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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.

Network210.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
210.0.0.0
Broadcast address
211.255.255.255
First usable
210.0.0.1
Last usable
211.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
C (default /24)
As numbers
Hex D2000000 · Integer 3523215360 to 3556769791
Reverse DNS zones
210.in-addr.arpa
211.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11010010.00000000.00000000.00000000210.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network11010010.00000000.00000000.00000000210.0.0.0
Broadcast11010011.11111111.11111111.11111111211.255.255.255
Split into smaller subnets/14
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

210.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1210.0.0.0/14210.0.0.1 to 210.3.255.254210.3.255.255262,142
2210.4.0.0/14210.4.0.1 to 210.7.255.254210.7.255.255262,142
3210.8.0.0/14210.8.0.1 to 210.11.255.254210.11.255.255262,142
4210.12.0.0/14210.12.0.1 to 210.15.255.254210.15.255.255262,142
5210.16.0.0/14210.16.0.1 to 210.19.255.254210.19.255.255262,142
6210.20.0.0/14210.20.0.1 to 210.23.255.254210.23.255.255262,142
7210.24.0.0/14210.24.0.1 to 210.27.255.254210.27.255.255262,142
8210.28.0.0/14210.28.0.1 to 210.31.255.254210.31.255.255262,142
9210.32.0.0/14210.32.0.1 to 210.35.255.254210.35.255.255262,142
10210.36.0.0/14210.36.0.1 to 210.39.255.254210.39.255.255262,142
11210.40.0.0/14210.40.0.1 to 210.43.255.254210.43.255.255262,142
12210.44.0.0/14210.44.0.1 to 210.47.255.254210.47.255.255262,142
13210.48.0.0/14210.48.0.1 to 210.51.255.254210.51.255.255262,142
14210.52.0.0/14210.52.0.1 to 210.55.255.254210.55.255.255262,142
15210.56.0.0/14210.56.0.1 to 210.59.255.254210.59.255.255262,142
16210.60.0.0/14210.60.0.1 to 210.63.255.254210.63.255.255262,142
17210.64.0.0/14210.64.0.1 to 210.67.255.254210.67.255.255262,142
18210.68.0.0/14210.68.0.1 to 210.71.255.254210.71.255.255262,142
19210.72.0.0/14210.72.0.1 to 210.75.255.254210.75.255.255262,142
20210.76.0.0/14210.76.0.1 to 210.79.255.254210.79.255.255262,142
21210.80.0.0/14210.80.0.1 to 210.83.255.254210.83.255.255262,142
22210.84.0.0/14210.84.0.1 to 210.87.255.254210.87.255.255262,142
23210.88.0.0/14210.88.0.1 to 210.91.255.254210.91.255.255262,142
24210.92.0.0/14210.92.0.1 to 210.95.255.254210.95.255.255262,142
25210.96.0.0/14210.96.0.1 to 210.99.255.254210.99.255.255262,142
26210.100.0.0/14210.100.0.1 to 210.103.255.254210.103.255.255262,142
27210.104.0.0/14210.104.0.1 to 210.107.255.254210.107.255.255262,142
28210.108.0.0/14210.108.0.1 to 210.111.255.254210.111.255.255262,142
29210.112.0.0/14210.112.0.1 to 210.115.255.254210.115.255.255262,142
30210.116.0.0/14210.116.0.1 to 210.119.255.254210.119.255.255262,142
31210.120.0.0/14210.120.0.1 to 210.123.255.254210.123.255.255262,142
32210.124.0.0/14210.124.0.1 to 210.127.255.254210.127.255.255262,142
33210.128.0.0/14210.128.0.1 to 210.131.255.254210.131.255.255262,142
34210.132.0.0/14210.132.0.1 to 210.135.255.254210.135.255.255262,142
35210.136.0.0/14210.136.0.1 to 210.139.255.254210.139.255.255262,142
36210.140.0.0/14210.140.0.1 to 210.143.255.254210.143.255.255262,142
37210.144.0.0/14210.144.0.1 to 210.147.255.254210.147.255.255262,142
38210.148.0.0/14210.148.0.1 to 210.151.255.254210.151.255.255262,142
39210.152.0.0/14210.152.0.1 to 210.155.255.254210.155.255.255262,142
40210.156.0.0/14210.156.0.1 to 210.159.255.254210.159.255.255262,142
41210.160.0.0/14210.160.0.1 to 210.163.255.254210.163.255.255262,142
42210.164.0.0/14210.164.0.1 to 210.167.255.254210.167.255.255262,142
43210.168.0.0/14210.168.0.1 to 210.171.255.254210.171.255.255262,142
44210.172.0.0/14210.172.0.1 to 210.175.255.254210.175.255.255262,142
45210.176.0.0/14210.176.0.1 to 210.179.255.254210.179.255.255262,142
46210.180.0.0/14210.180.0.1 to 210.183.255.254210.183.255.255262,142
47210.184.0.0/14210.184.0.1 to 210.187.255.254210.187.255.255262,142
48210.188.0.0/14210.188.0.1 to 210.191.255.254210.191.255.255262,142
49210.192.0.0/14210.192.0.1 to 210.195.255.254210.195.255.255262,142
50210.196.0.0/14210.196.0.1 to 210.199.255.254210.199.255.255262,142
51210.200.0.0/14210.200.0.1 to 210.203.255.254210.203.255.255262,142
52210.204.0.0/14210.204.0.1 to 210.207.255.254210.207.255.255262,142
53210.208.0.0/14210.208.0.1 to 210.211.255.254210.211.255.255262,142
54210.212.0.0/14210.212.0.1 to 210.215.255.254210.215.255.255262,142
55210.216.0.0/14210.216.0.1 to 210.219.255.254210.219.255.255262,142
56210.220.0.0/14210.220.0.1 to 210.223.255.254210.223.255.255262,142
57210.224.0.0/14210.224.0.1 to 210.227.255.254210.227.255.255262,142
58210.228.0.0/14210.228.0.1 to 210.231.255.254210.231.255.255262,142
59210.232.0.0/14210.232.0.1 to 210.235.255.254210.235.255.255262,142
60210.236.0.0/14210.236.0.1 to 210.239.255.254210.239.255.255262,142
61210.240.0.0/14210.240.0.1 to 210.243.255.254210.243.255.255262,142
62210.244.0.0/14210.244.0.1 to 210.247.255.254210.247.255.255262,142
63210.248.0.0/14210.248.0.1 to 210.251.255.254210.251.255.255262,142
64210.252.0.0/14210.252.0.1 to 210.255.255.254210.255.255.255262,142
65211.0.0.0/14211.0.0.1 to 211.3.255.254211.3.255.255262,142
66211.4.0.0/14211.4.0.1 to 211.7.255.254211.7.255.255262,142
67211.8.0.0/14211.8.0.1 to 211.11.255.254211.11.255.255262,142
68211.12.0.0/14211.12.0.1 to 211.15.255.254211.15.255.255262,142
69211.16.0.0/14211.16.0.1 to 211.19.255.254211.19.255.255262,142
70211.20.0.0/14211.20.0.1 to 211.23.255.254211.23.255.255262,142
71211.24.0.0/14211.24.0.1 to 211.27.255.254211.27.255.255262,142
72211.28.0.0/14211.28.0.1 to 211.31.255.254211.31.255.255262,142
73211.32.0.0/14211.32.0.1 to 211.35.255.254211.35.255.255262,142
74211.36.0.0/14211.36.0.1 to 211.39.255.254211.39.255.255262,142
75211.40.0.0/14211.40.0.1 to 211.43.255.254211.43.255.255262,142
76211.44.0.0/14211.44.0.1 to 211.47.255.254211.47.255.255262,142
77211.48.0.0/14211.48.0.1 to 211.51.255.254211.51.255.255262,142
78211.52.0.0/14211.52.0.1 to 211.55.255.254211.55.255.255262,142
79211.56.0.0/14211.56.0.1 to 211.59.255.254211.59.255.255262,142
80211.60.0.0/14211.60.0.1 to 211.63.255.254211.63.255.255262,142
81211.64.0.0/14211.64.0.1 to 211.67.255.254211.67.255.255262,142
82211.68.0.0/14211.68.0.1 to 211.71.255.254211.71.255.255262,142
83211.72.0.0/14211.72.0.1 to 211.75.255.254211.75.255.255262,142
84211.76.0.0/14211.76.0.1 to 211.79.255.254211.79.255.255262,142
85211.80.0.0/14211.80.0.1 to 211.83.255.254211.83.255.255262,142
86211.84.0.0/14211.84.0.1 to 211.87.255.254211.87.255.255262,142
87211.88.0.0/14211.88.0.1 to 211.91.255.254211.91.255.255262,142
88211.92.0.0/14211.92.0.1 to 211.95.255.254211.95.255.255262,142
89211.96.0.0/14211.96.0.1 to 211.99.255.254211.99.255.255262,142
90211.100.0.0/14211.100.0.1 to 211.103.255.254211.103.255.255262,142
91211.104.0.0/14211.104.0.1 to 211.107.255.254211.107.255.255262,142
92211.108.0.0/14211.108.0.1 to 211.111.255.254211.111.255.255262,142
93211.112.0.0/14211.112.0.1 to 211.115.255.254211.115.255.255262,142
94211.116.0.0/14211.116.0.1 to 211.119.255.254211.119.255.255262,142
95211.120.0.0/14211.120.0.1 to 211.123.255.254211.123.255.255262,142
96211.124.0.0/14211.124.0.1 to 211.127.255.254211.127.255.255262,142
97211.128.0.0/14211.128.0.1 to 211.131.255.254211.131.255.255262,142
98211.132.0.0/14211.132.0.1 to 211.135.255.254211.135.255.255262,142
99211.136.0.0/14211.136.0.1 to 211.139.255.254211.139.255.255262,142
100211.140.0.0/14211.140.0.1 to 211.143.255.254211.143.255.255262,142
101211.144.0.0/14211.144.0.1 to 211.147.255.254211.147.255.255262,142
102211.148.0.0/14211.148.0.1 to 211.151.255.254211.151.255.255262,142
103211.152.0.0/14211.152.0.1 to 211.155.255.254211.155.255.255262,142
104211.156.0.0/14211.156.0.1 to 211.159.255.254211.159.255.255262,142
105211.160.0.0/14211.160.0.1 to 211.163.255.254211.163.255.255262,142
106211.164.0.0/14211.164.0.1 to 211.167.255.254211.167.255.255262,142
107211.168.0.0/14211.168.0.1 to 211.171.255.254211.171.255.255262,142
108211.172.0.0/14211.172.0.1 to 211.175.255.254211.175.255.255262,142
109211.176.0.0/14211.176.0.1 to 211.179.255.254211.179.255.255262,142
110211.180.0.0/14211.180.0.1 to 211.183.255.254211.183.255.255262,142
111211.184.0.0/14211.184.0.1 to 211.187.255.254211.187.255.255262,142
112211.188.0.0/14211.188.0.1 to 211.191.255.254211.191.255.255262,142
113211.192.0.0/14211.192.0.1 to 211.195.255.254211.195.255.255262,142
114211.196.0.0/14211.196.0.1 to 211.199.255.254211.199.255.255262,142
115211.200.0.0/14211.200.0.1 to 211.203.255.254211.203.255.255262,142
116211.204.0.0/14211.204.0.1 to 211.207.255.254211.207.255.255262,142
117211.208.0.0/14211.208.0.1 to 211.211.255.254211.211.255.255262,142
118211.212.0.0/14211.212.0.1 to 211.215.255.254211.215.255.255262,142
119211.216.0.0/14211.216.0.1 to 211.219.255.254211.219.255.255262,142
120211.220.0.0/14211.220.0.1 to 211.223.255.254211.223.255.255262,142
121211.224.0.0/14211.224.0.1 to 211.227.255.254211.227.255.255262,142
122211.228.0.0/14211.228.0.1 to 211.231.255.254211.231.255.255262,142
123211.232.0.0/14211.232.0.1 to 211.235.255.254211.235.255.255262,142
124211.236.0.0/14211.236.0.1 to 211.239.255.254211.239.255.255262,142
125211.240.0.0/14211.240.0.1 to 211.243.255.254211.243.255.255262,142
126211.244.0.0/14211.244.0.1 to 211.247.255.254211.247.255.255262,142
127211.248.0.0/14211.248.0.1 to 211.251.255.254211.251.255.255262,142
128211.252.0.0/14211.252.0.1 to 211.255.255.254211.255.255.255262,142

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.