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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.

Network205.85.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
205.85.0.0
Broadcast address
205.85.255.255
First usable
205.85.0.1
Last usable
205.85.255.254
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
C (default /24)
As numbers
Hex CD550000 · Integer 3444899840 to 3444965375
Reverse DNS zone
85.205.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001101.01010101..00000000.00000000205.85.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network11001101.01010101..00000000.00000000205.85.0.0
Broadcast11001101.01010101..11111111.11111111205.85.255.255
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)

205.85.0.0/16 makes 256 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1205.85.0.0/24205.85.0.1 to 205.85.0.254205.85.0.255254
2205.85.1.0/24205.85.1.1 to 205.85.1.254205.85.1.255254
3205.85.2.0/24205.85.2.1 to 205.85.2.254205.85.2.255254
4205.85.3.0/24205.85.3.1 to 205.85.3.254205.85.3.255254
5205.85.4.0/24205.85.4.1 to 205.85.4.254205.85.4.255254
6205.85.5.0/24205.85.5.1 to 205.85.5.254205.85.5.255254
7205.85.6.0/24205.85.6.1 to 205.85.6.254205.85.6.255254
8205.85.7.0/24205.85.7.1 to 205.85.7.254205.85.7.255254
9205.85.8.0/24205.85.8.1 to 205.85.8.254205.85.8.255254
10205.85.9.0/24205.85.9.1 to 205.85.9.254205.85.9.255254
11205.85.10.0/24205.85.10.1 to 205.85.10.254205.85.10.255254
12205.85.11.0/24205.85.11.1 to 205.85.11.254205.85.11.255254
13205.85.12.0/24205.85.12.1 to 205.85.12.254205.85.12.255254
14205.85.13.0/24205.85.13.1 to 205.85.13.254205.85.13.255254
15205.85.14.0/24205.85.14.1 to 205.85.14.254205.85.14.255254
16205.85.15.0/24205.85.15.1 to 205.85.15.254205.85.15.255254
17205.85.16.0/24205.85.16.1 to 205.85.16.254205.85.16.255254
18205.85.17.0/24205.85.17.1 to 205.85.17.254205.85.17.255254
19205.85.18.0/24205.85.18.1 to 205.85.18.254205.85.18.255254
20205.85.19.0/24205.85.19.1 to 205.85.19.254205.85.19.255254
21205.85.20.0/24205.85.20.1 to 205.85.20.254205.85.20.255254
22205.85.21.0/24205.85.21.1 to 205.85.21.254205.85.21.255254
23205.85.22.0/24205.85.22.1 to 205.85.22.254205.85.22.255254
24205.85.23.0/24205.85.23.1 to 205.85.23.254205.85.23.255254
25205.85.24.0/24205.85.24.1 to 205.85.24.254205.85.24.255254
26205.85.25.0/24205.85.25.1 to 205.85.25.254205.85.25.255254
27205.85.26.0/24205.85.26.1 to 205.85.26.254205.85.26.255254
28205.85.27.0/24205.85.27.1 to 205.85.27.254205.85.27.255254
29205.85.28.0/24205.85.28.1 to 205.85.28.254205.85.28.255254
30205.85.29.0/24205.85.29.1 to 205.85.29.254205.85.29.255254
31205.85.30.0/24205.85.30.1 to 205.85.30.254205.85.30.255254
32205.85.31.0/24205.85.31.1 to 205.85.31.254205.85.31.255254
33205.85.32.0/24205.85.32.1 to 205.85.32.254205.85.32.255254
34205.85.33.0/24205.85.33.1 to 205.85.33.254205.85.33.255254
35205.85.34.0/24205.85.34.1 to 205.85.34.254205.85.34.255254
36205.85.35.0/24205.85.35.1 to 205.85.35.254205.85.35.255254
37205.85.36.0/24205.85.36.1 to 205.85.36.254205.85.36.255254
38205.85.37.0/24205.85.37.1 to 205.85.37.254205.85.37.255254
39205.85.38.0/24205.85.38.1 to 205.85.38.254205.85.38.255254
40205.85.39.0/24205.85.39.1 to 205.85.39.254205.85.39.255254
41205.85.40.0/24205.85.40.1 to 205.85.40.254205.85.40.255254
42205.85.41.0/24205.85.41.1 to 205.85.41.254205.85.41.255254
43205.85.42.0/24205.85.42.1 to 205.85.42.254205.85.42.255254
44205.85.43.0/24205.85.43.1 to 205.85.43.254205.85.43.255254
45205.85.44.0/24205.85.44.1 to 205.85.44.254205.85.44.255254
46205.85.45.0/24205.85.45.1 to 205.85.45.254205.85.45.255254
47205.85.46.0/24205.85.46.1 to 205.85.46.254205.85.46.255254
48205.85.47.0/24205.85.47.1 to 205.85.47.254205.85.47.255254
49205.85.48.0/24205.85.48.1 to 205.85.48.254205.85.48.255254
50205.85.49.0/24205.85.49.1 to 205.85.49.254205.85.49.255254
51205.85.50.0/24205.85.50.1 to 205.85.50.254205.85.50.255254
52205.85.51.0/24205.85.51.1 to 205.85.51.254205.85.51.255254
53205.85.52.0/24205.85.52.1 to 205.85.52.254205.85.52.255254
54205.85.53.0/24205.85.53.1 to 205.85.53.254205.85.53.255254
55205.85.54.0/24205.85.54.1 to 205.85.54.254205.85.54.255254
56205.85.55.0/24205.85.55.1 to 205.85.55.254205.85.55.255254
57205.85.56.0/24205.85.56.1 to 205.85.56.254205.85.56.255254
58205.85.57.0/24205.85.57.1 to 205.85.57.254205.85.57.255254
59205.85.58.0/24205.85.58.1 to 205.85.58.254205.85.58.255254
60205.85.59.0/24205.85.59.1 to 205.85.59.254205.85.59.255254
61205.85.60.0/24205.85.60.1 to 205.85.60.254205.85.60.255254
62205.85.61.0/24205.85.61.1 to 205.85.61.254205.85.61.255254
63205.85.62.0/24205.85.62.1 to 205.85.62.254205.85.62.255254
64205.85.63.0/24205.85.63.1 to 205.85.63.254205.85.63.255254
65205.85.64.0/24205.85.64.1 to 205.85.64.254205.85.64.255254
66205.85.65.0/24205.85.65.1 to 205.85.65.254205.85.65.255254
67205.85.66.0/24205.85.66.1 to 205.85.66.254205.85.66.255254
68205.85.67.0/24205.85.67.1 to 205.85.67.254205.85.67.255254
69205.85.68.0/24205.85.68.1 to 205.85.68.254205.85.68.255254
70205.85.69.0/24205.85.69.1 to 205.85.69.254205.85.69.255254
71205.85.70.0/24205.85.70.1 to 205.85.70.254205.85.70.255254
72205.85.71.0/24205.85.71.1 to 205.85.71.254205.85.71.255254
73205.85.72.0/24205.85.72.1 to 205.85.72.254205.85.72.255254
74205.85.73.0/24205.85.73.1 to 205.85.73.254205.85.73.255254
75205.85.74.0/24205.85.74.1 to 205.85.74.254205.85.74.255254
76205.85.75.0/24205.85.75.1 to 205.85.75.254205.85.75.255254
77205.85.76.0/24205.85.76.1 to 205.85.76.254205.85.76.255254
78205.85.77.0/24205.85.77.1 to 205.85.77.254205.85.77.255254
79205.85.78.0/24205.85.78.1 to 205.85.78.254205.85.78.255254
80205.85.79.0/24205.85.79.1 to 205.85.79.254205.85.79.255254
81205.85.80.0/24205.85.80.1 to 205.85.80.254205.85.80.255254
82205.85.81.0/24205.85.81.1 to 205.85.81.254205.85.81.255254
83205.85.82.0/24205.85.82.1 to 205.85.82.254205.85.82.255254
84205.85.83.0/24205.85.83.1 to 205.85.83.254205.85.83.255254
85205.85.84.0/24205.85.84.1 to 205.85.84.254205.85.84.255254
86205.85.85.0/24205.85.85.1 to 205.85.85.254205.85.85.255254
87205.85.86.0/24205.85.86.1 to 205.85.86.254205.85.86.255254
88205.85.87.0/24205.85.87.1 to 205.85.87.254205.85.87.255254
89205.85.88.0/24205.85.88.1 to 205.85.88.254205.85.88.255254
90205.85.89.0/24205.85.89.1 to 205.85.89.254205.85.89.255254
91205.85.90.0/24205.85.90.1 to 205.85.90.254205.85.90.255254
92205.85.91.0/24205.85.91.1 to 205.85.91.254205.85.91.255254
93205.85.92.0/24205.85.92.1 to 205.85.92.254205.85.92.255254
94205.85.93.0/24205.85.93.1 to 205.85.93.254205.85.93.255254
95205.85.94.0/24205.85.94.1 to 205.85.94.254205.85.94.255254
96205.85.95.0/24205.85.95.1 to 205.85.95.254205.85.95.255254
97205.85.96.0/24205.85.96.1 to 205.85.96.254205.85.96.255254
98205.85.97.0/24205.85.97.1 to 205.85.97.254205.85.97.255254
99205.85.98.0/24205.85.98.1 to 205.85.98.254205.85.98.255254
100205.85.99.0/24205.85.99.1 to 205.85.99.254205.85.99.255254
101205.85.100.0/24205.85.100.1 to 205.85.100.254205.85.100.255254
102205.85.101.0/24205.85.101.1 to 205.85.101.254205.85.101.255254
103205.85.102.0/24205.85.102.1 to 205.85.102.254205.85.102.255254
104205.85.103.0/24205.85.103.1 to 205.85.103.254205.85.103.255254
105205.85.104.0/24205.85.104.1 to 205.85.104.254205.85.104.255254
106205.85.105.0/24205.85.105.1 to 205.85.105.254205.85.105.255254
107205.85.106.0/24205.85.106.1 to 205.85.106.254205.85.106.255254
108205.85.107.0/24205.85.107.1 to 205.85.107.254205.85.107.255254
109205.85.108.0/24205.85.108.1 to 205.85.108.254205.85.108.255254
110205.85.109.0/24205.85.109.1 to 205.85.109.254205.85.109.255254
111205.85.110.0/24205.85.110.1 to 205.85.110.254205.85.110.255254
112205.85.111.0/24205.85.111.1 to 205.85.111.254205.85.111.255254
113205.85.112.0/24205.85.112.1 to 205.85.112.254205.85.112.255254
114205.85.113.0/24205.85.113.1 to 205.85.113.254205.85.113.255254
115205.85.114.0/24205.85.114.1 to 205.85.114.254205.85.114.255254
116205.85.115.0/24205.85.115.1 to 205.85.115.254205.85.115.255254
117205.85.116.0/24205.85.116.1 to 205.85.116.254205.85.116.255254
118205.85.117.0/24205.85.117.1 to 205.85.117.254205.85.117.255254
119205.85.118.0/24205.85.118.1 to 205.85.118.254205.85.118.255254
120205.85.119.0/24205.85.119.1 to 205.85.119.254205.85.119.255254
121205.85.120.0/24205.85.120.1 to 205.85.120.254205.85.120.255254
122205.85.121.0/24205.85.121.1 to 205.85.121.254205.85.121.255254
123205.85.122.0/24205.85.122.1 to 205.85.122.254205.85.122.255254
124205.85.123.0/24205.85.123.1 to 205.85.123.254205.85.123.255254
125205.85.124.0/24205.85.124.1 to 205.85.124.254205.85.124.255254
126205.85.125.0/24205.85.125.1 to 205.85.125.254205.85.125.255254
127205.85.126.0/24205.85.126.1 to 205.85.126.254205.85.126.255254
128205.85.127.0/24205.85.127.1 to 205.85.127.254205.85.127.255254
129205.85.128.0/24205.85.128.1 to 205.85.128.254205.85.128.255254
130205.85.129.0/24205.85.129.1 to 205.85.129.254205.85.129.255254
131205.85.130.0/24205.85.130.1 to 205.85.130.254205.85.130.255254
132205.85.131.0/24205.85.131.1 to 205.85.131.254205.85.131.255254
133205.85.132.0/24205.85.132.1 to 205.85.132.254205.85.132.255254
134205.85.133.0/24205.85.133.1 to 205.85.133.254205.85.133.255254
135205.85.134.0/24205.85.134.1 to 205.85.134.254205.85.134.255254
136205.85.135.0/24205.85.135.1 to 205.85.135.254205.85.135.255254
137205.85.136.0/24205.85.136.1 to 205.85.136.254205.85.136.255254
138205.85.137.0/24205.85.137.1 to 205.85.137.254205.85.137.255254
139205.85.138.0/24205.85.138.1 to 205.85.138.254205.85.138.255254
140205.85.139.0/24205.85.139.1 to 205.85.139.254205.85.139.255254
141205.85.140.0/24205.85.140.1 to 205.85.140.254205.85.140.255254
142205.85.141.0/24205.85.141.1 to 205.85.141.254205.85.141.255254
143205.85.142.0/24205.85.142.1 to 205.85.142.254205.85.142.255254
144205.85.143.0/24205.85.143.1 to 205.85.143.254205.85.143.255254
145205.85.144.0/24205.85.144.1 to 205.85.144.254205.85.144.255254
146205.85.145.0/24205.85.145.1 to 205.85.145.254205.85.145.255254
147205.85.146.0/24205.85.146.1 to 205.85.146.254205.85.146.255254
148205.85.147.0/24205.85.147.1 to 205.85.147.254205.85.147.255254
149205.85.148.0/24205.85.148.1 to 205.85.148.254205.85.148.255254
150205.85.149.0/24205.85.149.1 to 205.85.149.254205.85.149.255254
151205.85.150.0/24205.85.150.1 to 205.85.150.254205.85.150.255254
152205.85.151.0/24205.85.151.1 to 205.85.151.254205.85.151.255254
153205.85.152.0/24205.85.152.1 to 205.85.152.254205.85.152.255254
154205.85.153.0/24205.85.153.1 to 205.85.153.254205.85.153.255254
155205.85.154.0/24205.85.154.1 to 205.85.154.254205.85.154.255254
156205.85.155.0/24205.85.155.1 to 205.85.155.254205.85.155.255254
157205.85.156.0/24205.85.156.1 to 205.85.156.254205.85.156.255254
158205.85.157.0/24205.85.157.1 to 205.85.157.254205.85.157.255254
159205.85.158.0/24205.85.158.1 to 205.85.158.254205.85.158.255254
160205.85.159.0/24205.85.159.1 to 205.85.159.254205.85.159.255254
161205.85.160.0/24205.85.160.1 to 205.85.160.254205.85.160.255254
162205.85.161.0/24205.85.161.1 to 205.85.161.254205.85.161.255254
163205.85.162.0/24205.85.162.1 to 205.85.162.254205.85.162.255254
164205.85.163.0/24205.85.163.1 to 205.85.163.254205.85.163.255254
165205.85.164.0/24205.85.164.1 to 205.85.164.254205.85.164.255254
166205.85.165.0/24205.85.165.1 to 205.85.165.254205.85.165.255254
167205.85.166.0/24205.85.166.1 to 205.85.166.254205.85.166.255254
168205.85.167.0/24205.85.167.1 to 205.85.167.254205.85.167.255254
169205.85.168.0/24205.85.168.1 to 205.85.168.254205.85.168.255254
170205.85.169.0/24205.85.169.1 to 205.85.169.254205.85.169.255254
171205.85.170.0/24205.85.170.1 to 205.85.170.254205.85.170.255254
172205.85.171.0/24205.85.171.1 to 205.85.171.254205.85.171.255254
173205.85.172.0/24205.85.172.1 to 205.85.172.254205.85.172.255254
174205.85.173.0/24205.85.173.1 to 205.85.173.254205.85.173.255254
175205.85.174.0/24205.85.174.1 to 205.85.174.254205.85.174.255254
176205.85.175.0/24205.85.175.1 to 205.85.175.254205.85.175.255254
177205.85.176.0/24205.85.176.1 to 205.85.176.254205.85.176.255254
178205.85.177.0/24205.85.177.1 to 205.85.177.254205.85.177.255254
179205.85.178.0/24205.85.178.1 to 205.85.178.254205.85.178.255254
180205.85.179.0/24205.85.179.1 to 205.85.179.254205.85.179.255254
181205.85.180.0/24205.85.180.1 to 205.85.180.254205.85.180.255254
182205.85.181.0/24205.85.181.1 to 205.85.181.254205.85.181.255254
183205.85.182.0/24205.85.182.1 to 205.85.182.254205.85.182.255254
184205.85.183.0/24205.85.183.1 to 205.85.183.254205.85.183.255254
185205.85.184.0/24205.85.184.1 to 205.85.184.254205.85.184.255254
186205.85.185.0/24205.85.185.1 to 205.85.185.254205.85.185.255254
187205.85.186.0/24205.85.186.1 to 205.85.186.254205.85.186.255254
188205.85.187.0/24205.85.187.1 to 205.85.187.254205.85.187.255254
189205.85.188.0/24205.85.188.1 to 205.85.188.254205.85.188.255254
190205.85.189.0/24205.85.189.1 to 205.85.189.254205.85.189.255254
191205.85.190.0/24205.85.190.1 to 205.85.190.254205.85.190.255254
192205.85.191.0/24205.85.191.1 to 205.85.191.254205.85.191.255254
193205.85.192.0/24205.85.192.1 to 205.85.192.254205.85.192.255254
194205.85.193.0/24205.85.193.1 to 205.85.193.254205.85.193.255254
195205.85.194.0/24205.85.194.1 to 205.85.194.254205.85.194.255254
196205.85.195.0/24205.85.195.1 to 205.85.195.254205.85.195.255254
197205.85.196.0/24205.85.196.1 to 205.85.196.254205.85.196.255254
198205.85.197.0/24205.85.197.1 to 205.85.197.254205.85.197.255254
199205.85.198.0/24205.85.198.1 to 205.85.198.254205.85.198.255254
200205.85.199.0/24205.85.199.1 to 205.85.199.254205.85.199.255254
201205.85.200.0/24205.85.200.1 to 205.85.200.254205.85.200.255254
202205.85.201.0/24205.85.201.1 to 205.85.201.254205.85.201.255254
203205.85.202.0/24205.85.202.1 to 205.85.202.254205.85.202.255254
204205.85.203.0/24205.85.203.1 to 205.85.203.254205.85.203.255254
205205.85.204.0/24205.85.204.1 to 205.85.204.254205.85.204.255254
206205.85.205.0/24205.85.205.1 to 205.85.205.254205.85.205.255254
207205.85.206.0/24205.85.206.1 to 205.85.206.254205.85.206.255254
208205.85.207.0/24205.85.207.1 to 205.85.207.254205.85.207.255254
209205.85.208.0/24205.85.208.1 to 205.85.208.254205.85.208.255254
210205.85.209.0/24205.85.209.1 to 205.85.209.254205.85.209.255254
211205.85.210.0/24205.85.210.1 to 205.85.210.254205.85.210.255254
212205.85.211.0/24205.85.211.1 to 205.85.211.254205.85.211.255254
213205.85.212.0/24205.85.212.1 to 205.85.212.254205.85.212.255254
214205.85.213.0/24205.85.213.1 to 205.85.213.254205.85.213.255254
215205.85.214.0/24205.85.214.1 to 205.85.214.254205.85.214.255254
216205.85.215.0/24205.85.215.1 to 205.85.215.254205.85.215.255254
217205.85.216.0/24205.85.216.1 to 205.85.216.254205.85.216.255254
218205.85.217.0/24205.85.217.1 to 205.85.217.254205.85.217.255254
219205.85.218.0/24205.85.218.1 to 205.85.218.254205.85.218.255254
220205.85.219.0/24205.85.219.1 to 205.85.219.254205.85.219.255254
221205.85.220.0/24205.85.220.1 to 205.85.220.254205.85.220.255254
222205.85.221.0/24205.85.221.1 to 205.85.221.254205.85.221.255254
223205.85.222.0/24205.85.222.1 to 205.85.222.254205.85.222.255254
224205.85.223.0/24205.85.223.1 to 205.85.223.254205.85.223.255254
225205.85.224.0/24205.85.224.1 to 205.85.224.254205.85.224.255254
226205.85.225.0/24205.85.225.1 to 205.85.225.254205.85.225.255254
227205.85.226.0/24205.85.226.1 to 205.85.226.254205.85.226.255254
228205.85.227.0/24205.85.227.1 to 205.85.227.254205.85.227.255254
229205.85.228.0/24205.85.228.1 to 205.85.228.254205.85.228.255254
230205.85.229.0/24205.85.229.1 to 205.85.229.254205.85.229.255254
231205.85.230.0/24205.85.230.1 to 205.85.230.254205.85.230.255254
232205.85.231.0/24205.85.231.1 to 205.85.231.254205.85.231.255254
233205.85.232.0/24205.85.232.1 to 205.85.232.254205.85.232.255254
234205.85.233.0/24205.85.233.1 to 205.85.233.254205.85.233.255254
235205.85.234.0/24205.85.234.1 to 205.85.234.254205.85.234.255254
236205.85.235.0/24205.85.235.1 to 205.85.235.254205.85.235.255254
237205.85.236.0/24205.85.236.1 to 205.85.236.254205.85.236.255254
238205.85.237.0/24205.85.237.1 to 205.85.237.254205.85.237.255254
239205.85.238.0/24205.85.238.1 to 205.85.238.254205.85.238.255254
240205.85.239.0/24205.85.239.1 to 205.85.239.254205.85.239.255254
241205.85.240.0/24205.85.240.1 to 205.85.240.254205.85.240.255254
242205.85.241.0/24205.85.241.1 to 205.85.241.254205.85.241.255254
243205.85.242.0/24205.85.242.1 to 205.85.242.254205.85.242.255254
244205.85.243.0/24205.85.243.1 to 205.85.243.254205.85.243.255254
245205.85.244.0/24205.85.244.1 to 205.85.244.254205.85.244.255254
246205.85.245.0/24205.85.245.1 to 205.85.245.254205.85.245.255254
247205.85.246.0/24205.85.246.1 to 205.85.246.254205.85.246.255254
248205.85.247.0/24205.85.247.1 to 205.85.247.254205.85.247.255254
249205.85.248.0/24205.85.248.1 to 205.85.248.254205.85.248.255254
250205.85.249.0/24205.85.249.1 to 205.85.249.254205.85.249.255254
251205.85.250.0/24205.85.250.1 to 205.85.250.254205.85.250.255254
252205.85.251.0/24205.85.251.1 to 205.85.251.254205.85.251.255254
253205.85.252.0/24205.85.252.1 to 205.85.252.254205.85.252.255254
254205.85.253.0/24205.85.253.1 to 205.85.253.254205.85.253.255254
255205.85.254.0/24205.85.254.1 to 205.85.254.254205.85.254.255254
256205.85.255.0/24205.85.255.1 to 205.85.255.254205.85.255.255254

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.