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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.

Network204.0.0.0/6
Usable hosts67,108,862
Subnet mask252.0.0.0
Addresses67,108,864
Network address
204.0.0.0
Broadcast address
207.255.255.255
First usable
204.0.0.1
Last usable
207.255.255.254
Usable hosts
67,108,862 (67,108,864 less the network and broadcast addresses)
Subnet mask
252.0.0.0
Wildcard mask
3.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/6
Type
Public public
Old class
C (default /24)
As numbers
Hex CC000000 · Integer 3422552064 to 3489660927
Reverse DNS zones
204.in-addr.arpa
205.in-addr.arpa
206.in-addr.arpa
207.in-addr.arpa
/6 is not on a 8-bit boundary, so it takes 4 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11001100.00000000.00000000.00000000204.0.0.0
Subnet mask11111100.00000000.00000000.00000000252.0.0.0
Network11001100.00000000.00000000.00000000204.0.0.0
Broadcast11001111.11111111.11111111.11111111207.255.255.255
Split into smaller subnets/15
/7 (2)/8 (4)/9 (8)/10 (16)/11 (32)/12 (64)/13 (128)/14 (256)/15 (512)/16 (1,024)/17 (2,048)/18 (4,096)

204.0.0.0/6 makes 512 subnets of /15; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1204.0.0.0/15204.0.0.1 to 204.1.255.254204.1.255.255131,070
2204.2.0.0/15204.2.0.1 to 204.3.255.254204.3.255.255131,070
3204.4.0.0/15204.4.0.1 to 204.5.255.254204.5.255.255131,070
4204.6.0.0/15204.6.0.1 to 204.7.255.254204.7.255.255131,070
5204.8.0.0/15204.8.0.1 to 204.9.255.254204.9.255.255131,070
6204.10.0.0/15204.10.0.1 to 204.11.255.254204.11.255.255131,070
7204.12.0.0/15204.12.0.1 to 204.13.255.254204.13.255.255131,070
8204.14.0.0/15204.14.0.1 to 204.15.255.254204.15.255.255131,070
9204.16.0.0/15204.16.0.1 to 204.17.255.254204.17.255.255131,070
10204.18.0.0/15204.18.0.1 to 204.19.255.254204.19.255.255131,070
11204.20.0.0/15204.20.0.1 to 204.21.255.254204.21.255.255131,070
12204.22.0.0/15204.22.0.1 to 204.23.255.254204.23.255.255131,070
13204.24.0.0/15204.24.0.1 to 204.25.255.254204.25.255.255131,070
14204.26.0.0/15204.26.0.1 to 204.27.255.254204.27.255.255131,070
15204.28.0.0/15204.28.0.1 to 204.29.255.254204.29.255.255131,070
16204.30.0.0/15204.30.0.1 to 204.31.255.254204.31.255.255131,070
17204.32.0.0/15204.32.0.1 to 204.33.255.254204.33.255.255131,070
18204.34.0.0/15204.34.0.1 to 204.35.255.254204.35.255.255131,070
19204.36.0.0/15204.36.0.1 to 204.37.255.254204.37.255.255131,070
20204.38.0.0/15204.38.0.1 to 204.39.255.254204.39.255.255131,070
21204.40.0.0/15204.40.0.1 to 204.41.255.254204.41.255.255131,070
22204.42.0.0/15204.42.0.1 to 204.43.255.254204.43.255.255131,070
23204.44.0.0/15204.44.0.1 to 204.45.255.254204.45.255.255131,070
24204.46.0.0/15204.46.0.1 to 204.47.255.254204.47.255.255131,070
25204.48.0.0/15204.48.0.1 to 204.49.255.254204.49.255.255131,070
26204.50.0.0/15204.50.0.1 to 204.51.255.254204.51.255.255131,070
27204.52.0.0/15204.52.0.1 to 204.53.255.254204.53.255.255131,070
28204.54.0.0/15204.54.0.1 to 204.55.255.254204.55.255.255131,070
29204.56.0.0/15204.56.0.1 to 204.57.255.254204.57.255.255131,070
30204.58.0.0/15204.58.0.1 to 204.59.255.254204.59.255.255131,070
31204.60.0.0/15204.60.0.1 to 204.61.255.254204.61.255.255131,070
32204.62.0.0/15204.62.0.1 to 204.63.255.254204.63.255.255131,070
33204.64.0.0/15204.64.0.1 to 204.65.255.254204.65.255.255131,070
34204.66.0.0/15204.66.0.1 to 204.67.255.254204.67.255.255131,070
35204.68.0.0/15204.68.0.1 to 204.69.255.254204.69.255.255131,070
36204.70.0.0/15204.70.0.1 to 204.71.255.254204.71.255.255131,070
37204.72.0.0/15204.72.0.1 to 204.73.255.254204.73.255.255131,070
38204.74.0.0/15204.74.0.1 to 204.75.255.254204.75.255.255131,070
39204.76.0.0/15204.76.0.1 to 204.77.255.254204.77.255.255131,070
40204.78.0.0/15204.78.0.1 to 204.79.255.254204.79.255.255131,070
41204.80.0.0/15204.80.0.1 to 204.81.255.254204.81.255.255131,070
42204.82.0.0/15204.82.0.1 to 204.83.255.254204.83.255.255131,070
43204.84.0.0/15204.84.0.1 to 204.85.255.254204.85.255.255131,070
44204.86.0.0/15204.86.0.1 to 204.87.255.254204.87.255.255131,070
45204.88.0.0/15204.88.0.1 to 204.89.255.254204.89.255.255131,070
46204.90.0.0/15204.90.0.1 to 204.91.255.254204.91.255.255131,070
47204.92.0.0/15204.92.0.1 to 204.93.255.254204.93.255.255131,070
48204.94.0.0/15204.94.0.1 to 204.95.255.254204.95.255.255131,070
49204.96.0.0/15204.96.0.1 to 204.97.255.254204.97.255.255131,070
50204.98.0.0/15204.98.0.1 to 204.99.255.254204.99.255.255131,070
51204.100.0.0/15204.100.0.1 to 204.101.255.254204.101.255.255131,070
52204.102.0.0/15204.102.0.1 to 204.103.255.254204.103.255.255131,070
53204.104.0.0/15204.104.0.1 to 204.105.255.254204.105.255.255131,070
54204.106.0.0/15204.106.0.1 to 204.107.255.254204.107.255.255131,070
55204.108.0.0/15204.108.0.1 to 204.109.255.254204.109.255.255131,070
56204.110.0.0/15204.110.0.1 to 204.111.255.254204.111.255.255131,070
57204.112.0.0/15204.112.0.1 to 204.113.255.254204.113.255.255131,070
58204.114.0.0/15204.114.0.1 to 204.115.255.254204.115.255.255131,070
59204.116.0.0/15204.116.0.1 to 204.117.255.254204.117.255.255131,070
60204.118.0.0/15204.118.0.1 to 204.119.255.254204.119.255.255131,070
61204.120.0.0/15204.120.0.1 to 204.121.255.254204.121.255.255131,070
62204.122.0.0/15204.122.0.1 to 204.123.255.254204.123.255.255131,070
63204.124.0.0/15204.124.0.1 to 204.125.255.254204.125.255.255131,070
64204.126.0.0/15204.126.0.1 to 204.127.255.254204.127.255.255131,070
65204.128.0.0/15204.128.0.1 to 204.129.255.254204.129.255.255131,070
66204.130.0.0/15204.130.0.1 to 204.131.255.254204.131.255.255131,070
67204.132.0.0/15204.132.0.1 to 204.133.255.254204.133.255.255131,070
68204.134.0.0/15204.134.0.1 to 204.135.255.254204.135.255.255131,070
69204.136.0.0/15204.136.0.1 to 204.137.255.254204.137.255.255131,070
70204.138.0.0/15204.138.0.1 to 204.139.255.254204.139.255.255131,070
71204.140.0.0/15204.140.0.1 to 204.141.255.254204.141.255.255131,070
72204.142.0.0/15204.142.0.1 to 204.143.255.254204.143.255.255131,070
73204.144.0.0/15204.144.0.1 to 204.145.255.254204.145.255.255131,070
74204.146.0.0/15204.146.0.1 to 204.147.255.254204.147.255.255131,070
75204.148.0.0/15204.148.0.1 to 204.149.255.254204.149.255.255131,070
76204.150.0.0/15204.150.0.1 to 204.151.255.254204.151.255.255131,070
77204.152.0.0/15204.152.0.1 to 204.153.255.254204.153.255.255131,070
78204.154.0.0/15204.154.0.1 to 204.155.255.254204.155.255.255131,070
79204.156.0.0/15204.156.0.1 to 204.157.255.254204.157.255.255131,070
80204.158.0.0/15204.158.0.1 to 204.159.255.254204.159.255.255131,070
81204.160.0.0/15204.160.0.1 to 204.161.255.254204.161.255.255131,070
82204.162.0.0/15204.162.0.1 to 204.163.255.254204.163.255.255131,070
83204.164.0.0/15204.164.0.1 to 204.165.255.254204.165.255.255131,070
84204.166.0.0/15204.166.0.1 to 204.167.255.254204.167.255.255131,070
85204.168.0.0/15204.168.0.1 to 204.169.255.254204.169.255.255131,070
86204.170.0.0/15204.170.0.1 to 204.171.255.254204.171.255.255131,070
87204.172.0.0/15204.172.0.1 to 204.173.255.254204.173.255.255131,070
88204.174.0.0/15204.174.0.1 to 204.175.255.254204.175.255.255131,070
89204.176.0.0/15204.176.0.1 to 204.177.255.254204.177.255.255131,070
90204.178.0.0/15204.178.0.1 to 204.179.255.254204.179.255.255131,070
91204.180.0.0/15204.180.0.1 to 204.181.255.254204.181.255.255131,070
92204.182.0.0/15204.182.0.1 to 204.183.255.254204.183.255.255131,070
93204.184.0.0/15204.184.0.1 to 204.185.255.254204.185.255.255131,070
94204.186.0.0/15204.186.0.1 to 204.187.255.254204.187.255.255131,070
95204.188.0.0/15204.188.0.1 to 204.189.255.254204.189.255.255131,070
96204.190.0.0/15204.190.0.1 to 204.191.255.254204.191.255.255131,070
97204.192.0.0/15204.192.0.1 to 204.193.255.254204.193.255.255131,070
98204.194.0.0/15204.194.0.1 to 204.195.255.254204.195.255.255131,070
99204.196.0.0/15204.196.0.1 to 204.197.255.254204.197.255.255131,070
100204.198.0.0/15204.198.0.1 to 204.199.255.254204.199.255.255131,070
101204.200.0.0/15204.200.0.1 to 204.201.255.254204.201.255.255131,070
102204.202.0.0/15204.202.0.1 to 204.203.255.254204.203.255.255131,070
103204.204.0.0/15204.204.0.1 to 204.205.255.254204.205.255.255131,070
104204.206.0.0/15204.206.0.1 to 204.207.255.254204.207.255.255131,070
105204.208.0.0/15204.208.0.1 to 204.209.255.254204.209.255.255131,070
106204.210.0.0/15204.210.0.1 to 204.211.255.254204.211.255.255131,070
107204.212.0.0/15204.212.0.1 to 204.213.255.254204.213.255.255131,070
108204.214.0.0/15204.214.0.1 to 204.215.255.254204.215.255.255131,070
109204.216.0.0/15204.216.0.1 to 204.217.255.254204.217.255.255131,070
110204.218.0.0/15204.218.0.1 to 204.219.255.254204.219.255.255131,070
111204.220.0.0/15204.220.0.1 to 204.221.255.254204.221.255.255131,070
112204.222.0.0/15204.222.0.1 to 204.223.255.254204.223.255.255131,070
113204.224.0.0/15204.224.0.1 to 204.225.255.254204.225.255.255131,070
114204.226.0.0/15204.226.0.1 to 204.227.255.254204.227.255.255131,070
115204.228.0.0/15204.228.0.1 to 204.229.255.254204.229.255.255131,070
116204.230.0.0/15204.230.0.1 to 204.231.255.254204.231.255.255131,070
117204.232.0.0/15204.232.0.1 to 204.233.255.254204.233.255.255131,070
118204.234.0.0/15204.234.0.1 to 204.235.255.254204.235.255.255131,070
119204.236.0.0/15204.236.0.1 to 204.237.255.254204.237.255.255131,070
120204.238.0.0/15204.238.0.1 to 204.239.255.254204.239.255.255131,070
121204.240.0.0/15204.240.0.1 to 204.241.255.254204.241.255.255131,070
122204.242.0.0/15204.242.0.1 to 204.243.255.254204.243.255.255131,070
123204.244.0.0/15204.244.0.1 to 204.245.255.254204.245.255.255131,070
124204.246.0.0/15204.246.0.1 to 204.247.255.254204.247.255.255131,070
125204.248.0.0/15204.248.0.1 to 204.249.255.254204.249.255.255131,070
126204.250.0.0/15204.250.0.1 to 204.251.255.254204.251.255.255131,070
127204.252.0.0/15204.252.0.1 to 204.253.255.254204.253.255.255131,070
128204.254.0.0/15204.254.0.1 to 204.255.255.254204.255.255.255131,070
129205.0.0.0/15205.0.0.1 to 205.1.255.254205.1.255.255131,070
130205.2.0.0/15205.2.0.1 to 205.3.255.254205.3.255.255131,070
131205.4.0.0/15205.4.0.1 to 205.5.255.254205.5.255.255131,070
132205.6.0.0/15205.6.0.1 to 205.7.255.254205.7.255.255131,070
133205.8.0.0/15205.8.0.1 to 205.9.255.254205.9.255.255131,070
134205.10.0.0/15205.10.0.1 to 205.11.255.254205.11.255.255131,070
135205.12.0.0/15205.12.0.1 to 205.13.255.254205.13.255.255131,070
136205.14.0.0/15205.14.0.1 to 205.15.255.254205.15.255.255131,070
137205.16.0.0/15205.16.0.1 to 205.17.255.254205.17.255.255131,070
138205.18.0.0/15205.18.0.1 to 205.19.255.254205.19.255.255131,070
139205.20.0.0/15205.20.0.1 to 205.21.255.254205.21.255.255131,070
140205.22.0.0/15205.22.0.1 to 205.23.255.254205.23.255.255131,070
141205.24.0.0/15205.24.0.1 to 205.25.255.254205.25.255.255131,070
142205.26.0.0/15205.26.0.1 to 205.27.255.254205.27.255.255131,070
143205.28.0.0/15205.28.0.1 to 205.29.255.254205.29.255.255131,070
144205.30.0.0/15205.30.0.1 to 205.31.255.254205.31.255.255131,070
145205.32.0.0/15205.32.0.1 to 205.33.255.254205.33.255.255131,070
146205.34.0.0/15205.34.0.1 to 205.35.255.254205.35.255.255131,070
147205.36.0.0/15205.36.0.1 to 205.37.255.254205.37.255.255131,070
148205.38.0.0/15205.38.0.1 to 205.39.255.254205.39.255.255131,070
149205.40.0.0/15205.40.0.1 to 205.41.255.254205.41.255.255131,070
150205.42.0.0/15205.42.0.1 to 205.43.255.254205.43.255.255131,070
151205.44.0.0/15205.44.0.1 to 205.45.255.254205.45.255.255131,070
152205.46.0.0/15205.46.0.1 to 205.47.255.254205.47.255.255131,070
153205.48.0.0/15205.48.0.1 to 205.49.255.254205.49.255.255131,070
154205.50.0.0/15205.50.0.1 to 205.51.255.254205.51.255.255131,070
155205.52.0.0/15205.52.0.1 to 205.53.255.254205.53.255.255131,070
156205.54.0.0/15205.54.0.1 to 205.55.255.254205.55.255.255131,070
157205.56.0.0/15205.56.0.1 to 205.57.255.254205.57.255.255131,070
158205.58.0.0/15205.58.0.1 to 205.59.255.254205.59.255.255131,070
159205.60.0.0/15205.60.0.1 to 205.61.255.254205.61.255.255131,070
160205.62.0.0/15205.62.0.1 to 205.63.255.254205.63.255.255131,070
161205.64.0.0/15205.64.0.1 to 205.65.255.254205.65.255.255131,070
162205.66.0.0/15205.66.0.1 to 205.67.255.254205.67.255.255131,070
163205.68.0.0/15205.68.0.1 to 205.69.255.254205.69.255.255131,070
164205.70.0.0/15205.70.0.1 to 205.71.255.254205.71.255.255131,070
165205.72.0.0/15205.72.0.1 to 205.73.255.254205.73.255.255131,070
166205.74.0.0/15205.74.0.1 to 205.75.255.254205.75.255.255131,070
167205.76.0.0/15205.76.0.1 to 205.77.255.254205.77.255.255131,070
168205.78.0.0/15205.78.0.1 to 205.79.255.254205.79.255.255131,070
169205.80.0.0/15205.80.0.1 to 205.81.255.254205.81.255.255131,070
170205.82.0.0/15205.82.0.1 to 205.83.255.254205.83.255.255131,070
171205.84.0.0/15205.84.0.1 to 205.85.255.254205.85.255.255131,070
172205.86.0.0/15205.86.0.1 to 205.87.255.254205.87.255.255131,070
173205.88.0.0/15205.88.0.1 to 205.89.255.254205.89.255.255131,070
174205.90.0.0/15205.90.0.1 to 205.91.255.254205.91.255.255131,070
175205.92.0.0/15205.92.0.1 to 205.93.255.254205.93.255.255131,070
176205.94.0.0/15205.94.0.1 to 205.95.255.254205.95.255.255131,070
177205.96.0.0/15205.96.0.1 to 205.97.255.254205.97.255.255131,070
178205.98.0.0/15205.98.0.1 to 205.99.255.254205.99.255.255131,070
179205.100.0.0/15205.100.0.1 to 205.101.255.254205.101.255.255131,070
180205.102.0.0/15205.102.0.1 to 205.103.255.254205.103.255.255131,070
181205.104.0.0/15205.104.0.1 to 205.105.255.254205.105.255.255131,070
182205.106.0.0/15205.106.0.1 to 205.107.255.254205.107.255.255131,070
183205.108.0.0/15205.108.0.1 to 205.109.255.254205.109.255.255131,070
184205.110.0.0/15205.110.0.1 to 205.111.255.254205.111.255.255131,070
185205.112.0.0/15205.112.0.1 to 205.113.255.254205.113.255.255131,070
186205.114.0.0/15205.114.0.1 to 205.115.255.254205.115.255.255131,070
187205.116.0.0/15205.116.0.1 to 205.117.255.254205.117.255.255131,070
188205.118.0.0/15205.118.0.1 to 205.119.255.254205.119.255.255131,070
189205.120.0.0/15205.120.0.1 to 205.121.255.254205.121.255.255131,070
190205.122.0.0/15205.122.0.1 to 205.123.255.254205.123.255.255131,070
191205.124.0.0/15205.124.0.1 to 205.125.255.254205.125.255.255131,070
192205.126.0.0/15205.126.0.1 to 205.127.255.254205.127.255.255131,070
193205.128.0.0/15205.128.0.1 to 205.129.255.254205.129.255.255131,070
194205.130.0.0/15205.130.0.1 to 205.131.255.254205.131.255.255131,070
195205.132.0.0/15205.132.0.1 to 205.133.255.254205.133.255.255131,070
196205.134.0.0/15205.134.0.1 to 205.135.255.254205.135.255.255131,070
197205.136.0.0/15205.136.0.1 to 205.137.255.254205.137.255.255131,070
198205.138.0.0/15205.138.0.1 to 205.139.255.254205.139.255.255131,070
199205.140.0.0/15205.140.0.1 to 205.141.255.254205.141.255.255131,070
200205.142.0.0/15205.142.0.1 to 205.143.255.254205.143.255.255131,070
201205.144.0.0/15205.144.0.1 to 205.145.255.254205.145.255.255131,070
202205.146.0.0/15205.146.0.1 to 205.147.255.254205.147.255.255131,070
203205.148.0.0/15205.148.0.1 to 205.149.255.254205.149.255.255131,070
204205.150.0.0/15205.150.0.1 to 205.151.255.254205.151.255.255131,070
205205.152.0.0/15205.152.0.1 to 205.153.255.254205.153.255.255131,070
206205.154.0.0/15205.154.0.1 to 205.155.255.254205.155.255.255131,070
207205.156.0.0/15205.156.0.1 to 205.157.255.254205.157.255.255131,070
208205.158.0.0/15205.158.0.1 to 205.159.255.254205.159.255.255131,070
209205.160.0.0/15205.160.0.1 to 205.161.255.254205.161.255.255131,070
210205.162.0.0/15205.162.0.1 to 205.163.255.254205.163.255.255131,070
211205.164.0.0/15205.164.0.1 to 205.165.255.254205.165.255.255131,070
212205.166.0.0/15205.166.0.1 to 205.167.255.254205.167.255.255131,070
213205.168.0.0/15205.168.0.1 to 205.169.255.254205.169.255.255131,070
214205.170.0.0/15205.170.0.1 to 205.171.255.254205.171.255.255131,070
215205.172.0.0/15205.172.0.1 to 205.173.255.254205.173.255.255131,070
216205.174.0.0/15205.174.0.1 to 205.175.255.254205.175.255.255131,070
217205.176.0.0/15205.176.0.1 to 205.177.255.254205.177.255.255131,070
218205.178.0.0/15205.178.0.1 to 205.179.255.254205.179.255.255131,070
219205.180.0.0/15205.180.0.1 to 205.181.255.254205.181.255.255131,070
220205.182.0.0/15205.182.0.1 to 205.183.255.254205.183.255.255131,070
221205.184.0.0/15205.184.0.1 to 205.185.255.254205.185.255.255131,070
222205.186.0.0/15205.186.0.1 to 205.187.255.254205.187.255.255131,070
223205.188.0.0/15205.188.0.1 to 205.189.255.254205.189.255.255131,070
224205.190.0.0/15205.190.0.1 to 205.191.255.254205.191.255.255131,070
225205.192.0.0/15205.192.0.1 to 205.193.255.254205.193.255.255131,070
226205.194.0.0/15205.194.0.1 to 205.195.255.254205.195.255.255131,070
227205.196.0.0/15205.196.0.1 to 205.197.255.254205.197.255.255131,070
228205.198.0.0/15205.198.0.1 to 205.199.255.254205.199.255.255131,070
229205.200.0.0/15205.200.0.1 to 205.201.255.254205.201.255.255131,070
230205.202.0.0/15205.202.0.1 to 205.203.255.254205.203.255.255131,070
231205.204.0.0/15205.204.0.1 to 205.205.255.254205.205.255.255131,070
232205.206.0.0/15205.206.0.1 to 205.207.255.254205.207.255.255131,070
233205.208.0.0/15205.208.0.1 to 205.209.255.254205.209.255.255131,070
234205.210.0.0/15205.210.0.1 to 205.211.255.254205.211.255.255131,070
235205.212.0.0/15205.212.0.1 to 205.213.255.254205.213.255.255131,070
236205.214.0.0/15205.214.0.1 to 205.215.255.254205.215.255.255131,070
237205.216.0.0/15205.216.0.1 to 205.217.255.254205.217.255.255131,070
238205.218.0.0/15205.218.0.1 to 205.219.255.254205.219.255.255131,070
239205.220.0.0/15205.220.0.1 to 205.221.255.254205.221.255.255131,070
240205.222.0.0/15205.222.0.1 to 205.223.255.254205.223.255.255131,070
241205.224.0.0/15205.224.0.1 to 205.225.255.254205.225.255.255131,070
242205.226.0.0/15205.226.0.1 to 205.227.255.254205.227.255.255131,070
243205.228.0.0/15205.228.0.1 to 205.229.255.254205.229.255.255131,070
244205.230.0.0/15205.230.0.1 to 205.231.255.254205.231.255.255131,070
245205.232.0.0/15205.232.0.1 to 205.233.255.254205.233.255.255131,070
246205.234.0.0/15205.234.0.1 to 205.235.255.254205.235.255.255131,070
247205.236.0.0/15205.236.0.1 to 205.237.255.254205.237.255.255131,070
248205.238.0.0/15205.238.0.1 to 205.239.255.254205.239.255.255131,070
249205.240.0.0/15205.240.0.1 to 205.241.255.254205.241.255.255131,070
250205.242.0.0/15205.242.0.1 to 205.243.255.254205.243.255.255131,070
251205.244.0.0/15205.244.0.1 to 205.245.255.254205.245.255.255131,070
252205.246.0.0/15205.246.0.1 to 205.247.255.254205.247.255.255131,070
253205.248.0.0/15205.248.0.1 to 205.249.255.254205.249.255.255131,070
254205.250.0.0/15205.250.0.1 to 205.251.255.254205.251.255.255131,070
255205.252.0.0/15205.252.0.1 to 205.253.255.254205.253.255.255131,070
256205.254.0.0/15205.254.0.1 to 205.255.255.254205.255.255.255131,070

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.