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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.

Network217.2.0.0/16
Usable hosts65,534
Subnet mask255.255.0.0
Addresses65,536
Network address
217.2.0.0
Broadcast address
217.2.255.255
First usable
217.2.0.1
Last usable
217.2.255.254
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 D9020000 · Integer 3640786944 to 3640852479
Reverse DNS zone
2.217.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11011001.00000010..00000000.00000000217.2.0.0
Subnet mask11111111.11111111..00000000.00000000255.255.0.0
Network11011001.00000010..00000000.00000000217.2.0.0
Broadcast11011001.00000010..11111111.11111111217.2.255.255
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)

217.2.0.0/16 makes 256 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1217.2.0.0/24217.2.0.1 to 217.2.0.254217.2.0.255254
2217.2.1.0/24217.2.1.1 to 217.2.1.254217.2.1.255254
3217.2.2.0/24217.2.2.1 to 217.2.2.254217.2.2.255254
4217.2.3.0/24217.2.3.1 to 217.2.3.254217.2.3.255254
5217.2.4.0/24217.2.4.1 to 217.2.4.254217.2.4.255254
6217.2.5.0/24217.2.5.1 to 217.2.5.254217.2.5.255254
7217.2.6.0/24217.2.6.1 to 217.2.6.254217.2.6.255254
8217.2.7.0/24217.2.7.1 to 217.2.7.254217.2.7.255254
9217.2.8.0/24217.2.8.1 to 217.2.8.254217.2.8.255254
10217.2.9.0/24217.2.9.1 to 217.2.9.254217.2.9.255254
11217.2.10.0/24217.2.10.1 to 217.2.10.254217.2.10.255254
12217.2.11.0/24217.2.11.1 to 217.2.11.254217.2.11.255254
13217.2.12.0/24217.2.12.1 to 217.2.12.254217.2.12.255254
14217.2.13.0/24217.2.13.1 to 217.2.13.254217.2.13.255254
15217.2.14.0/24217.2.14.1 to 217.2.14.254217.2.14.255254
16217.2.15.0/24217.2.15.1 to 217.2.15.254217.2.15.255254
17217.2.16.0/24217.2.16.1 to 217.2.16.254217.2.16.255254
18217.2.17.0/24217.2.17.1 to 217.2.17.254217.2.17.255254
19217.2.18.0/24217.2.18.1 to 217.2.18.254217.2.18.255254
20217.2.19.0/24217.2.19.1 to 217.2.19.254217.2.19.255254
21217.2.20.0/24217.2.20.1 to 217.2.20.254217.2.20.255254
22217.2.21.0/24217.2.21.1 to 217.2.21.254217.2.21.255254
23217.2.22.0/24217.2.22.1 to 217.2.22.254217.2.22.255254
24217.2.23.0/24217.2.23.1 to 217.2.23.254217.2.23.255254
25217.2.24.0/24217.2.24.1 to 217.2.24.254217.2.24.255254
26217.2.25.0/24217.2.25.1 to 217.2.25.254217.2.25.255254
27217.2.26.0/24217.2.26.1 to 217.2.26.254217.2.26.255254
28217.2.27.0/24217.2.27.1 to 217.2.27.254217.2.27.255254
29217.2.28.0/24217.2.28.1 to 217.2.28.254217.2.28.255254
30217.2.29.0/24217.2.29.1 to 217.2.29.254217.2.29.255254
31217.2.30.0/24217.2.30.1 to 217.2.30.254217.2.30.255254
32217.2.31.0/24217.2.31.1 to 217.2.31.254217.2.31.255254
33217.2.32.0/24217.2.32.1 to 217.2.32.254217.2.32.255254
34217.2.33.0/24217.2.33.1 to 217.2.33.254217.2.33.255254
35217.2.34.0/24217.2.34.1 to 217.2.34.254217.2.34.255254
36217.2.35.0/24217.2.35.1 to 217.2.35.254217.2.35.255254
37217.2.36.0/24217.2.36.1 to 217.2.36.254217.2.36.255254
38217.2.37.0/24217.2.37.1 to 217.2.37.254217.2.37.255254
39217.2.38.0/24217.2.38.1 to 217.2.38.254217.2.38.255254
40217.2.39.0/24217.2.39.1 to 217.2.39.254217.2.39.255254
41217.2.40.0/24217.2.40.1 to 217.2.40.254217.2.40.255254
42217.2.41.0/24217.2.41.1 to 217.2.41.254217.2.41.255254
43217.2.42.0/24217.2.42.1 to 217.2.42.254217.2.42.255254
44217.2.43.0/24217.2.43.1 to 217.2.43.254217.2.43.255254
45217.2.44.0/24217.2.44.1 to 217.2.44.254217.2.44.255254
46217.2.45.0/24217.2.45.1 to 217.2.45.254217.2.45.255254
47217.2.46.0/24217.2.46.1 to 217.2.46.254217.2.46.255254
48217.2.47.0/24217.2.47.1 to 217.2.47.254217.2.47.255254
49217.2.48.0/24217.2.48.1 to 217.2.48.254217.2.48.255254
50217.2.49.0/24217.2.49.1 to 217.2.49.254217.2.49.255254
51217.2.50.0/24217.2.50.1 to 217.2.50.254217.2.50.255254
52217.2.51.0/24217.2.51.1 to 217.2.51.254217.2.51.255254
53217.2.52.0/24217.2.52.1 to 217.2.52.254217.2.52.255254
54217.2.53.0/24217.2.53.1 to 217.2.53.254217.2.53.255254
55217.2.54.0/24217.2.54.1 to 217.2.54.254217.2.54.255254
56217.2.55.0/24217.2.55.1 to 217.2.55.254217.2.55.255254
57217.2.56.0/24217.2.56.1 to 217.2.56.254217.2.56.255254
58217.2.57.0/24217.2.57.1 to 217.2.57.254217.2.57.255254
59217.2.58.0/24217.2.58.1 to 217.2.58.254217.2.58.255254
60217.2.59.0/24217.2.59.1 to 217.2.59.254217.2.59.255254
61217.2.60.0/24217.2.60.1 to 217.2.60.254217.2.60.255254
62217.2.61.0/24217.2.61.1 to 217.2.61.254217.2.61.255254
63217.2.62.0/24217.2.62.1 to 217.2.62.254217.2.62.255254
64217.2.63.0/24217.2.63.1 to 217.2.63.254217.2.63.255254
65217.2.64.0/24217.2.64.1 to 217.2.64.254217.2.64.255254
66217.2.65.0/24217.2.65.1 to 217.2.65.254217.2.65.255254
67217.2.66.0/24217.2.66.1 to 217.2.66.254217.2.66.255254
68217.2.67.0/24217.2.67.1 to 217.2.67.254217.2.67.255254
69217.2.68.0/24217.2.68.1 to 217.2.68.254217.2.68.255254
70217.2.69.0/24217.2.69.1 to 217.2.69.254217.2.69.255254
71217.2.70.0/24217.2.70.1 to 217.2.70.254217.2.70.255254
72217.2.71.0/24217.2.71.1 to 217.2.71.254217.2.71.255254
73217.2.72.0/24217.2.72.1 to 217.2.72.254217.2.72.255254
74217.2.73.0/24217.2.73.1 to 217.2.73.254217.2.73.255254
75217.2.74.0/24217.2.74.1 to 217.2.74.254217.2.74.255254
76217.2.75.0/24217.2.75.1 to 217.2.75.254217.2.75.255254
77217.2.76.0/24217.2.76.1 to 217.2.76.254217.2.76.255254
78217.2.77.0/24217.2.77.1 to 217.2.77.254217.2.77.255254
79217.2.78.0/24217.2.78.1 to 217.2.78.254217.2.78.255254
80217.2.79.0/24217.2.79.1 to 217.2.79.254217.2.79.255254
81217.2.80.0/24217.2.80.1 to 217.2.80.254217.2.80.255254
82217.2.81.0/24217.2.81.1 to 217.2.81.254217.2.81.255254
83217.2.82.0/24217.2.82.1 to 217.2.82.254217.2.82.255254
84217.2.83.0/24217.2.83.1 to 217.2.83.254217.2.83.255254
85217.2.84.0/24217.2.84.1 to 217.2.84.254217.2.84.255254
86217.2.85.0/24217.2.85.1 to 217.2.85.254217.2.85.255254
87217.2.86.0/24217.2.86.1 to 217.2.86.254217.2.86.255254
88217.2.87.0/24217.2.87.1 to 217.2.87.254217.2.87.255254
89217.2.88.0/24217.2.88.1 to 217.2.88.254217.2.88.255254
90217.2.89.0/24217.2.89.1 to 217.2.89.254217.2.89.255254
91217.2.90.0/24217.2.90.1 to 217.2.90.254217.2.90.255254
92217.2.91.0/24217.2.91.1 to 217.2.91.254217.2.91.255254
93217.2.92.0/24217.2.92.1 to 217.2.92.254217.2.92.255254
94217.2.93.0/24217.2.93.1 to 217.2.93.254217.2.93.255254
95217.2.94.0/24217.2.94.1 to 217.2.94.254217.2.94.255254
96217.2.95.0/24217.2.95.1 to 217.2.95.254217.2.95.255254
97217.2.96.0/24217.2.96.1 to 217.2.96.254217.2.96.255254
98217.2.97.0/24217.2.97.1 to 217.2.97.254217.2.97.255254
99217.2.98.0/24217.2.98.1 to 217.2.98.254217.2.98.255254
100217.2.99.0/24217.2.99.1 to 217.2.99.254217.2.99.255254
101217.2.100.0/24217.2.100.1 to 217.2.100.254217.2.100.255254
102217.2.101.0/24217.2.101.1 to 217.2.101.254217.2.101.255254
103217.2.102.0/24217.2.102.1 to 217.2.102.254217.2.102.255254
104217.2.103.0/24217.2.103.1 to 217.2.103.254217.2.103.255254
105217.2.104.0/24217.2.104.1 to 217.2.104.254217.2.104.255254
106217.2.105.0/24217.2.105.1 to 217.2.105.254217.2.105.255254
107217.2.106.0/24217.2.106.1 to 217.2.106.254217.2.106.255254
108217.2.107.0/24217.2.107.1 to 217.2.107.254217.2.107.255254
109217.2.108.0/24217.2.108.1 to 217.2.108.254217.2.108.255254
110217.2.109.0/24217.2.109.1 to 217.2.109.254217.2.109.255254
111217.2.110.0/24217.2.110.1 to 217.2.110.254217.2.110.255254
112217.2.111.0/24217.2.111.1 to 217.2.111.254217.2.111.255254
113217.2.112.0/24217.2.112.1 to 217.2.112.254217.2.112.255254
114217.2.113.0/24217.2.113.1 to 217.2.113.254217.2.113.255254
115217.2.114.0/24217.2.114.1 to 217.2.114.254217.2.114.255254
116217.2.115.0/24217.2.115.1 to 217.2.115.254217.2.115.255254
117217.2.116.0/24217.2.116.1 to 217.2.116.254217.2.116.255254
118217.2.117.0/24217.2.117.1 to 217.2.117.254217.2.117.255254
119217.2.118.0/24217.2.118.1 to 217.2.118.254217.2.118.255254
120217.2.119.0/24217.2.119.1 to 217.2.119.254217.2.119.255254
121217.2.120.0/24217.2.120.1 to 217.2.120.254217.2.120.255254
122217.2.121.0/24217.2.121.1 to 217.2.121.254217.2.121.255254
123217.2.122.0/24217.2.122.1 to 217.2.122.254217.2.122.255254
124217.2.123.0/24217.2.123.1 to 217.2.123.254217.2.123.255254
125217.2.124.0/24217.2.124.1 to 217.2.124.254217.2.124.255254
126217.2.125.0/24217.2.125.1 to 217.2.125.254217.2.125.255254
127217.2.126.0/24217.2.126.1 to 217.2.126.254217.2.126.255254
128217.2.127.0/24217.2.127.1 to 217.2.127.254217.2.127.255254
129217.2.128.0/24217.2.128.1 to 217.2.128.254217.2.128.255254
130217.2.129.0/24217.2.129.1 to 217.2.129.254217.2.129.255254
131217.2.130.0/24217.2.130.1 to 217.2.130.254217.2.130.255254
132217.2.131.0/24217.2.131.1 to 217.2.131.254217.2.131.255254
133217.2.132.0/24217.2.132.1 to 217.2.132.254217.2.132.255254
134217.2.133.0/24217.2.133.1 to 217.2.133.254217.2.133.255254
135217.2.134.0/24217.2.134.1 to 217.2.134.254217.2.134.255254
136217.2.135.0/24217.2.135.1 to 217.2.135.254217.2.135.255254
137217.2.136.0/24217.2.136.1 to 217.2.136.254217.2.136.255254
138217.2.137.0/24217.2.137.1 to 217.2.137.254217.2.137.255254
139217.2.138.0/24217.2.138.1 to 217.2.138.254217.2.138.255254
140217.2.139.0/24217.2.139.1 to 217.2.139.254217.2.139.255254
141217.2.140.0/24217.2.140.1 to 217.2.140.254217.2.140.255254
142217.2.141.0/24217.2.141.1 to 217.2.141.254217.2.141.255254
143217.2.142.0/24217.2.142.1 to 217.2.142.254217.2.142.255254
144217.2.143.0/24217.2.143.1 to 217.2.143.254217.2.143.255254
145217.2.144.0/24217.2.144.1 to 217.2.144.254217.2.144.255254
146217.2.145.0/24217.2.145.1 to 217.2.145.254217.2.145.255254
147217.2.146.0/24217.2.146.1 to 217.2.146.254217.2.146.255254
148217.2.147.0/24217.2.147.1 to 217.2.147.254217.2.147.255254
149217.2.148.0/24217.2.148.1 to 217.2.148.254217.2.148.255254
150217.2.149.0/24217.2.149.1 to 217.2.149.254217.2.149.255254
151217.2.150.0/24217.2.150.1 to 217.2.150.254217.2.150.255254
152217.2.151.0/24217.2.151.1 to 217.2.151.254217.2.151.255254
153217.2.152.0/24217.2.152.1 to 217.2.152.254217.2.152.255254
154217.2.153.0/24217.2.153.1 to 217.2.153.254217.2.153.255254
155217.2.154.0/24217.2.154.1 to 217.2.154.254217.2.154.255254
156217.2.155.0/24217.2.155.1 to 217.2.155.254217.2.155.255254
157217.2.156.0/24217.2.156.1 to 217.2.156.254217.2.156.255254
158217.2.157.0/24217.2.157.1 to 217.2.157.254217.2.157.255254
159217.2.158.0/24217.2.158.1 to 217.2.158.254217.2.158.255254
160217.2.159.0/24217.2.159.1 to 217.2.159.254217.2.159.255254
161217.2.160.0/24217.2.160.1 to 217.2.160.254217.2.160.255254
162217.2.161.0/24217.2.161.1 to 217.2.161.254217.2.161.255254
163217.2.162.0/24217.2.162.1 to 217.2.162.254217.2.162.255254
164217.2.163.0/24217.2.163.1 to 217.2.163.254217.2.163.255254
165217.2.164.0/24217.2.164.1 to 217.2.164.254217.2.164.255254
166217.2.165.0/24217.2.165.1 to 217.2.165.254217.2.165.255254
167217.2.166.0/24217.2.166.1 to 217.2.166.254217.2.166.255254
168217.2.167.0/24217.2.167.1 to 217.2.167.254217.2.167.255254
169217.2.168.0/24217.2.168.1 to 217.2.168.254217.2.168.255254
170217.2.169.0/24217.2.169.1 to 217.2.169.254217.2.169.255254
171217.2.170.0/24217.2.170.1 to 217.2.170.254217.2.170.255254
172217.2.171.0/24217.2.171.1 to 217.2.171.254217.2.171.255254
173217.2.172.0/24217.2.172.1 to 217.2.172.254217.2.172.255254
174217.2.173.0/24217.2.173.1 to 217.2.173.254217.2.173.255254
175217.2.174.0/24217.2.174.1 to 217.2.174.254217.2.174.255254
176217.2.175.0/24217.2.175.1 to 217.2.175.254217.2.175.255254
177217.2.176.0/24217.2.176.1 to 217.2.176.254217.2.176.255254
178217.2.177.0/24217.2.177.1 to 217.2.177.254217.2.177.255254
179217.2.178.0/24217.2.178.1 to 217.2.178.254217.2.178.255254
180217.2.179.0/24217.2.179.1 to 217.2.179.254217.2.179.255254
181217.2.180.0/24217.2.180.1 to 217.2.180.254217.2.180.255254
182217.2.181.0/24217.2.181.1 to 217.2.181.254217.2.181.255254
183217.2.182.0/24217.2.182.1 to 217.2.182.254217.2.182.255254
184217.2.183.0/24217.2.183.1 to 217.2.183.254217.2.183.255254
185217.2.184.0/24217.2.184.1 to 217.2.184.254217.2.184.255254
186217.2.185.0/24217.2.185.1 to 217.2.185.254217.2.185.255254
187217.2.186.0/24217.2.186.1 to 217.2.186.254217.2.186.255254
188217.2.187.0/24217.2.187.1 to 217.2.187.254217.2.187.255254
189217.2.188.0/24217.2.188.1 to 217.2.188.254217.2.188.255254
190217.2.189.0/24217.2.189.1 to 217.2.189.254217.2.189.255254
191217.2.190.0/24217.2.190.1 to 217.2.190.254217.2.190.255254
192217.2.191.0/24217.2.191.1 to 217.2.191.254217.2.191.255254
193217.2.192.0/24217.2.192.1 to 217.2.192.254217.2.192.255254
194217.2.193.0/24217.2.193.1 to 217.2.193.254217.2.193.255254
195217.2.194.0/24217.2.194.1 to 217.2.194.254217.2.194.255254
196217.2.195.0/24217.2.195.1 to 217.2.195.254217.2.195.255254
197217.2.196.0/24217.2.196.1 to 217.2.196.254217.2.196.255254
198217.2.197.0/24217.2.197.1 to 217.2.197.254217.2.197.255254
199217.2.198.0/24217.2.198.1 to 217.2.198.254217.2.198.255254
200217.2.199.0/24217.2.199.1 to 217.2.199.254217.2.199.255254
201217.2.200.0/24217.2.200.1 to 217.2.200.254217.2.200.255254
202217.2.201.0/24217.2.201.1 to 217.2.201.254217.2.201.255254
203217.2.202.0/24217.2.202.1 to 217.2.202.254217.2.202.255254
204217.2.203.0/24217.2.203.1 to 217.2.203.254217.2.203.255254
205217.2.204.0/24217.2.204.1 to 217.2.204.254217.2.204.255254
206217.2.205.0/24217.2.205.1 to 217.2.205.254217.2.205.255254
207217.2.206.0/24217.2.206.1 to 217.2.206.254217.2.206.255254
208217.2.207.0/24217.2.207.1 to 217.2.207.254217.2.207.255254
209217.2.208.0/24217.2.208.1 to 217.2.208.254217.2.208.255254
210217.2.209.0/24217.2.209.1 to 217.2.209.254217.2.209.255254
211217.2.210.0/24217.2.210.1 to 217.2.210.254217.2.210.255254
212217.2.211.0/24217.2.211.1 to 217.2.211.254217.2.211.255254
213217.2.212.0/24217.2.212.1 to 217.2.212.254217.2.212.255254
214217.2.213.0/24217.2.213.1 to 217.2.213.254217.2.213.255254
215217.2.214.0/24217.2.214.1 to 217.2.214.254217.2.214.255254
216217.2.215.0/24217.2.215.1 to 217.2.215.254217.2.215.255254
217217.2.216.0/24217.2.216.1 to 217.2.216.254217.2.216.255254
218217.2.217.0/24217.2.217.1 to 217.2.217.254217.2.217.255254
219217.2.218.0/24217.2.218.1 to 217.2.218.254217.2.218.255254
220217.2.219.0/24217.2.219.1 to 217.2.219.254217.2.219.255254
221217.2.220.0/24217.2.220.1 to 217.2.220.254217.2.220.255254
222217.2.221.0/24217.2.221.1 to 217.2.221.254217.2.221.255254
223217.2.222.0/24217.2.222.1 to 217.2.222.254217.2.222.255254
224217.2.223.0/24217.2.223.1 to 217.2.223.254217.2.223.255254
225217.2.224.0/24217.2.224.1 to 217.2.224.254217.2.224.255254
226217.2.225.0/24217.2.225.1 to 217.2.225.254217.2.225.255254
227217.2.226.0/24217.2.226.1 to 217.2.226.254217.2.226.255254
228217.2.227.0/24217.2.227.1 to 217.2.227.254217.2.227.255254
229217.2.228.0/24217.2.228.1 to 217.2.228.254217.2.228.255254
230217.2.229.0/24217.2.229.1 to 217.2.229.254217.2.229.255254
231217.2.230.0/24217.2.230.1 to 217.2.230.254217.2.230.255254
232217.2.231.0/24217.2.231.1 to 217.2.231.254217.2.231.255254
233217.2.232.0/24217.2.232.1 to 217.2.232.254217.2.232.255254
234217.2.233.0/24217.2.233.1 to 217.2.233.254217.2.233.255254
235217.2.234.0/24217.2.234.1 to 217.2.234.254217.2.234.255254
236217.2.235.0/24217.2.235.1 to 217.2.235.254217.2.235.255254
237217.2.236.0/24217.2.236.1 to 217.2.236.254217.2.236.255254
238217.2.237.0/24217.2.237.1 to 217.2.237.254217.2.237.255254
239217.2.238.0/24217.2.238.1 to 217.2.238.254217.2.238.255254
240217.2.239.0/24217.2.239.1 to 217.2.239.254217.2.239.255254
241217.2.240.0/24217.2.240.1 to 217.2.240.254217.2.240.255254
242217.2.241.0/24217.2.241.1 to 217.2.241.254217.2.241.255254
243217.2.242.0/24217.2.242.1 to 217.2.242.254217.2.242.255254
244217.2.243.0/24217.2.243.1 to 217.2.243.254217.2.243.255254
245217.2.244.0/24217.2.244.1 to 217.2.244.254217.2.244.255254
246217.2.245.0/24217.2.245.1 to 217.2.245.254217.2.245.255254
247217.2.246.0/24217.2.246.1 to 217.2.246.254217.2.246.255254
248217.2.247.0/24217.2.247.1 to 217.2.247.254217.2.247.255254
249217.2.248.0/24217.2.248.1 to 217.2.248.254217.2.248.255254
250217.2.249.0/24217.2.249.1 to 217.2.249.254217.2.249.255254
251217.2.250.0/24217.2.250.1 to 217.2.250.254217.2.250.255254
252217.2.251.0/24217.2.251.1 to 217.2.251.254217.2.251.255254
253217.2.252.0/24217.2.252.1 to 217.2.252.254217.2.252.255254
254217.2.253.0/24217.2.253.1 to 217.2.253.254217.2.253.255254
255217.2.254.0/24217.2.254.1 to 217.2.254.254217.2.254.255254
256217.2.255.0/24217.2.255.1 to 217.2.255.254217.2.255.255254

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.