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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/16
/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 1,024 subnets of /16; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1204.0.0.0/16204.0.0.1 to 204.0.255.254204.0.255.25565,534
2204.1.0.0/16204.1.0.1 to 204.1.255.254204.1.255.25565,534
3204.2.0.0/16204.2.0.1 to 204.2.255.254204.2.255.25565,534
4204.3.0.0/16204.3.0.1 to 204.3.255.254204.3.255.25565,534
5204.4.0.0/16204.4.0.1 to 204.4.255.254204.4.255.25565,534
6204.5.0.0/16204.5.0.1 to 204.5.255.254204.5.255.25565,534
7204.6.0.0/16204.6.0.1 to 204.6.255.254204.6.255.25565,534
8204.7.0.0/16204.7.0.1 to 204.7.255.254204.7.255.25565,534
9204.8.0.0/16204.8.0.1 to 204.8.255.254204.8.255.25565,534
10204.9.0.0/16204.9.0.1 to 204.9.255.254204.9.255.25565,534
11204.10.0.0/16204.10.0.1 to 204.10.255.254204.10.255.25565,534
12204.11.0.0/16204.11.0.1 to 204.11.255.254204.11.255.25565,534
13204.12.0.0/16204.12.0.1 to 204.12.255.254204.12.255.25565,534
14204.13.0.0/16204.13.0.1 to 204.13.255.254204.13.255.25565,534
15204.14.0.0/16204.14.0.1 to 204.14.255.254204.14.255.25565,534
16204.15.0.0/16204.15.0.1 to 204.15.255.254204.15.255.25565,534
17204.16.0.0/16204.16.0.1 to 204.16.255.254204.16.255.25565,534
18204.17.0.0/16204.17.0.1 to 204.17.255.254204.17.255.25565,534
19204.18.0.0/16204.18.0.1 to 204.18.255.254204.18.255.25565,534
20204.19.0.0/16204.19.0.1 to 204.19.255.254204.19.255.25565,534
21204.20.0.0/16204.20.0.1 to 204.20.255.254204.20.255.25565,534
22204.21.0.0/16204.21.0.1 to 204.21.255.254204.21.255.25565,534
23204.22.0.0/16204.22.0.1 to 204.22.255.254204.22.255.25565,534
24204.23.0.0/16204.23.0.1 to 204.23.255.254204.23.255.25565,534
25204.24.0.0/16204.24.0.1 to 204.24.255.254204.24.255.25565,534
26204.25.0.0/16204.25.0.1 to 204.25.255.254204.25.255.25565,534
27204.26.0.0/16204.26.0.1 to 204.26.255.254204.26.255.25565,534
28204.27.0.0/16204.27.0.1 to 204.27.255.254204.27.255.25565,534
29204.28.0.0/16204.28.0.1 to 204.28.255.254204.28.255.25565,534
30204.29.0.0/16204.29.0.1 to 204.29.255.254204.29.255.25565,534
31204.30.0.0/16204.30.0.1 to 204.30.255.254204.30.255.25565,534
32204.31.0.0/16204.31.0.1 to 204.31.255.254204.31.255.25565,534
33204.32.0.0/16204.32.0.1 to 204.32.255.254204.32.255.25565,534
34204.33.0.0/16204.33.0.1 to 204.33.255.254204.33.255.25565,534
35204.34.0.0/16204.34.0.1 to 204.34.255.254204.34.255.25565,534
36204.35.0.0/16204.35.0.1 to 204.35.255.254204.35.255.25565,534
37204.36.0.0/16204.36.0.1 to 204.36.255.254204.36.255.25565,534
38204.37.0.0/16204.37.0.1 to 204.37.255.254204.37.255.25565,534
39204.38.0.0/16204.38.0.1 to 204.38.255.254204.38.255.25565,534
40204.39.0.0/16204.39.0.1 to 204.39.255.254204.39.255.25565,534
41204.40.0.0/16204.40.0.1 to 204.40.255.254204.40.255.25565,534
42204.41.0.0/16204.41.0.1 to 204.41.255.254204.41.255.25565,534
43204.42.0.0/16204.42.0.1 to 204.42.255.254204.42.255.25565,534
44204.43.0.0/16204.43.0.1 to 204.43.255.254204.43.255.25565,534
45204.44.0.0/16204.44.0.1 to 204.44.255.254204.44.255.25565,534
46204.45.0.0/16204.45.0.1 to 204.45.255.254204.45.255.25565,534
47204.46.0.0/16204.46.0.1 to 204.46.255.254204.46.255.25565,534
48204.47.0.0/16204.47.0.1 to 204.47.255.254204.47.255.25565,534
49204.48.0.0/16204.48.0.1 to 204.48.255.254204.48.255.25565,534
50204.49.0.0/16204.49.0.1 to 204.49.255.254204.49.255.25565,534
51204.50.0.0/16204.50.0.1 to 204.50.255.254204.50.255.25565,534
52204.51.0.0/16204.51.0.1 to 204.51.255.254204.51.255.25565,534
53204.52.0.0/16204.52.0.1 to 204.52.255.254204.52.255.25565,534
54204.53.0.0/16204.53.0.1 to 204.53.255.254204.53.255.25565,534
55204.54.0.0/16204.54.0.1 to 204.54.255.254204.54.255.25565,534
56204.55.0.0/16204.55.0.1 to 204.55.255.254204.55.255.25565,534
57204.56.0.0/16204.56.0.1 to 204.56.255.254204.56.255.25565,534
58204.57.0.0/16204.57.0.1 to 204.57.255.254204.57.255.25565,534
59204.58.0.0/16204.58.0.1 to 204.58.255.254204.58.255.25565,534
60204.59.0.0/16204.59.0.1 to 204.59.255.254204.59.255.25565,534
61204.60.0.0/16204.60.0.1 to 204.60.255.254204.60.255.25565,534
62204.61.0.0/16204.61.0.1 to 204.61.255.254204.61.255.25565,534
63204.62.0.0/16204.62.0.1 to 204.62.255.254204.62.255.25565,534
64204.63.0.0/16204.63.0.1 to 204.63.255.254204.63.255.25565,534
65204.64.0.0/16204.64.0.1 to 204.64.255.254204.64.255.25565,534
66204.65.0.0/16204.65.0.1 to 204.65.255.254204.65.255.25565,534
67204.66.0.0/16204.66.0.1 to 204.66.255.254204.66.255.25565,534
68204.67.0.0/16204.67.0.1 to 204.67.255.254204.67.255.25565,534
69204.68.0.0/16204.68.0.1 to 204.68.255.254204.68.255.25565,534
70204.69.0.0/16204.69.0.1 to 204.69.255.254204.69.255.25565,534
71204.70.0.0/16204.70.0.1 to 204.70.255.254204.70.255.25565,534
72204.71.0.0/16204.71.0.1 to 204.71.255.254204.71.255.25565,534
73204.72.0.0/16204.72.0.1 to 204.72.255.254204.72.255.25565,534
74204.73.0.0/16204.73.0.1 to 204.73.255.254204.73.255.25565,534
75204.74.0.0/16204.74.0.1 to 204.74.255.254204.74.255.25565,534
76204.75.0.0/16204.75.0.1 to 204.75.255.254204.75.255.25565,534
77204.76.0.0/16204.76.0.1 to 204.76.255.254204.76.255.25565,534
78204.77.0.0/16204.77.0.1 to 204.77.255.254204.77.255.25565,534
79204.78.0.0/16204.78.0.1 to 204.78.255.254204.78.255.25565,534
80204.79.0.0/16204.79.0.1 to 204.79.255.254204.79.255.25565,534
81204.80.0.0/16204.80.0.1 to 204.80.255.254204.80.255.25565,534
82204.81.0.0/16204.81.0.1 to 204.81.255.254204.81.255.25565,534
83204.82.0.0/16204.82.0.1 to 204.82.255.254204.82.255.25565,534
84204.83.0.0/16204.83.0.1 to 204.83.255.254204.83.255.25565,534
85204.84.0.0/16204.84.0.1 to 204.84.255.254204.84.255.25565,534
86204.85.0.0/16204.85.0.1 to 204.85.255.254204.85.255.25565,534
87204.86.0.0/16204.86.0.1 to 204.86.255.254204.86.255.25565,534
88204.87.0.0/16204.87.0.1 to 204.87.255.254204.87.255.25565,534
89204.88.0.0/16204.88.0.1 to 204.88.255.254204.88.255.25565,534
90204.89.0.0/16204.89.0.1 to 204.89.255.254204.89.255.25565,534
91204.90.0.0/16204.90.0.1 to 204.90.255.254204.90.255.25565,534
92204.91.0.0/16204.91.0.1 to 204.91.255.254204.91.255.25565,534
93204.92.0.0/16204.92.0.1 to 204.92.255.254204.92.255.25565,534
94204.93.0.0/16204.93.0.1 to 204.93.255.254204.93.255.25565,534
95204.94.0.0/16204.94.0.1 to 204.94.255.254204.94.255.25565,534
96204.95.0.0/16204.95.0.1 to 204.95.255.254204.95.255.25565,534
97204.96.0.0/16204.96.0.1 to 204.96.255.254204.96.255.25565,534
98204.97.0.0/16204.97.0.1 to 204.97.255.254204.97.255.25565,534
99204.98.0.0/16204.98.0.1 to 204.98.255.254204.98.255.25565,534
100204.99.0.0/16204.99.0.1 to 204.99.255.254204.99.255.25565,534
101204.100.0.0/16204.100.0.1 to 204.100.255.254204.100.255.25565,534
102204.101.0.0/16204.101.0.1 to 204.101.255.254204.101.255.25565,534
103204.102.0.0/16204.102.0.1 to 204.102.255.254204.102.255.25565,534
104204.103.0.0/16204.103.0.1 to 204.103.255.254204.103.255.25565,534
105204.104.0.0/16204.104.0.1 to 204.104.255.254204.104.255.25565,534
106204.105.0.0/16204.105.0.1 to 204.105.255.254204.105.255.25565,534
107204.106.0.0/16204.106.0.1 to 204.106.255.254204.106.255.25565,534
108204.107.0.0/16204.107.0.1 to 204.107.255.254204.107.255.25565,534
109204.108.0.0/16204.108.0.1 to 204.108.255.254204.108.255.25565,534
110204.109.0.0/16204.109.0.1 to 204.109.255.254204.109.255.25565,534
111204.110.0.0/16204.110.0.1 to 204.110.255.254204.110.255.25565,534
112204.111.0.0/16204.111.0.1 to 204.111.255.254204.111.255.25565,534
113204.112.0.0/16204.112.0.1 to 204.112.255.254204.112.255.25565,534
114204.113.0.0/16204.113.0.1 to 204.113.255.254204.113.255.25565,534
115204.114.0.0/16204.114.0.1 to 204.114.255.254204.114.255.25565,534
116204.115.0.0/16204.115.0.1 to 204.115.255.254204.115.255.25565,534
117204.116.0.0/16204.116.0.1 to 204.116.255.254204.116.255.25565,534
118204.117.0.0/16204.117.0.1 to 204.117.255.254204.117.255.25565,534
119204.118.0.0/16204.118.0.1 to 204.118.255.254204.118.255.25565,534
120204.119.0.0/16204.119.0.1 to 204.119.255.254204.119.255.25565,534
121204.120.0.0/16204.120.0.1 to 204.120.255.254204.120.255.25565,534
122204.121.0.0/16204.121.0.1 to 204.121.255.254204.121.255.25565,534
123204.122.0.0/16204.122.0.1 to 204.122.255.254204.122.255.25565,534
124204.123.0.0/16204.123.0.1 to 204.123.255.254204.123.255.25565,534
125204.124.0.0/16204.124.0.1 to 204.124.255.254204.124.255.25565,534
126204.125.0.0/16204.125.0.1 to 204.125.255.254204.125.255.25565,534
127204.126.0.0/16204.126.0.1 to 204.126.255.254204.126.255.25565,534
128204.127.0.0/16204.127.0.1 to 204.127.255.254204.127.255.25565,534
129204.128.0.0/16204.128.0.1 to 204.128.255.254204.128.255.25565,534
130204.129.0.0/16204.129.0.1 to 204.129.255.254204.129.255.25565,534
131204.130.0.0/16204.130.0.1 to 204.130.255.254204.130.255.25565,534
132204.131.0.0/16204.131.0.1 to 204.131.255.254204.131.255.25565,534
133204.132.0.0/16204.132.0.1 to 204.132.255.254204.132.255.25565,534
134204.133.0.0/16204.133.0.1 to 204.133.255.254204.133.255.25565,534
135204.134.0.0/16204.134.0.1 to 204.134.255.254204.134.255.25565,534
136204.135.0.0/16204.135.0.1 to 204.135.255.254204.135.255.25565,534
137204.136.0.0/16204.136.0.1 to 204.136.255.254204.136.255.25565,534
138204.137.0.0/16204.137.0.1 to 204.137.255.254204.137.255.25565,534
139204.138.0.0/16204.138.0.1 to 204.138.255.254204.138.255.25565,534
140204.139.0.0/16204.139.0.1 to 204.139.255.254204.139.255.25565,534
141204.140.0.0/16204.140.0.1 to 204.140.255.254204.140.255.25565,534
142204.141.0.0/16204.141.0.1 to 204.141.255.254204.141.255.25565,534
143204.142.0.0/16204.142.0.1 to 204.142.255.254204.142.255.25565,534
144204.143.0.0/16204.143.0.1 to 204.143.255.254204.143.255.25565,534
145204.144.0.0/16204.144.0.1 to 204.144.255.254204.144.255.25565,534
146204.145.0.0/16204.145.0.1 to 204.145.255.254204.145.255.25565,534
147204.146.0.0/16204.146.0.1 to 204.146.255.254204.146.255.25565,534
148204.147.0.0/16204.147.0.1 to 204.147.255.254204.147.255.25565,534
149204.148.0.0/16204.148.0.1 to 204.148.255.254204.148.255.25565,534
150204.149.0.0/16204.149.0.1 to 204.149.255.254204.149.255.25565,534
151204.150.0.0/16204.150.0.1 to 204.150.255.254204.150.255.25565,534
152204.151.0.0/16204.151.0.1 to 204.151.255.254204.151.255.25565,534
153204.152.0.0/16204.152.0.1 to 204.152.255.254204.152.255.25565,534
154204.153.0.0/16204.153.0.1 to 204.153.255.254204.153.255.25565,534
155204.154.0.0/16204.154.0.1 to 204.154.255.254204.154.255.25565,534
156204.155.0.0/16204.155.0.1 to 204.155.255.254204.155.255.25565,534
157204.156.0.0/16204.156.0.1 to 204.156.255.254204.156.255.25565,534
158204.157.0.0/16204.157.0.1 to 204.157.255.254204.157.255.25565,534
159204.158.0.0/16204.158.0.1 to 204.158.255.254204.158.255.25565,534
160204.159.0.0/16204.159.0.1 to 204.159.255.254204.159.255.25565,534
161204.160.0.0/16204.160.0.1 to 204.160.255.254204.160.255.25565,534
162204.161.0.0/16204.161.0.1 to 204.161.255.254204.161.255.25565,534
163204.162.0.0/16204.162.0.1 to 204.162.255.254204.162.255.25565,534
164204.163.0.0/16204.163.0.1 to 204.163.255.254204.163.255.25565,534
165204.164.0.0/16204.164.0.1 to 204.164.255.254204.164.255.25565,534
166204.165.0.0/16204.165.0.1 to 204.165.255.254204.165.255.25565,534
167204.166.0.0/16204.166.0.1 to 204.166.255.254204.166.255.25565,534
168204.167.0.0/16204.167.0.1 to 204.167.255.254204.167.255.25565,534
169204.168.0.0/16204.168.0.1 to 204.168.255.254204.168.255.25565,534
170204.169.0.0/16204.169.0.1 to 204.169.255.254204.169.255.25565,534
171204.170.0.0/16204.170.0.1 to 204.170.255.254204.170.255.25565,534
172204.171.0.0/16204.171.0.1 to 204.171.255.254204.171.255.25565,534
173204.172.0.0/16204.172.0.1 to 204.172.255.254204.172.255.25565,534
174204.173.0.0/16204.173.0.1 to 204.173.255.254204.173.255.25565,534
175204.174.0.0/16204.174.0.1 to 204.174.255.254204.174.255.25565,534
176204.175.0.0/16204.175.0.1 to 204.175.255.254204.175.255.25565,534
177204.176.0.0/16204.176.0.1 to 204.176.255.254204.176.255.25565,534
178204.177.0.0/16204.177.0.1 to 204.177.255.254204.177.255.25565,534
179204.178.0.0/16204.178.0.1 to 204.178.255.254204.178.255.25565,534
180204.179.0.0/16204.179.0.1 to 204.179.255.254204.179.255.25565,534
181204.180.0.0/16204.180.0.1 to 204.180.255.254204.180.255.25565,534
182204.181.0.0/16204.181.0.1 to 204.181.255.254204.181.255.25565,534
183204.182.0.0/16204.182.0.1 to 204.182.255.254204.182.255.25565,534
184204.183.0.0/16204.183.0.1 to 204.183.255.254204.183.255.25565,534
185204.184.0.0/16204.184.0.1 to 204.184.255.254204.184.255.25565,534
186204.185.0.0/16204.185.0.1 to 204.185.255.254204.185.255.25565,534
187204.186.0.0/16204.186.0.1 to 204.186.255.254204.186.255.25565,534
188204.187.0.0/16204.187.0.1 to 204.187.255.254204.187.255.25565,534
189204.188.0.0/16204.188.0.1 to 204.188.255.254204.188.255.25565,534
190204.189.0.0/16204.189.0.1 to 204.189.255.254204.189.255.25565,534
191204.190.0.0/16204.190.0.1 to 204.190.255.254204.190.255.25565,534
192204.191.0.0/16204.191.0.1 to 204.191.255.254204.191.255.25565,534
193204.192.0.0/16204.192.0.1 to 204.192.255.254204.192.255.25565,534
194204.193.0.0/16204.193.0.1 to 204.193.255.254204.193.255.25565,534
195204.194.0.0/16204.194.0.1 to 204.194.255.254204.194.255.25565,534
196204.195.0.0/16204.195.0.1 to 204.195.255.254204.195.255.25565,534
197204.196.0.0/16204.196.0.1 to 204.196.255.254204.196.255.25565,534
198204.197.0.0/16204.197.0.1 to 204.197.255.254204.197.255.25565,534
199204.198.0.0/16204.198.0.1 to 204.198.255.254204.198.255.25565,534
200204.199.0.0/16204.199.0.1 to 204.199.255.254204.199.255.25565,534
201204.200.0.0/16204.200.0.1 to 204.200.255.254204.200.255.25565,534
202204.201.0.0/16204.201.0.1 to 204.201.255.254204.201.255.25565,534
203204.202.0.0/16204.202.0.1 to 204.202.255.254204.202.255.25565,534
204204.203.0.0/16204.203.0.1 to 204.203.255.254204.203.255.25565,534
205204.204.0.0/16204.204.0.1 to 204.204.255.254204.204.255.25565,534
206204.205.0.0/16204.205.0.1 to 204.205.255.254204.205.255.25565,534
207204.206.0.0/16204.206.0.1 to 204.206.255.254204.206.255.25565,534
208204.207.0.0/16204.207.0.1 to 204.207.255.254204.207.255.25565,534
209204.208.0.0/16204.208.0.1 to 204.208.255.254204.208.255.25565,534
210204.209.0.0/16204.209.0.1 to 204.209.255.254204.209.255.25565,534
211204.210.0.0/16204.210.0.1 to 204.210.255.254204.210.255.25565,534
212204.211.0.0/16204.211.0.1 to 204.211.255.254204.211.255.25565,534
213204.212.0.0/16204.212.0.1 to 204.212.255.254204.212.255.25565,534
214204.213.0.0/16204.213.0.1 to 204.213.255.254204.213.255.25565,534
215204.214.0.0/16204.214.0.1 to 204.214.255.254204.214.255.25565,534
216204.215.0.0/16204.215.0.1 to 204.215.255.254204.215.255.25565,534
217204.216.0.0/16204.216.0.1 to 204.216.255.254204.216.255.25565,534
218204.217.0.0/16204.217.0.1 to 204.217.255.254204.217.255.25565,534
219204.218.0.0/16204.218.0.1 to 204.218.255.254204.218.255.25565,534
220204.219.0.0/16204.219.0.1 to 204.219.255.254204.219.255.25565,534
221204.220.0.0/16204.220.0.1 to 204.220.255.254204.220.255.25565,534
222204.221.0.0/16204.221.0.1 to 204.221.255.254204.221.255.25565,534
223204.222.0.0/16204.222.0.1 to 204.222.255.254204.222.255.25565,534
224204.223.0.0/16204.223.0.1 to 204.223.255.254204.223.255.25565,534
225204.224.0.0/16204.224.0.1 to 204.224.255.254204.224.255.25565,534
226204.225.0.0/16204.225.0.1 to 204.225.255.254204.225.255.25565,534
227204.226.0.0/16204.226.0.1 to 204.226.255.254204.226.255.25565,534
228204.227.0.0/16204.227.0.1 to 204.227.255.254204.227.255.25565,534
229204.228.0.0/16204.228.0.1 to 204.228.255.254204.228.255.25565,534
230204.229.0.0/16204.229.0.1 to 204.229.255.254204.229.255.25565,534
231204.230.0.0/16204.230.0.1 to 204.230.255.254204.230.255.25565,534
232204.231.0.0/16204.231.0.1 to 204.231.255.254204.231.255.25565,534
233204.232.0.0/16204.232.0.1 to 204.232.255.254204.232.255.25565,534
234204.233.0.0/16204.233.0.1 to 204.233.255.254204.233.255.25565,534
235204.234.0.0/16204.234.0.1 to 204.234.255.254204.234.255.25565,534
236204.235.0.0/16204.235.0.1 to 204.235.255.254204.235.255.25565,534
237204.236.0.0/16204.236.0.1 to 204.236.255.254204.236.255.25565,534
238204.237.0.0/16204.237.0.1 to 204.237.255.254204.237.255.25565,534
239204.238.0.0/16204.238.0.1 to 204.238.255.254204.238.255.25565,534
240204.239.0.0/16204.239.0.1 to 204.239.255.254204.239.255.25565,534
241204.240.0.0/16204.240.0.1 to 204.240.255.254204.240.255.25565,534
242204.241.0.0/16204.241.0.1 to 204.241.255.254204.241.255.25565,534
243204.242.0.0/16204.242.0.1 to 204.242.255.254204.242.255.25565,534
244204.243.0.0/16204.243.0.1 to 204.243.255.254204.243.255.25565,534
245204.244.0.0/16204.244.0.1 to 204.244.255.254204.244.255.25565,534
246204.245.0.0/16204.245.0.1 to 204.245.255.254204.245.255.25565,534
247204.246.0.0/16204.246.0.1 to 204.246.255.254204.246.255.25565,534
248204.247.0.0/16204.247.0.1 to 204.247.255.254204.247.255.25565,534
249204.248.0.0/16204.248.0.1 to 204.248.255.254204.248.255.25565,534
250204.249.0.0/16204.249.0.1 to 204.249.255.254204.249.255.25565,534
251204.250.0.0/16204.250.0.1 to 204.250.255.254204.250.255.25565,534
252204.251.0.0/16204.251.0.1 to 204.251.255.254204.251.255.25565,534
253204.252.0.0/16204.252.0.1 to 204.252.255.254204.252.255.25565,534
254204.253.0.0/16204.253.0.1 to 204.253.255.254204.253.255.25565,534
255204.254.0.0/16204.254.0.1 to 204.254.255.254204.254.255.25565,534
256204.255.0.0/16204.255.0.1 to 204.255.255.254204.255.255.25565,534

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.