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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.

Network1.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
1.0.0.0
Broadcast address
1.63.255.255
First usable
1.0.0.1
Last usable
1.63.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Public public
Old class
A (default /8)
As numbers
Hex 01000000 · Integer 16777216 to 20971519
Reverse DNS zones
0.1.in-addr.arpa
1.1.in-addr.arpa
2.1.in-addr.arpa
3.1.in-addr.arpa
4.1.in-addr.arpa
5.1.in-addr.arpa
6.1.in-addr.arpa
7.1.in-addr.arpa
8.1.in-addr.arpa
9.1.in-addr.arpa
10.1.in-addr.arpa
11.1.in-addr.arpa
12.1.in-addr.arpa
13.1.in-addr.arpa
14.1.in-addr.arpa
15.1.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00000001.00000000.00000000.000000001.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network00000001.00000000.00000000.000000001.0.0.0
Broadcast00000001.00111111.11111111.111111111.63.255.255
Split into smaller subnets/17
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

1.0.0.0/10 makes 128 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
11.0.0.0/171.0.0.1 to 1.0.127.2541.0.127.25532,766
21.0.128.0/171.0.128.1 to 1.0.255.2541.0.255.25532,766
31.1.0.0/171.1.0.1 to 1.1.127.2541.1.127.25532,766
41.1.128.0/171.1.128.1 to 1.1.255.2541.1.255.25532,766
51.2.0.0/171.2.0.1 to 1.2.127.2541.2.127.25532,766
61.2.128.0/171.2.128.1 to 1.2.255.2541.2.255.25532,766
71.3.0.0/171.3.0.1 to 1.3.127.2541.3.127.25532,766
81.3.128.0/171.3.128.1 to 1.3.255.2541.3.255.25532,766
91.4.0.0/171.4.0.1 to 1.4.127.2541.4.127.25532,766
101.4.128.0/171.4.128.1 to 1.4.255.2541.4.255.25532,766
111.5.0.0/171.5.0.1 to 1.5.127.2541.5.127.25532,766
121.5.128.0/171.5.128.1 to 1.5.255.2541.5.255.25532,766
131.6.0.0/171.6.0.1 to 1.6.127.2541.6.127.25532,766
141.6.128.0/171.6.128.1 to 1.6.255.2541.6.255.25532,766
151.7.0.0/171.7.0.1 to 1.7.127.2541.7.127.25532,766
161.7.128.0/171.7.128.1 to 1.7.255.2541.7.255.25532,766
171.8.0.0/171.8.0.1 to 1.8.127.2541.8.127.25532,766
181.8.128.0/171.8.128.1 to 1.8.255.2541.8.255.25532,766
191.9.0.0/171.9.0.1 to 1.9.127.2541.9.127.25532,766
201.9.128.0/171.9.128.1 to 1.9.255.2541.9.255.25532,766
211.10.0.0/171.10.0.1 to 1.10.127.2541.10.127.25532,766
221.10.128.0/171.10.128.1 to 1.10.255.2541.10.255.25532,766
231.11.0.0/171.11.0.1 to 1.11.127.2541.11.127.25532,766
241.11.128.0/171.11.128.1 to 1.11.255.2541.11.255.25532,766
251.12.0.0/171.12.0.1 to 1.12.127.2541.12.127.25532,766
261.12.128.0/171.12.128.1 to 1.12.255.2541.12.255.25532,766
271.13.0.0/171.13.0.1 to 1.13.127.2541.13.127.25532,766
281.13.128.0/171.13.128.1 to 1.13.255.2541.13.255.25532,766
291.14.0.0/171.14.0.1 to 1.14.127.2541.14.127.25532,766
301.14.128.0/171.14.128.1 to 1.14.255.2541.14.255.25532,766
311.15.0.0/171.15.0.1 to 1.15.127.2541.15.127.25532,766
321.15.128.0/171.15.128.1 to 1.15.255.2541.15.255.25532,766
331.16.0.0/171.16.0.1 to 1.16.127.2541.16.127.25532,766
341.16.128.0/171.16.128.1 to 1.16.255.2541.16.255.25532,766
351.17.0.0/171.17.0.1 to 1.17.127.2541.17.127.25532,766
361.17.128.0/171.17.128.1 to 1.17.255.2541.17.255.25532,766
371.18.0.0/171.18.0.1 to 1.18.127.2541.18.127.25532,766
381.18.128.0/171.18.128.1 to 1.18.255.2541.18.255.25532,766
391.19.0.0/171.19.0.1 to 1.19.127.2541.19.127.25532,766
401.19.128.0/171.19.128.1 to 1.19.255.2541.19.255.25532,766
411.20.0.0/171.20.0.1 to 1.20.127.2541.20.127.25532,766
421.20.128.0/171.20.128.1 to 1.20.255.2541.20.255.25532,766
431.21.0.0/171.21.0.1 to 1.21.127.2541.21.127.25532,766
441.21.128.0/171.21.128.1 to 1.21.255.2541.21.255.25532,766
451.22.0.0/171.22.0.1 to 1.22.127.2541.22.127.25532,766
461.22.128.0/171.22.128.1 to 1.22.255.2541.22.255.25532,766
471.23.0.0/171.23.0.1 to 1.23.127.2541.23.127.25532,766
481.23.128.0/171.23.128.1 to 1.23.255.2541.23.255.25532,766
491.24.0.0/171.24.0.1 to 1.24.127.2541.24.127.25532,766
501.24.128.0/171.24.128.1 to 1.24.255.2541.24.255.25532,766
511.25.0.0/171.25.0.1 to 1.25.127.2541.25.127.25532,766
521.25.128.0/171.25.128.1 to 1.25.255.2541.25.255.25532,766
531.26.0.0/171.26.0.1 to 1.26.127.2541.26.127.25532,766
541.26.128.0/171.26.128.1 to 1.26.255.2541.26.255.25532,766
551.27.0.0/171.27.0.1 to 1.27.127.2541.27.127.25532,766
561.27.128.0/171.27.128.1 to 1.27.255.2541.27.255.25532,766
571.28.0.0/171.28.0.1 to 1.28.127.2541.28.127.25532,766
581.28.128.0/171.28.128.1 to 1.28.255.2541.28.255.25532,766
591.29.0.0/171.29.0.1 to 1.29.127.2541.29.127.25532,766
601.29.128.0/171.29.128.1 to 1.29.255.2541.29.255.25532,766
611.30.0.0/171.30.0.1 to 1.30.127.2541.30.127.25532,766
621.30.128.0/171.30.128.1 to 1.30.255.2541.30.255.25532,766
631.31.0.0/171.31.0.1 to 1.31.127.2541.31.127.25532,766
641.31.128.0/171.31.128.1 to 1.31.255.2541.31.255.25532,766
651.32.0.0/171.32.0.1 to 1.32.127.2541.32.127.25532,766
661.32.128.0/171.32.128.1 to 1.32.255.2541.32.255.25532,766
671.33.0.0/171.33.0.1 to 1.33.127.2541.33.127.25532,766
681.33.128.0/171.33.128.1 to 1.33.255.2541.33.255.25532,766
691.34.0.0/171.34.0.1 to 1.34.127.2541.34.127.25532,766
701.34.128.0/171.34.128.1 to 1.34.255.2541.34.255.25532,766
711.35.0.0/171.35.0.1 to 1.35.127.2541.35.127.25532,766
721.35.128.0/171.35.128.1 to 1.35.255.2541.35.255.25532,766
731.36.0.0/171.36.0.1 to 1.36.127.2541.36.127.25532,766
741.36.128.0/171.36.128.1 to 1.36.255.2541.36.255.25532,766
751.37.0.0/171.37.0.1 to 1.37.127.2541.37.127.25532,766
761.37.128.0/171.37.128.1 to 1.37.255.2541.37.255.25532,766
771.38.0.0/171.38.0.1 to 1.38.127.2541.38.127.25532,766
781.38.128.0/171.38.128.1 to 1.38.255.2541.38.255.25532,766
791.39.0.0/171.39.0.1 to 1.39.127.2541.39.127.25532,766
801.39.128.0/171.39.128.1 to 1.39.255.2541.39.255.25532,766
811.40.0.0/171.40.0.1 to 1.40.127.2541.40.127.25532,766
821.40.128.0/171.40.128.1 to 1.40.255.2541.40.255.25532,766
831.41.0.0/171.41.0.1 to 1.41.127.2541.41.127.25532,766
841.41.128.0/171.41.128.1 to 1.41.255.2541.41.255.25532,766
851.42.0.0/171.42.0.1 to 1.42.127.2541.42.127.25532,766
861.42.128.0/171.42.128.1 to 1.42.255.2541.42.255.25532,766
871.43.0.0/171.43.0.1 to 1.43.127.2541.43.127.25532,766
881.43.128.0/171.43.128.1 to 1.43.255.2541.43.255.25532,766
891.44.0.0/171.44.0.1 to 1.44.127.2541.44.127.25532,766
901.44.128.0/171.44.128.1 to 1.44.255.2541.44.255.25532,766
911.45.0.0/171.45.0.1 to 1.45.127.2541.45.127.25532,766
921.45.128.0/171.45.128.1 to 1.45.255.2541.45.255.25532,766
931.46.0.0/171.46.0.1 to 1.46.127.2541.46.127.25532,766
941.46.128.0/171.46.128.1 to 1.46.255.2541.46.255.25532,766
951.47.0.0/171.47.0.1 to 1.47.127.2541.47.127.25532,766
961.47.128.0/171.47.128.1 to 1.47.255.2541.47.255.25532,766
971.48.0.0/171.48.0.1 to 1.48.127.2541.48.127.25532,766
981.48.128.0/171.48.128.1 to 1.48.255.2541.48.255.25532,766
991.49.0.0/171.49.0.1 to 1.49.127.2541.49.127.25532,766
1001.49.128.0/171.49.128.1 to 1.49.255.2541.49.255.25532,766
1011.50.0.0/171.50.0.1 to 1.50.127.2541.50.127.25532,766
1021.50.128.0/171.50.128.1 to 1.50.255.2541.50.255.25532,766
1031.51.0.0/171.51.0.1 to 1.51.127.2541.51.127.25532,766
1041.51.128.0/171.51.128.1 to 1.51.255.2541.51.255.25532,766
1051.52.0.0/171.52.0.1 to 1.52.127.2541.52.127.25532,766
1061.52.128.0/171.52.128.1 to 1.52.255.2541.52.255.25532,766
1071.53.0.0/171.53.0.1 to 1.53.127.2541.53.127.25532,766
1081.53.128.0/171.53.128.1 to 1.53.255.2541.53.255.25532,766
1091.54.0.0/171.54.0.1 to 1.54.127.2541.54.127.25532,766
1101.54.128.0/171.54.128.1 to 1.54.255.2541.54.255.25532,766
1111.55.0.0/171.55.0.1 to 1.55.127.2541.55.127.25532,766
1121.55.128.0/171.55.128.1 to 1.55.255.2541.55.255.25532,766
1131.56.0.0/171.56.0.1 to 1.56.127.2541.56.127.25532,766
1141.56.128.0/171.56.128.1 to 1.56.255.2541.56.255.25532,766
1151.57.0.0/171.57.0.1 to 1.57.127.2541.57.127.25532,766
1161.57.128.0/171.57.128.1 to 1.57.255.2541.57.255.25532,766
1171.58.0.0/171.58.0.1 to 1.58.127.2541.58.127.25532,766
1181.58.128.0/171.58.128.1 to 1.58.255.2541.58.255.25532,766
1191.59.0.0/171.59.0.1 to 1.59.127.2541.59.127.25532,766
1201.59.128.0/171.59.128.1 to 1.59.255.2541.59.255.25532,766
1211.60.0.0/171.60.0.1 to 1.60.127.2541.60.127.25532,766
1221.60.128.0/171.60.128.1 to 1.60.255.2541.60.255.25532,766
1231.61.0.0/171.61.0.1 to 1.61.127.2541.61.127.25532,766
1241.61.128.0/171.61.128.1 to 1.61.255.2541.61.255.25532,766
1251.62.0.0/171.62.0.1 to 1.62.127.2541.62.127.25532,766
1261.62.128.0/171.62.128.1 to 1.62.255.2541.62.255.25532,766
1271.63.0.0/171.63.0.1 to 1.63.127.2541.63.127.25532,766
1281.63.128.0/171.63.128.1 to 1.63.255.2541.63.255.25532,766

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.