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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.

Network95.87.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
95.87.0.0
Broadcast address
95.87.127.255
First usable
95.87.0.1
Last usable
95.87.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
A (default /8)
As numbers
Hex 5F570000 · Integer 1599537152 to 1599569919
Reverse DNS zones
0.87.95.in-addr.arpa
1.87.95.in-addr.arpa
2.87.95.in-addr.arpa
3.87.95.in-addr.arpa
4.87.95.in-addr.arpa
5.87.95.in-addr.arpa
6.87.95.in-addr.arpa
7.87.95.in-addr.arpa
8.87.95.in-addr.arpa
9.87.95.in-addr.arpa
10.87.95.in-addr.arpa
11.87.95.in-addr.arpa
12.87.95.in-addr.arpa
13.87.95.in-addr.arpa
14.87.95.in-addr.arpa
15.87.95.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01011111.01010111.00000000.0000000095.87.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network01011111.01010111.00000000.0000000095.87.0.0
Broadcast01011111.01010111.01111111.1111111195.87.127.255
Split into smaller subnets/24
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

95.87.0.0/17 makes 128 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
195.87.0.0/2495.87.0.1 to 95.87.0.25495.87.0.255254
295.87.1.0/2495.87.1.1 to 95.87.1.25495.87.1.255254
395.87.2.0/2495.87.2.1 to 95.87.2.25495.87.2.255254
495.87.3.0/2495.87.3.1 to 95.87.3.25495.87.3.255254
595.87.4.0/2495.87.4.1 to 95.87.4.25495.87.4.255254
695.87.5.0/2495.87.5.1 to 95.87.5.25495.87.5.255254
795.87.6.0/2495.87.6.1 to 95.87.6.25495.87.6.255254
895.87.7.0/2495.87.7.1 to 95.87.7.25495.87.7.255254
995.87.8.0/2495.87.8.1 to 95.87.8.25495.87.8.255254
1095.87.9.0/2495.87.9.1 to 95.87.9.25495.87.9.255254
1195.87.10.0/2495.87.10.1 to 95.87.10.25495.87.10.255254
1295.87.11.0/2495.87.11.1 to 95.87.11.25495.87.11.255254
1395.87.12.0/2495.87.12.1 to 95.87.12.25495.87.12.255254
1495.87.13.0/2495.87.13.1 to 95.87.13.25495.87.13.255254
1595.87.14.0/2495.87.14.1 to 95.87.14.25495.87.14.255254
1695.87.15.0/2495.87.15.1 to 95.87.15.25495.87.15.255254
1795.87.16.0/2495.87.16.1 to 95.87.16.25495.87.16.255254
1895.87.17.0/2495.87.17.1 to 95.87.17.25495.87.17.255254
1995.87.18.0/2495.87.18.1 to 95.87.18.25495.87.18.255254
2095.87.19.0/2495.87.19.1 to 95.87.19.25495.87.19.255254
2195.87.20.0/2495.87.20.1 to 95.87.20.25495.87.20.255254
2295.87.21.0/2495.87.21.1 to 95.87.21.25495.87.21.255254
2395.87.22.0/2495.87.22.1 to 95.87.22.25495.87.22.255254
2495.87.23.0/2495.87.23.1 to 95.87.23.25495.87.23.255254
2595.87.24.0/2495.87.24.1 to 95.87.24.25495.87.24.255254
2695.87.25.0/2495.87.25.1 to 95.87.25.25495.87.25.255254
2795.87.26.0/2495.87.26.1 to 95.87.26.25495.87.26.255254
2895.87.27.0/2495.87.27.1 to 95.87.27.25495.87.27.255254
2995.87.28.0/2495.87.28.1 to 95.87.28.25495.87.28.255254
3095.87.29.0/2495.87.29.1 to 95.87.29.25495.87.29.255254
3195.87.30.0/2495.87.30.1 to 95.87.30.25495.87.30.255254
3295.87.31.0/2495.87.31.1 to 95.87.31.25495.87.31.255254
3395.87.32.0/2495.87.32.1 to 95.87.32.25495.87.32.255254
3495.87.33.0/2495.87.33.1 to 95.87.33.25495.87.33.255254
3595.87.34.0/2495.87.34.1 to 95.87.34.25495.87.34.255254
3695.87.35.0/2495.87.35.1 to 95.87.35.25495.87.35.255254
3795.87.36.0/2495.87.36.1 to 95.87.36.25495.87.36.255254
3895.87.37.0/2495.87.37.1 to 95.87.37.25495.87.37.255254
3995.87.38.0/2495.87.38.1 to 95.87.38.25495.87.38.255254
4095.87.39.0/2495.87.39.1 to 95.87.39.25495.87.39.255254
4195.87.40.0/2495.87.40.1 to 95.87.40.25495.87.40.255254
4295.87.41.0/2495.87.41.1 to 95.87.41.25495.87.41.255254
4395.87.42.0/2495.87.42.1 to 95.87.42.25495.87.42.255254
4495.87.43.0/2495.87.43.1 to 95.87.43.25495.87.43.255254
4595.87.44.0/2495.87.44.1 to 95.87.44.25495.87.44.255254
4695.87.45.0/2495.87.45.1 to 95.87.45.25495.87.45.255254
4795.87.46.0/2495.87.46.1 to 95.87.46.25495.87.46.255254
4895.87.47.0/2495.87.47.1 to 95.87.47.25495.87.47.255254
4995.87.48.0/2495.87.48.1 to 95.87.48.25495.87.48.255254
5095.87.49.0/2495.87.49.1 to 95.87.49.25495.87.49.255254
5195.87.50.0/2495.87.50.1 to 95.87.50.25495.87.50.255254
5295.87.51.0/2495.87.51.1 to 95.87.51.25495.87.51.255254
5395.87.52.0/2495.87.52.1 to 95.87.52.25495.87.52.255254
5495.87.53.0/2495.87.53.1 to 95.87.53.25495.87.53.255254
5595.87.54.0/2495.87.54.1 to 95.87.54.25495.87.54.255254
5695.87.55.0/2495.87.55.1 to 95.87.55.25495.87.55.255254
5795.87.56.0/2495.87.56.1 to 95.87.56.25495.87.56.255254
5895.87.57.0/2495.87.57.1 to 95.87.57.25495.87.57.255254
5995.87.58.0/2495.87.58.1 to 95.87.58.25495.87.58.255254
6095.87.59.0/2495.87.59.1 to 95.87.59.25495.87.59.255254
6195.87.60.0/2495.87.60.1 to 95.87.60.25495.87.60.255254
6295.87.61.0/2495.87.61.1 to 95.87.61.25495.87.61.255254
6395.87.62.0/2495.87.62.1 to 95.87.62.25495.87.62.255254
6495.87.63.0/2495.87.63.1 to 95.87.63.25495.87.63.255254
6595.87.64.0/2495.87.64.1 to 95.87.64.25495.87.64.255254
6695.87.65.0/2495.87.65.1 to 95.87.65.25495.87.65.255254
6795.87.66.0/2495.87.66.1 to 95.87.66.25495.87.66.255254
6895.87.67.0/2495.87.67.1 to 95.87.67.25495.87.67.255254
6995.87.68.0/2495.87.68.1 to 95.87.68.25495.87.68.255254
7095.87.69.0/2495.87.69.1 to 95.87.69.25495.87.69.255254
7195.87.70.0/2495.87.70.1 to 95.87.70.25495.87.70.255254
7295.87.71.0/2495.87.71.1 to 95.87.71.25495.87.71.255254
7395.87.72.0/2495.87.72.1 to 95.87.72.25495.87.72.255254
7495.87.73.0/2495.87.73.1 to 95.87.73.25495.87.73.255254
7595.87.74.0/2495.87.74.1 to 95.87.74.25495.87.74.255254
7695.87.75.0/2495.87.75.1 to 95.87.75.25495.87.75.255254
7795.87.76.0/2495.87.76.1 to 95.87.76.25495.87.76.255254
7895.87.77.0/2495.87.77.1 to 95.87.77.25495.87.77.255254
7995.87.78.0/2495.87.78.1 to 95.87.78.25495.87.78.255254
8095.87.79.0/2495.87.79.1 to 95.87.79.25495.87.79.255254
8195.87.80.0/2495.87.80.1 to 95.87.80.25495.87.80.255254
8295.87.81.0/2495.87.81.1 to 95.87.81.25495.87.81.255254
8395.87.82.0/2495.87.82.1 to 95.87.82.25495.87.82.255254
8495.87.83.0/2495.87.83.1 to 95.87.83.25495.87.83.255254
8595.87.84.0/2495.87.84.1 to 95.87.84.25495.87.84.255254
8695.87.85.0/2495.87.85.1 to 95.87.85.25495.87.85.255254
8795.87.86.0/2495.87.86.1 to 95.87.86.25495.87.86.255254
8895.87.87.0/2495.87.87.1 to 95.87.87.25495.87.87.255254
8995.87.88.0/2495.87.88.1 to 95.87.88.25495.87.88.255254
9095.87.89.0/2495.87.89.1 to 95.87.89.25495.87.89.255254
9195.87.90.0/2495.87.90.1 to 95.87.90.25495.87.90.255254
9295.87.91.0/2495.87.91.1 to 95.87.91.25495.87.91.255254
9395.87.92.0/2495.87.92.1 to 95.87.92.25495.87.92.255254
9495.87.93.0/2495.87.93.1 to 95.87.93.25495.87.93.255254
9595.87.94.0/2495.87.94.1 to 95.87.94.25495.87.94.255254
9695.87.95.0/2495.87.95.1 to 95.87.95.25495.87.95.255254
9795.87.96.0/2495.87.96.1 to 95.87.96.25495.87.96.255254
9895.87.97.0/2495.87.97.1 to 95.87.97.25495.87.97.255254
9995.87.98.0/2495.87.98.1 to 95.87.98.25495.87.98.255254
10095.87.99.0/2495.87.99.1 to 95.87.99.25495.87.99.255254
10195.87.100.0/2495.87.100.1 to 95.87.100.25495.87.100.255254
10295.87.101.0/2495.87.101.1 to 95.87.101.25495.87.101.255254
10395.87.102.0/2495.87.102.1 to 95.87.102.25495.87.102.255254
10495.87.103.0/2495.87.103.1 to 95.87.103.25495.87.103.255254
10595.87.104.0/2495.87.104.1 to 95.87.104.25495.87.104.255254
10695.87.105.0/2495.87.105.1 to 95.87.105.25495.87.105.255254
10795.87.106.0/2495.87.106.1 to 95.87.106.25495.87.106.255254
10895.87.107.0/2495.87.107.1 to 95.87.107.25495.87.107.255254
10995.87.108.0/2495.87.108.1 to 95.87.108.25495.87.108.255254
11095.87.109.0/2495.87.109.1 to 95.87.109.25495.87.109.255254
11195.87.110.0/2495.87.110.1 to 95.87.110.25495.87.110.255254
11295.87.111.0/2495.87.111.1 to 95.87.111.25495.87.111.255254
11395.87.112.0/2495.87.112.1 to 95.87.112.25495.87.112.255254
11495.87.113.0/2495.87.113.1 to 95.87.113.25495.87.113.255254
11595.87.114.0/2495.87.114.1 to 95.87.114.25495.87.114.255254
11695.87.115.0/2495.87.115.1 to 95.87.115.25495.87.115.255254
11795.87.116.0/2495.87.116.1 to 95.87.116.25495.87.116.255254
11895.87.117.0/2495.87.117.1 to 95.87.117.25495.87.117.255254
11995.87.118.0/2495.87.118.1 to 95.87.118.25495.87.118.255254
12095.87.119.0/2495.87.119.1 to 95.87.119.25495.87.119.255254
12195.87.120.0/2495.87.120.1 to 95.87.120.25495.87.120.255254
12295.87.121.0/2495.87.121.1 to 95.87.121.25495.87.121.255254
12395.87.122.0/2495.87.122.1 to 95.87.122.25495.87.122.255254
12495.87.123.0/2495.87.123.1 to 95.87.123.25495.87.123.255254
12595.87.124.0/2495.87.124.1 to 95.87.124.25495.87.124.255254
12695.87.125.0/2495.87.125.1 to 95.87.125.25495.87.125.255254
12795.87.126.0/2495.87.126.1 to 95.87.126.25495.87.126.255254
12895.87.127.0/2495.87.127.1 to 95.87.127.25495.87.127.255254

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.