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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.

Network221.0.0.0/13
Usable hosts524,286
Subnet mask255.248.0.0
Addresses524,288
Network address
221.0.0.0
Broadcast address
221.7.255.255
First usable
221.0.0.1
Last usable
221.7.255.254
Usable hosts
524,286 (524,288 less the network and broadcast addresses)
Subnet mask
255.248.0.0
Wildcard mask
0.7.255.255 (Cisco ACLs, OSPF)
Prefix length
/13
Type
Public public
Old class
C (default /24)
As numbers
Hex DD000000 · Integer 3707764736 to 3708289023
Reverse DNS zones
0.221.in-addr.arpa
1.221.in-addr.arpa
2.221.in-addr.arpa
3.221.in-addr.arpa
4.221.in-addr.arpa
5.221.in-addr.arpa
6.221.in-addr.arpa
7.221.in-addr.arpa
/13 is not on a 8-bit boundary, so it takes 8 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11011101.00000000.00000000.00000000221.0.0.0
Subnet mask11111111.11111000.00000000.00000000255.248.0.0
Network11011101.00000000.00000000.00000000221.0.0.0
Broadcast11011101.00000111.11111111.11111111221.7.255.255
Split into smaller subnets/24
/14 (2)/15 (4)/16 (8)/17 (16)/18 (32)/19 (64)/20 (128)/21 (256)/22 (512)/23 (1,024)/24 (2,048)/25 (4,096)

221.0.0.0/13 makes 2,048 subnets of /24; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1221.0.0.0/24221.0.0.1 to 221.0.0.254221.0.0.255254
2221.0.1.0/24221.0.1.1 to 221.0.1.254221.0.1.255254
3221.0.2.0/24221.0.2.1 to 221.0.2.254221.0.2.255254
4221.0.3.0/24221.0.3.1 to 221.0.3.254221.0.3.255254
5221.0.4.0/24221.0.4.1 to 221.0.4.254221.0.4.255254
6221.0.5.0/24221.0.5.1 to 221.0.5.254221.0.5.255254
7221.0.6.0/24221.0.6.1 to 221.0.6.254221.0.6.255254
8221.0.7.0/24221.0.7.1 to 221.0.7.254221.0.7.255254
9221.0.8.0/24221.0.8.1 to 221.0.8.254221.0.8.255254
10221.0.9.0/24221.0.9.1 to 221.0.9.254221.0.9.255254
11221.0.10.0/24221.0.10.1 to 221.0.10.254221.0.10.255254
12221.0.11.0/24221.0.11.1 to 221.0.11.254221.0.11.255254
13221.0.12.0/24221.0.12.1 to 221.0.12.254221.0.12.255254
14221.0.13.0/24221.0.13.1 to 221.0.13.254221.0.13.255254
15221.0.14.0/24221.0.14.1 to 221.0.14.254221.0.14.255254
16221.0.15.0/24221.0.15.1 to 221.0.15.254221.0.15.255254
17221.0.16.0/24221.0.16.1 to 221.0.16.254221.0.16.255254
18221.0.17.0/24221.0.17.1 to 221.0.17.254221.0.17.255254
19221.0.18.0/24221.0.18.1 to 221.0.18.254221.0.18.255254
20221.0.19.0/24221.0.19.1 to 221.0.19.254221.0.19.255254
21221.0.20.0/24221.0.20.1 to 221.0.20.254221.0.20.255254
22221.0.21.0/24221.0.21.1 to 221.0.21.254221.0.21.255254
23221.0.22.0/24221.0.22.1 to 221.0.22.254221.0.22.255254
24221.0.23.0/24221.0.23.1 to 221.0.23.254221.0.23.255254
25221.0.24.0/24221.0.24.1 to 221.0.24.254221.0.24.255254
26221.0.25.0/24221.0.25.1 to 221.0.25.254221.0.25.255254
27221.0.26.0/24221.0.26.1 to 221.0.26.254221.0.26.255254
28221.0.27.0/24221.0.27.1 to 221.0.27.254221.0.27.255254
29221.0.28.0/24221.0.28.1 to 221.0.28.254221.0.28.255254
30221.0.29.0/24221.0.29.1 to 221.0.29.254221.0.29.255254
31221.0.30.0/24221.0.30.1 to 221.0.30.254221.0.30.255254
32221.0.31.0/24221.0.31.1 to 221.0.31.254221.0.31.255254
33221.0.32.0/24221.0.32.1 to 221.0.32.254221.0.32.255254
34221.0.33.0/24221.0.33.1 to 221.0.33.254221.0.33.255254
35221.0.34.0/24221.0.34.1 to 221.0.34.254221.0.34.255254
36221.0.35.0/24221.0.35.1 to 221.0.35.254221.0.35.255254
37221.0.36.0/24221.0.36.1 to 221.0.36.254221.0.36.255254
38221.0.37.0/24221.0.37.1 to 221.0.37.254221.0.37.255254
39221.0.38.0/24221.0.38.1 to 221.0.38.254221.0.38.255254
40221.0.39.0/24221.0.39.1 to 221.0.39.254221.0.39.255254
41221.0.40.0/24221.0.40.1 to 221.0.40.254221.0.40.255254
42221.0.41.0/24221.0.41.1 to 221.0.41.254221.0.41.255254
43221.0.42.0/24221.0.42.1 to 221.0.42.254221.0.42.255254
44221.0.43.0/24221.0.43.1 to 221.0.43.254221.0.43.255254
45221.0.44.0/24221.0.44.1 to 221.0.44.254221.0.44.255254
46221.0.45.0/24221.0.45.1 to 221.0.45.254221.0.45.255254
47221.0.46.0/24221.0.46.1 to 221.0.46.254221.0.46.255254
48221.0.47.0/24221.0.47.1 to 221.0.47.254221.0.47.255254
49221.0.48.0/24221.0.48.1 to 221.0.48.254221.0.48.255254
50221.0.49.0/24221.0.49.1 to 221.0.49.254221.0.49.255254
51221.0.50.0/24221.0.50.1 to 221.0.50.254221.0.50.255254
52221.0.51.0/24221.0.51.1 to 221.0.51.254221.0.51.255254
53221.0.52.0/24221.0.52.1 to 221.0.52.254221.0.52.255254
54221.0.53.0/24221.0.53.1 to 221.0.53.254221.0.53.255254
55221.0.54.0/24221.0.54.1 to 221.0.54.254221.0.54.255254
56221.0.55.0/24221.0.55.1 to 221.0.55.254221.0.55.255254
57221.0.56.0/24221.0.56.1 to 221.0.56.254221.0.56.255254
58221.0.57.0/24221.0.57.1 to 221.0.57.254221.0.57.255254
59221.0.58.0/24221.0.58.1 to 221.0.58.254221.0.58.255254
60221.0.59.0/24221.0.59.1 to 221.0.59.254221.0.59.255254
61221.0.60.0/24221.0.60.1 to 221.0.60.254221.0.60.255254
62221.0.61.0/24221.0.61.1 to 221.0.61.254221.0.61.255254
63221.0.62.0/24221.0.62.1 to 221.0.62.254221.0.62.255254
64221.0.63.0/24221.0.63.1 to 221.0.63.254221.0.63.255254
65221.0.64.0/24221.0.64.1 to 221.0.64.254221.0.64.255254
66221.0.65.0/24221.0.65.1 to 221.0.65.254221.0.65.255254
67221.0.66.0/24221.0.66.1 to 221.0.66.254221.0.66.255254
68221.0.67.0/24221.0.67.1 to 221.0.67.254221.0.67.255254
69221.0.68.0/24221.0.68.1 to 221.0.68.254221.0.68.255254
70221.0.69.0/24221.0.69.1 to 221.0.69.254221.0.69.255254
71221.0.70.0/24221.0.70.1 to 221.0.70.254221.0.70.255254
72221.0.71.0/24221.0.71.1 to 221.0.71.254221.0.71.255254
73221.0.72.0/24221.0.72.1 to 221.0.72.254221.0.72.255254
74221.0.73.0/24221.0.73.1 to 221.0.73.254221.0.73.255254
75221.0.74.0/24221.0.74.1 to 221.0.74.254221.0.74.255254
76221.0.75.0/24221.0.75.1 to 221.0.75.254221.0.75.255254
77221.0.76.0/24221.0.76.1 to 221.0.76.254221.0.76.255254
78221.0.77.0/24221.0.77.1 to 221.0.77.254221.0.77.255254
79221.0.78.0/24221.0.78.1 to 221.0.78.254221.0.78.255254
80221.0.79.0/24221.0.79.1 to 221.0.79.254221.0.79.255254
81221.0.80.0/24221.0.80.1 to 221.0.80.254221.0.80.255254
82221.0.81.0/24221.0.81.1 to 221.0.81.254221.0.81.255254
83221.0.82.0/24221.0.82.1 to 221.0.82.254221.0.82.255254
84221.0.83.0/24221.0.83.1 to 221.0.83.254221.0.83.255254
85221.0.84.0/24221.0.84.1 to 221.0.84.254221.0.84.255254
86221.0.85.0/24221.0.85.1 to 221.0.85.254221.0.85.255254
87221.0.86.0/24221.0.86.1 to 221.0.86.254221.0.86.255254
88221.0.87.0/24221.0.87.1 to 221.0.87.254221.0.87.255254
89221.0.88.0/24221.0.88.1 to 221.0.88.254221.0.88.255254
90221.0.89.0/24221.0.89.1 to 221.0.89.254221.0.89.255254
91221.0.90.0/24221.0.90.1 to 221.0.90.254221.0.90.255254
92221.0.91.0/24221.0.91.1 to 221.0.91.254221.0.91.255254
93221.0.92.0/24221.0.92.1 to 221.0.92.254221.0.92.255254
94221.0.93.0/24221.0.93.1 to 221.0.93.254221.0.93.255254
95221.0.94.0/24221.0.94.1 to 221.0.94.254221.0.94.255254
96221.0.95.0/24221.0.95.1 to 221.0.95.254221.0.95.255254
97221.0.96.0/24221.0.96.1 to 221.0.96.254221.0.96.255254
98221.0.97.0/24221.0.97.1 to 221.0.97.254221.0.97.255254
99221.0.98.0/24221.0.98.1 to 221.0.98.254221.0.98.255254
100221.0.99.0/24221.0.99.1 to 221.0.99.254221.0.99.255254
101221.0.100.0/24221.0.100.1 to 221.0.100.254221.0.100.255254
102221.0.101.0/24221.0.101.1 to 221.0.101.254221.0.101.255254
103221.0.102.0/24221.0.102.1 to 221.0.102.254221.0.102.255254
104221.0.103.0/24221.0.103.1 to 221.0.103.254221.0.103.255254
105221.0.104.0/24221.0.104.1 to 221.0.104.254221.0.104.255254
106221.0.105.0/24221.0.105.1 to 221.0.105.254221.0.105.255254
107221.0.106.0/24221.0.106.1 to 221.0.106.254221.0.106.255254
108221.0.107.0/24221.0.107.1 to 221.0.107.254221.0.107.255254
109221.0.108.0/24221.0.108.1 to 221.0.108.254221.0.108.255254
110221.0.109.0/24221.0.109.1 to 221.0.109.254221.0.109.255254
111221.0.110.0/24221.0.110.1 to 221.0.110.254221.0.110.255254
112221.0.111.0/24221.0.111.1 to 221.0.111.254221.0.111.255254
113221.0.112.0/24221.0.112.1 to 221.0.112.254221.0.112.255254
114221.0.113.0/24221.0.113.1 to 221.0.113.254221.0.113.255254
115221.0.114.0/24221.0.114.1 to 221.0.114.254221.0.114.255254
116221.0.115.0/24221.0.115.1 to 221.0.115.254221.0.115.255254
117221.0.116.0/24221.0.116.1 to 221.0.116.254221.0.116.255254
118221.0.117.0/24221.0.117.1 to 221.0.117.254221.0.117.255254
119221.0.118.0/24221.0.118.1 to 221.0.118.254221.0.118.255254
120221.0.119.0/24221.0.119.1 to 221.0.119.254221.0.119.255254
121221.0.120.0/24221.0.120.1 to 221.0.120.254221.0.120.255254
122221.0.121.0/24221.0.121.1 to 221.0.121.254221.0.121.255254
123221.0.122.0/24221.0.122.1 to 221.0.122.254221.0.122.255254
124221.0.123.0/24221.0.123.1 to 221.0.123.254221.0.123.255254
125221.0.124.0/24221.0.124.1 to 221.0.124.254221.0.124.255254
126221.0.125.0/24221.0.125.1 to 221.0.125.254221.0.125.255254
127221.0.126.0/24221.0.126.1 to 221.0.126.254221.0.126.255254
128221.0.127.0/24221.0.127.1 to 221.0.127.254221.0.127.255254
129221.0.128.0/24221.0.128.1 to 221.0.128.254221.0.128.255254
130221.0.129.0/24221.0.129.1 to 221.0.129.254221.0.129.255254
131221.0.130.0/24221.0.130.1 to 221.0.130.254221.0.130.255254
132221.0.131.0/24221.0.131.1 to 221.0.131.254221.0.131.255254
133221.0.132.0/24221.0.132.1 to 221.0.132.254221.0.132.255254
134221.0.133.0/24221.0.133.1 to 221.0.133.254221.0.133.255254
135221.0.134.0/24221.0.134.1 to 221.0.134.254221.0.134.255254
136221.0.135.0/24221.0.135.1 to 221.0.135.254221.0.135.255254
137221.0.136.0/24221.0.136.1 to 221.0.136.254221.0.136.255254
138221.0.137.0/24221.0.137.1 to 221.0.137.254221.0.137.255254
139221.0.138.0/24221.0.138.1 to 221.0.138.254221.0.138.255254
140221.0.139.0/24221.0.139.1 to 221.0.139.254221.0.139.255254
141221.0.140.0/24221.0.140.1 to 221.0.140.254221.0.140.255254
142221.0.141.0/24221.0.141.1 to 221.0.141.254221.0.141.255254
143221.0.142.0/24221.0.142.1 to 221.0.142.254221.0.142.255254
144221.0.143.0/24221.0.143.1 to 221.0.143.254221.0.143.255254
145221.0.144.0/24221.0.144.1 to 221.0.144.254221.0.144.255254
146221.0.145.0/24221.0.145.1 to 221.0.145.254221.0.145.255254
147221.0.146.0/24221.0.146.1 to 221.0.146.254221.0.146.255254
148221.0.147.0/24221.0.147.1 to 221.0.147.254221.0.147.255254
149221.0.148.0/24221.0.148.1 to 221.0.148.254221.0.148.255254
150221.0.149.0/24221.0.149.1 to 221.0.149.254221.0.149.255254
151221.0.150.0/24221.0.150.1 to 221.0.150.254221.0.150.255254
152221.0.151.0/24221.0.151.1 to 221.0.151.254221.0.151.255254
153221.0.152.0/24221.0.152.1 to 221.0.152.254221.0.152.255254
154221.0.153.0/24221.0.153.1 to 221.0.153.254221.0.153.255254
155221.0.154.0/24221.0.154.1 to 221.0.154.254221.0.154.255254
156221.0.155.0/24221.0.155.1 to 221.0.155.254221.0.155.255254
157221.0.156.0/24221.0.156.1 to 221.0.156.254221.0.156.255254
158221.0.157.0/24221.0.157.1 to 221.0.157.254221.0.157.255254
159221.0.158.0/24221.0.158.1 to 221.0.158.254221.0.158.255254
160221.0.159.0/24221.0.159.1 to 221.0.159.254221.0.159.255254
161221.0.160.0/24221.0.160.1 to 221.0.160.254221.0.160.255254
162221.0.161.0/24221.0.161.1 to 221.0.161.254221.0.161.255254
163221.0.162.0/24221.0.162.1 to 221.0.162.254221.0.162.255254
164221.0.163.0/24221.0.163.1 to 221.0.163.254221.0.163.255254
165221.0.164.0/24221.0.164.1 to 221.0.164.254221.0.164.255254
166221.0.165.0/24221.0.165.1 to 221.0.165.254221.0.165.255254
167221.0.166.0/24221.0.166.1 to 221.0.166.254221.0.166.255254
168221.0.167.0/24221.0.167.1 to 221.0.167.254221.0.167.255254
169221.0.168.0/24221.0.168.1 to 221.0.168.254221.0.168.255254
170221.0.169.0/24221.0.169.1 to 221.0.169.254221.0.169.255254
171221.0.170.0/24221.0.170.1 to 221.0.170.254221.0.170.255254
172221.0.171.0/24221.0.171.1 to 221.0.171.254221.0.171.255254
173221.0.172.0/24221.0.172.1 to 221.0.172.254221.0.172.255254
174221.0.173.0/24221.0.173.1 to 221.0.173.254221.0.173.255254
175221.0.174.0/24221.0.174.1 to 221.0.174.254221.0.174.255254
176221.0.175.0/24221.0.175.1 to 221.0.175.254221.0.175.255254
177221.0.176.0/24221.0.176.1 to 221.0.176.254221.0.176.255254
178221.0.177.0/24221.0.177.1 to 221.0.177.254221.0.177.255254
179221.0.178.0/24221.0.178.1 to 221.0.178.254221.0.178.255254
180221.0.179.0/24221.0.179.1 to 221.0.179.254221.0.179.255254
181221.0.180.0/24221.0.180.1 to 221.0.180.254221.0.180.255254
182221.0.181.0/24221.0.181.1 to 221.0.181.254221.0.181.255254
183221.0.182.0/24221.0.182.1 to 221.0.182.254221.0.182.255254
184221.0.183.0/24221.0.183.1 to 221.0.183.254221.0.183.255254
185221.0.184.0/24221.0.184.1 to 221.0.184.254221.0.184.255254
186221.0.185.0/24221.0.185.1 to 221.0.185.254221.0.185.255254
187221.0.186.0/24221.0.186.1 to 221.0.186.254221.0.186.255254
188221.0.187.0/24221.0.187.1 to 221.0.187.254221.0.187.255254
189221.0.188.0/24221.0.188.1 to 221.0.188.254221.0.188.255254
190221.0.189.0/24221.0.189.1 to 221.0.189.254221.0.189.255254
191221.0.190.0/24221.0.190.1 to 221.0.190.254221.0.190.255254
192221.0.191.0/24221.0.191.1 to 221.0.191.254221.0.191.255254
193221.0.192.0/24221.0.192.1 to 221.0.192.254221.0.192.255254
194221.0.193.0/24221.0.193.1 to 221.0.193.254221.0.193.255254
195221.0.194.0/24221.0.194.1 to 221.0.194.254221.0.194.255254
196221.0.195.0/24221.0.195.1 to 221.0.195.254221.0.195.255254
197221.0.196.0/24221.0.196.1 to 221.0.196.254221.0.196.255254
198221.0.197.0/24221.0.197.1 to 221.0.197.254221.0.197.255254
199221.0.198.0/24221.0.198.1 to 221.0.198.254221.0.198.255254
200221.0.199.0/24221.0.199.1 to 221.0.199.254221.0.199.255254
201221.0.200.0/24221.0.200.1 to 221.0.200.254221.0.200.255254
202221.0.201.0/24221.0.201.1 to 221.0.201.254221.0.201.255254
203221.0.202.0/24221.0.202.1 to 221.0.202.254221.0.202.255254
204221.0.203.0/24221.0.203.1 to 221.0.203.254221.0.203.255254
205221.0.204.0/24221.0.204.1 to 221.0.204.254221.0.204.255254
206221.0.205.0/24221.0.205.1 to 221.0.205.254221.0.205.255254
207221.0.206.0/24221.0.206.1 to 221.0.206.254221.0.206.255254
208221.0.207.0/24221.0.207.1 to 221.0.207.254221.0.207.255254
209221.0.208.0/24221.0.208.1 to 221.0.208.254221.0.208.255254
210221.0.209.0/24221.0.209.1 to 221.0.209.254221.0.209.255254
211221.0.210.0/24221.0.210.1 to 221.0.210.254221.0.210.255254
212221.0.211.0/24221.0.211.1 to 221.0.211.254221.0.211.255254
213221.0.212.0/24221.0.212.1 to 221.0.212.254221.0.212.255254
214221.0.213.0/24221.0.213.1 to 221.0.213.254221.0.213.255254
215221.0.214.0/24221.0.214.1 to 221.0.214.254221.0.214.255254
216221.0.215.0/24221.0.215.1 to 221.0.215.254221.0.215.255254
217221.0.216.0/24221.0.216.1 to 221.0.216.254221.0.216.255254
218221.0.217.0/24221.0.217.1 to 221.0.217.254221.0.217.255254
219221.0.218.0/24221.0.218.1 to 221.0.218.254221.0.218.255254
220221.0.219.0/24221.0.219.1 to 221.0.219.254221.0.219.255254
221221.0.220.0/24221.0.220.1 to 221.0.220.254221.0.220.255254
222221.0.221.0/24221.0.221.1 to 221.0.221.254221.0.221.255254
223221.0.222.0/24221.0.222.1 to 221.0.222.254221.0.222.255254
224221.0.223.0/24221.0.223.1 to 221.0.223.254221.0.223.255254
225221.0.224.0/24221.0.224.1 to 221.0.224.254221.0.224.255254
226221.0.225.0/24221.0.225.1 to 221.0.225.254221.0.225.255254
227221.0.226.0/24221.0.226.1 to 221.0.226.254221.0.226.255254
228221.0.227.0/24221.0.227.1 to 221.0.227.254221.0.227.255254
229221.0.228.0/24221.0.228.1 to 221.0.228.254221.0.228.255254
230221.0.229.0/24221.0.229.1 to 221.0.229.254221.0.229.255254
231221.0.230.0/24221.0.230.1 to 221.0.230.254221.0.230.255254
232221.0.231.0/24221.0.231.1 to 221.0.231.254221.0.231.255254
233221.0.232.0/24221.0.232.1 to 221.0.232.254221.0.232.255254
234221.0.233.0/24221.0.233.1 to 221.0.233.254221.0.233.255254
235221.0.234.0/24221.0.234.1 to 221.0.234.254221.0.234.255254
236221.0.235.0/24221.0.235.1 to 221.0.235.254221.0.235.255254
237221.0.236.0/24221.0.236.1 to 221.0.236.254221.0.236.255254
238221.0.237.0/24221.0.237.1 to 221.0.237.254221.0.237.255254
239221.0.238.0/24221.0.238.1 to 221.0.238.254221.0.238.255254
240221.0.239.0/24221.0.239.1 to 221.0.239.254221.0.239.255254
241221.0.240.0/24221.0.240.1 to 221.0.240.254221.0.240.255254
242221.0.241.0/24221.0.241.1 to 221.0.241.254221.0.241.255254
243221.0.242.0/24221.0.242.1 to 221.0.242.254221.0.242.255254
244221.0.243.0/24221.0.243.1 to 221.0.243.254221.0.243.255254
245221.0.244.0/24221.0.244.1 to 221.0.244.254221.0.244.255254
246221.0.245.0/24221.0.245.1 to 221.0.245.254221.0.245.255254
247221.0.246.0/24221.0.246.1 to 221.0.246.254221.0.246.255254
248221.0.247.0/24221.0.247.1 to 221.0.247.254221.0.247.255254
249221.0.248.0/24221.0.248.1 to 221.0.248.254221.0.248.255254
250221.0.249.0/24221.0.249.1 to 221.0.249.254221.0.249.255254
251221.0.250.0/24221.0.250.1 to 221.0.250.254221.0.250.255254
252221.0.251.0/24221.0.251.1 to 221.0.251.254221.0.251.255254
253221.0.252.0/24221.0.252.1 to 221.0.252.254221.0.252.255254
254221.0.253.0/24221.0.253.1 to 221.0.253.254221.0.253.255254
255221.0.254.0/24221.0.254.1 to 221.0.254.254221.0.254.255254
256221.0.255.0/24221.0.255.1 to 221.0.255.254221.0.255.255254

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.