254
28145.3.27.0/24145.3.27.1 to 145.3.27.254145.3.27.255254
29145.3.28.0/24145.3.28.1 to 145.3.28.254145.3.28.255254
30145.3.29.0/24145.3.29.1 to 145.3.29.254145.3.29.255254
31145.3.30.0/24145.3.30.1 to 145.3.30.254145.3.30.255254
32145.3.31.0/24145.3.31.1 to 145.3.31.254145.3.31.255254
33145.3.32.0/24145.3.32.1 to 145.3.32.254145.3.32.255254
34145.3.33.0/24145.3.33.1 to 145.3.33.254145.3.33.255254
35145.3.34.0/24145.3.34.1 to 145.3.34.254145.3.34.255254
36145.3.35.0/24145.3.35.1 to 145.3.35.254145.3.35.255254
37145.3.36.0/24145.3.36.1 to 145.3.36.254145.3.36.255254
38145.3.37.0/24145.3.37.1 to 145.3.37.254145.3.37.255254
39145.3.38.0/24145.3.38.1 to 145.3.38.254145.3.38.255254
40145.3.39.0/24145.3.39.1 to 145.3.39.254145.3.39.255254
41145.3.40.0/24145.3.40.1 to 145.3.40.254145.3.40.255254
42145.3.41.0/24145.3.41.1 to 145.3.41.254145.3.41.255254
43145.3.42.0/24145.3.42.1 to 145.3.42.254145.3.42.255254
44145.3.43.0/24145.3.43.1 to 145.3.43.254145.3.43.255254
45145.3.44.0/24145.3.44.1 to 145.3.44.254145.3.44.255254
46145.3.45.0/24145.3.45.1 to 145.3.45.254145.3.45.255254
47145.3.46.0/24145.3.46.1 to 145.3.46.254145.3.46.255254
48145.3.47.0/24145.3.47.1 to 145.3.47.254145.3.47.255254
49145.3.48.0/24145.3.48.1 to 145.3.48.254145.3.48.255254
50145.3.49.0/24145.3.49.1 to 145.3.49.254145.3.49.255254
51145.3.50.0/24145.3.50.1 to 145.3.50.254145.3.50.255254
52145.3.51.0/24145.3.51.1 to 145.3.51.254145.3.51.255254
53145.3.52.0/24145.3.52.1 to 145.3.52.254145.3.52.255254
54145.3.53.0/24145.3.53.1 to 145.3.53.254145.3.53.255254
55145.3.54.0/24145.3.54.1 to 145.3.54.254145.3.54.255254
56145.3.55.0/24145.3.55.1 to 145.3.55.254145.3.55.255254
57145.3.56.0/24145.3.56.1 to 145.3.56.254145.3.56.255254
58145.3.57.0/24145.3.57.1 to 145.3.57.254145.3.57.255254
59145.3.58.0/24145.3.58.1 to 145.3.58.254145.3.58.255254
60145.3.59.0/24145.3.59.1 to 145.3.59.254145.3.59.255254
61145.3.60.0/24145.3.60.1 to 145.3.60.254145.3.60.255254
62145.3.61.0/24145.3.61.1 to 145.3.61.254145.3.61.255254
63145.3.62.0/24145.3.62.1 to 145.3.62.254145.3.62.255254
64145.3.63.0/24145.3.63.1 to 145.3.63.254145.3.63.255254
65145.3.64.0/24145.3.64.1 to 145.3.64.254145.3.64.255254
66145.3.65.0/24145.3.65.1 to 145.3.65.254145.3.65.255254
67145.3.66.0/24145.3.66.1 to 145.3.66.254145.3.66.255254
68145.3.67.0/24145.3.67.1 to 145.3.67.254145.3.67.255254
69145.3.68.0/24145.3.68.1 to 145.3.68.254145.3.68.255254
70145.3.69.0/24145.3.69.1 to 145.3.69.254145.3.69.255254
71145.3.70.0/24145.3.70.1 to 145.3.70.254145.3.70.255254
72145.3.71.0/24145.3.71.1 to 145.3.71.254145.3.71.255254
73145.3.72.0/24145.3.72.1 to 145.3.72.254145.3.72.255254
74145.3.73.0/24145.3.73.1 to 145.3.73.254145.3.73.255254
75145.3.74.0/24145.3.74.1 to 145.3.74.254145.3.74.255254
76145.3.75.0/24145.3.75.1 to 145.3.75.254145.3.75.255254
77145.3.76.0/24145.3.76.1 to 145.3.76.254145.3.76.255254
78145.3.77.0/24145.3.77.1 to 145.3.77.254145.3.77.255254
79145.3.78.0/24145.3.78.1 to 145.3.78.254145.3.78.255254
80145.3.79.0/24145.3.79.1 to 145.3.79.254145.3.79.255254
81145.3.80.0/24145.3.80.1 to 145.3.80.254145.3.80.255254
82145.3.81.0/24145.3.81.1 to 145.3.81.254145.3.81.255254
83145.3.82.0/24145.3.82.1 to 145.3.82.254145.3.82.255254
84145.3.83.0/24145.3.83.1 to 145.3.83.254145.3.83.255254
85145.3.84.0/24145.3.84.1 to 145.3.84.254145.3.84.255254
86145.3.85.0/24145.3.85.1 to 145.3.85.254145.3.85.255254
87145.3.86.0/24145.3.86.1 to 145.3.86.254145.3.86.255254
88145.3.87.0/24145.3.87.1 to 145.3.87.254145.3.87.255254
89145.3.88.0/24145.3.88.1 to 145.3.88.254145.3.88.255254
90145.3.89.0/24145.3.89.1 to 145.3.89.254145.3.89.255254
91145.3.90.0/24145.3.90.1 to 145.3.90.254145.3.90.255254
92145.3.91.0/24145.3.91.1 to 145.3.91.254145.3.91.255254
93145.3.92.0/24145.3.92.1 to 145.3.92.254145.3.92.255254
94145.3.93.0/24145.3.93.1 to 145.3.93.254145.3.93.255254
95145.3.94.0/24145.3.94.1 to 145.3.94.254145.3.94.255254
96145.3.95.0/24145.3.95.1 to 145.3.95.254145.3.95.255254
97145.3.96.0/24145.3.96.1 to 145.3.96.254145.3.96.255254
98145.3.97.0/24145.3.97.1 to 145.3.97.254145.3.97.255254
99145.3.98.0/24145.3.98.1 to 145.3.98.254145.3.98.255254
100145.3.99.0/24145.3.99.1 to 145.3.99.254145.3.99.255254
101145.3.100.0/24145.3.100.1 to 145.3.100.254145.3.100.255254
102145.3.101.0/24145.3.101.1 to 145.3.101.254145.3.101.255254
103145.3.102.0/24145.3.102.1 to 145.3.102.254145.3.102.255254
104145.3.103.0/24145.3.103.1 to 145.3.103.254145.3.103.255254
105145.3.104.0/24145.3.104.1 to 145.3.104.254145.3.104.255254
106145.3.105.0/24145.3.105.1 to 145.3.105.254145.3.105.255254
107145.3.106.0/24145.3.106.1 to 145.3.106.254145.3.106.255254
108145.3.107.0/24145.3.107.1 to 145.3.107.254145.3.107.255254
109145.3.108.0/24145.3.108.1 to 145.3.108.254145.3.108.255254
110145.3.109.0/24145.3.109.1 to 145.3.109.254145.3.109.255254
111145.3.110.0/24145.3.110.1 to 145.3.110.254145.3.110.255254
112145.3.111.0/24145.3.111.1 to 145.3.111.254145.3.111.255254
113145.3.112.0/24145.3.112.1 to 145.3.112.254145.3.112.255254
114145.3.113.0/24145.3.113.1 to 145.3.113.254145.3.113.255254
115145.3.114.0/24145.3.114.1 to 145.3.114.254145.3.114.255254
116145.3.115.0/24145.3.115.1 to 145.3.115.254145.3.115.255254
117145.3.116.0/24145.3.116.1 to 145.3.116.254145.3.116.255254
118145.3.117.0/24145.3.117.1 to 145.3.117.254145.3.117.255254
119145.3.118.0/24145.3.118.1 to 145.3.118.254145.3.118.255254
120145.3.119.0/24145.3.119.1 to 145.3.119.254145.3.119.255254
121145.3.120.0/24145.3.120.1 to 145.3.120.254145.3.120.255254
122145.3.121.0/24145.3.121.1 to 145.3.121.254145.3.121.255254
123145.3.122.0/24145.3.122.1 to 145.3.122.254145.3.122.255254
124145.3.123.0/24145.3.123.1 to 145.3.123.254145.3.123.255254
125145.3.124.0/24145.3.124.1 to 145.3.124.254145.3.124.255254
126145.3.125.0/24145.3.125.1 to 145.3.125.254145.3.125.255254
127145.3.126.0/24145.3.126.1 to 145.3.126.254145.3.126.255254
128145.3.127.0/24145.3.127.1 to 145.3.127.254145.3.127.255254
129145.3.128.0/24145.3.128.1 to 145.3.128.254145.3.128.255254
130145.3.129.0/24145.3.129.1 to 145.3.129.254145.3.129.255254
131145.3.130.0/24145.3.130.1 to 145.3.130.254145.3.130.255254
132145.3.131.0/24145.3.131.1 to 145.3.131.254145.3.131.255254
133145.3.132.0/24145.3.132.1 to 145.3.132.254145.3.132.255254
134145.3.133.0/24145.3.133.1 to 145.3.133.254145.3.133.255254
135145.3.134.0/24145.3.134.1 to 145.3.134.254145.3.134.255254
136145.3.135.0/24145.3.135.1 to 145.3.135.254145.3.135.255254
137145.3.136.0/24145.3.136.1 to 145.3.136.254145.3.136.255254
138145.3.137.0/24145.3.137.1 to 145.3.137.254145.3.137.255254
139145.3.138.0/24145.3.138.1 to 145.3.138.254145.3.138.255254
140145.3.139.0/24145.3.139.1 to 145.3.139.254145.3.139.255254
141145.3.140.0/24145.3.140.1 to 145.3.140.254145.3.140.255254
142145.3.141.0/24145.3.141.1 to 145.3.141.254145.3.141.255254
143145.3.142.0/24145.3.142.1 to 145.3.142.254145.3.142.255254
144145.3.143.0/24145.3.143.1 to 145.3.143.254145.3.143.255254
145145.3.144.0/24145.3.144.1 to 145.3.144.254145.3.144.255254
146145.3.145.0/24145.3.145.1 to 145.3.145.254145.3.145.255254
147145.3.146.0/24145.3.146.1 to 145.3.146.254145.3.146.255254
148145.3.147.0/24145.3.147.1 to 145.3.147.254145.3.147.255254
149145.3.148.0/24145.3.148.1 to 145.3.148.254145.3.148.255254
150145.3.149.0/24145.3.149.1 to 145.3.149.254145.3.149.255254
151145.3.150.0/24145.3.150.1 to 145.3.150.254145.3.150.255254
152145.3.151.0/24145.3.151.1 to 145.3.151.254145.3.151.255254
153145.3.152.0/24145.3.152.1 to 145.3.152.254145.3.152.255254
154145.3.153.0/24145.3.153.1 to 145.3.153.254145.3.153.255254
155145.3.154.0/24145.3.154.1 to 145.3.154.254145.3.154.255254
156145.3.155.0/24145.3.155.1 to 145.3.155.254145.3.155.255254
157145.3.156.0/24145.3.156.1 to 145.3.156.254145.3.156.255254
158145.3.157.0/24145.3.157.1 to 145.3.157.254145.3.157.255254
159145.3.158.0/24145.3.158.1 to 145.3.158.254145.3.158.255254
160145.3.159.0/24145.3.159.1 to 145.3.159.254145.3.159.255254
161145.3.160.0/24145.3.160.1 to 145.3.160.254145.3.160.255254
162145.3.161.0/24145.3.161.1 to 145.3.161.254145.3.161.255254
163145.3.162.0/24145.3.162.1 to 145.3.162.254145.3.162.255254
164145.3.163.0/24145.3.163.1 to 145.3.163.254145.3.163.255254
165145.3.164.0/24145.3.164.1 to 145.3.164.254145.3.164.255254
166145.3.165.0/24145.3.165.1 to 145.3.165.254145.3.165.255254
167145.3.166.0/24145.3.166.1 to 145.3.166.254145.3.166.255254
168145.3.167.0/24145.3.167.1 to 145.3.167.254145.3.167.255254
169145.3.168.0/24145.3.168.1 to 145.3.168.254145.3.168.255254
170145.3.169.0/24145.3.169.1 to 145.3.169.254145.3.169.255254
171145.3.170.0/24145.3.170.1 to 145.3.170.254145.3.170.255254
172145.3.171.0/24145.3.171.1 to 145.3.171.254145.3.171.255254
173145.3.172.0/24145.3.172.1 to 145.3.172.254145.3.172.255254
174145.3.173.0/24145.3.173.1 to 145.3.173.254145.3.173.255254
175145.3.174.0/24145.3.174.1 to 145.3.174.254145.3.174.255254
176145.3.175.0/24145.3.175.1 to 145.3.175.254145.3.175.255254
177145.3.176.0/24145.3.176.1 to 145.3.176.254145.3.176.255254
178145.3.177.0/24145.3.177.1 to 145.3.177.254145.3.177.255254
179145.3.178.0/24145.3.178.1 to 145.3.178.254145.3.178.255254
180145.3.179.0/24145.3.179.1 to 145.3.179.254145.3.179.255254
181145.3.180.0/24145.3.180.1 to 145.3.180.254145.3.180.255254
182145.3.181.0/24145.3.181.1 to 145.3.181.254145.3.181.255254
183145.3.182.0/24145.3.182.1 to 145.3.182.254145.3.182.255254
184145.3.183.0/24145.3.183.1 to 145.3.183.254145.3.183.255254
185145.3.184.0/24145.3.184.1 to 145.3.184.254145.3.184.255254
186145.3.185.0/24145.3.185.1 to 145.3.185.254145.3.185.255254
187145.3.186.0/24145.3.186.1 to 145.3.186.254145.3.186.255254
188145.3.187.0/24145.3.187.1 to 145.3.187.254145.3.187.255254
189145.3.188.0/24145.3.188.1 to 145.3.188.254145.3.188.255254
190145.3.189.0/24145.3.189.1 to 145.3.189.254145.3.189.255254
191145.3.190.0/24145.3.190.1 to 145.3.190.254145.3.190.255254
192145.3.191.0/24145.3.191.1 to 145.3.191.254145.3.191.255254
193145.3.192.0/24145.3.192.1 to 145.3.192.254145.3.192.255254
194145.3.193.0/24145.3.193.1 to 145.3.193.254145.3.193.255254
195145.3.194.0/24145.3.194.1 to 145.3.194.254145.3.194.255254
196145.3.195.0/24145.3.195.1 to 145.3.195.254145.3.195.255254
197145.3.196.0/24145.3.196.1 to 145.3.196.254145.3.196.255254
198145.3.197.0/24145.3.197.1 to 145.3.197.254145.3.197.255254
199145.3.198.0/24145.3.198.1 to 145.3.198.254145.3.198.255254
200145.3.199.0/24145.3.199.1 to 145.3.199.254145.3.199.255254
201145.3.200.0/24145.3.200.1 to 145.3.200.254145.3.200.255254
202145.3.201.0/24145.3.201.1 to 145.3.201.254145.3.201.255254
203145.3.202.0/24145.3.202.1 to 145.3.202.254145.3.202.255254
204145.3.203.0/24145.3.203.1 to 145.3.203.254145.3.203.255254
205145.3.204.0/24145.3.204.1 to 145.3.204.254145.3.204.255254
206145.3.205.0/24145.3.205.1 to 145.3.205.254145.3.205.255254
207145.3.206.0/24145.3.206.1 to 145.3.206.254145.3.206.255254
208145.3.207.0/24145.3.207.1 to 145.3.207.254145.3.207.255254
209145.3.208.0/24145.3.208.1 to 145.3.208.254145.3.208.255254
210145.3.209.0/24145.3.209.1 to 145.3.209.254145.3.209.255254
211145.3.210.0/24145.3.210.1 to 145.3.210.254145.3.210.255254
212145.3.211.0/24145.3.211.1 to 145.3.211.254145.3.211.255254
213145.3.212.0/24145.3.212.1 to 145.3.212.254145.3.212.255254
214145.3.213.0/24145.3.213.1 to 145.3.213.254145.3.213.255254
215145.3.214.0/24145.3.214.1 to 145.3.214.254145.3.214.255254
216145.3.215.0/24145.3.215.1 to 145.3.215.254145.3.215.255254
217145.3.216.0/24145.3.216.1 to 145.3.216.254145.3.216.255254
218145.3.217.0/24145.3.217.1 to 145.3.217.254145.3.217.255254
219145.3.218.0/24145.3.218.1 to 145.3.218.254145.3.218.255254
220145.3.219.0/24145.3.219.1 to 145.3.219.254145.3.219.255254
221145.3.220.0/24145.3.220.1 to 145.3.220.254145.3.220.255254
222145.3.221.0/24145.3.221.1 to 145.3.221.254145.3.221.255254
223145.3.222.0/24145.3.222.1 to 145.3.222.254145.3.222.255254
224145.3.223.0/24145.3.223.1 to 145.3.223.254145.3.223.255254
225145.3.224.0/24145.3.224.1 to 145.3.224.254145.3.224.255254
226145.3.225.0/24145.3.225.1 to 145.3.225.254145.3.225.255254
227145.3.226.0/24145.3.226.1 to 145.3.226.254145.3.226.255254
228145.3.227.0/24145.3.227.1 to 145.3.227.254145.3.227.255254
229145.3.228.0/24145.3.228.1 to 145.3.228.254145.3.228.255254
230145.3.229.0/24145.3.229.1 to 145.3.229.254145.3.229.255254
231145.3.230.0/24145.3.230.1 to 145.3.230.254145.3.230.255254
232145.3.231.0/24145.3.231.1 to 145.3.231.254145.3.231.255254
233145.3.232.0/24145.3.232.1 to 145.3.232.254145.3.232.255254
234145.3.233.0/24145.3.233.1 to 145.3.233.254145.3.233.255254
235145.3.234.0/24145.3.234.1 to 145.3.234.254145.3.234.255254
236145.3.235.0/24145.3.235.1 to 145.3.235.254145.3.235.255254
237145.3.236.0/24145.3.236.1 to 145.3.236.254145.3.236.255254
238145.3.237.0/24145.3.237.1 to 145.3.237.254145.3.237.255254
239145.3.238.0/24145.3.238.1 to 145.3.238.254145.3.238.255254
240145.3.239.0/24145.3.239.1 to 145.3.239.254145.3.239.255254
241145.3.240.0/24145.3.240.1 to 145.3.240.254145.3.240.255254
242145.3.241.0/24145.3.241.1 to 145.3.241.254145.3.241.255254
243145.3.242.0/24145.3.242.1 to 145.3.242.254145.3.242.255254
244145.3.243.0/24145.3.243.1 to 145.3.243.254145.3.243.255254
245145.3.244.0/24145.3.244.1 to 145.3.244.254145.3.244.255254
246145.3.245.0/24145.3.245.1 to 145.3.245.254145.3.245.255254
247145.3.246.0/24145.3.246.1 to 145.3.246.254145.3.246.255254
248145.3.247.0/24145.3.247.1 to 145.3.247.254145.3.247.255254
249145.3.248.0/24145.3.248.1 to 145.3.248.254145.3.248.255254
250145.3.249.0/24145.3.249.1 to 145.3.249.254145.3.249.255254
251145.3.250.0/24145.3.250.1 to 145.3.250.254145.3.250.255254
252145.3.251.0/24145.3.251.1 to 145.3.251.254145.3.251.255254
253145.3.252.0/24145.3.252.1 to 145.3.252.254145.3.252.255254
254145.3.253.0/24145.3.253.1 to 145.3.253.254145.3.253.255254
255145.3.254.0/24145.3.254.1 to 145.3.254.254145.3.254.255254
256145.3.255.0/24145.3.255.1 to 145.3.255.254145.3.255.255254

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.