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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.

Network127.230.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
127.230.0.0
Broadcast address
127.231.255.255
First usable
127.230.0.1
Last usable
127.231.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Loopback 127.0.0.0/8
This computer
Old class
A (default /8)
As numbers
Hex 7FE60000 · Integer 2145779712 to 2145910783
Reverse DNS zones
230.127.in-addr.arpa
231.127.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01111111.11100110.00000000.00000000127.230.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network01111111.11100110.00000000.00000000127.230.0.0
Broadcast01111111.11100111.11111111.11111111127.231.255.255
Split into smaller subnets/22
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

127.230.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1127.230.0.0/22127.230.0.1 to 127.230.3.254127.230.3.2551,022
2127.230.4.0/22127.230.4.1 to 127.230.7.254127.230.7.2551,022
3127.230.8.0/22127.230.8.1 to 127.230.11.254127.230.11.2551,022
4127.230.12.0/22127.230.12.1 to 127.230.15.254127.230.15.2551,022
5127.230.16.0/22127.230.16.1 to 127.230.19.254127.230.19.2551,022
6127.230.20.0/22127.230.20.1 to 127.230.23.254127.230.23.2551,022
7127.230.24.0/22127.230.24.1 to 127.230.27.254127.230.27.2551,022
8127.230.28.0/22127.230.28.1 to 127.230.31.254127.230.31.2551,022
9127.230.32.0/22127.230.32.1 to 127.230.35.254127.230.35.2551,022
10127.230.36.0/22127.230.36.1 to 127.230.39.254127.230.39.2551,022
11127.230.40.0/22127.230.40.1 to 127.230.43.254127.230.43.2551,022
12127.230.44.0/22127.230.44.1 to 127.230.47.254127.230.47.2551,022
13127.230.48.0/22127.230.48.1 to 127.230.51.254127.230.51.2551,022
14127.230.52.0/22127.230.52.1 to 127.230.55.254127.230.55.2551,022
15127.230.56.0/22127.230.56.1 to 127.230.59.254127.230.59.2551,022
16127.230.60.0/22127.230.60.1 to 127.230.63.254127.230.63.2551,022
17127.230.64.0/22127.230.64.1 to 127.230.67.254127.230.67.2551,022
18127.230.68.0/22127.230.68.1 to 127.230.71.254127.230.71.2551,022
19127.230.72.0/22127.230.72.1 to 127.230.75.254127.230.75.2551,022
20127.230.76.0/22127.230.76.1 to 127.230.79.254127.230.79.2551,022
21127.230.80.0/22127.230.80.1 to 127.230.83.254127.230.83.2551,022
22127.230.84.0/22127.230.84.1 to 127.230.87.254127.230.87.2551,022
23127.230.88.0/22127.230.88.1 to 127.230.91.254127.230.91.2551,022
24127.230.92.0/22127.230.92.1 to 127.230.95.254127.230.95.2551,022
25127.230.96.0/22127.230.96.1 to 127.230.99.254127.230.99.2551,022
26127.230.100.0/22127.230.100.1 to 127.230.103.254127.230.103.2551,022
27127.230.104.0/22127.230.104.1 to 127.230.107.254127.230.107.2551,022
28127.230.108.0/22127.230.108.1 to 127.230.111.254127.230.111.2551,022
29127.230.112.0/22127.230.112.1 to 127.230.115.254127.230.115.2551,022
30127.230.116.0/22127.230.116.1 to 127.230.119.254127.230.119.2551,022
31127.230.120.0/22127.230.120.1 to 127.230.123.254127.230.123.2551,022
32127.230.124.0/22127.230.124.1 to 127.230.127.254127.230.127.2551,022
33127.230.128.0/22127.230.128.1 to 127.230.131.254127.230.131.2551,022
34127.230.132.0/22127.230.132.1 to 127.230.135.254127.230.135.2551,022
35127.230.136.0/22127.230.136.1 to 127.230.139.254127.230.139.2551,022
36127.230.140.0/22127.230.140.1 to 127.230.143.254127.230.143.2551,022
37127.230.144.0/22127.230.144.1 to 127.230.147.254127.230.147.2551,022
38127.230.148.0/22127.230.148.1 to 127.230.151.254127.230.151.2551,022
39127.230.152.0/22127.230.152.1 to 127.230.155.254127.230.155.2551,022
40127.230.156.0/22127.230.156.1 to 127.230.159.254127.230.159.2551,022
41127.230.160.0/22127.230.160.1 to 127.230.163.254127.230.163.2551,022
42127.230.164.0/22127.230.164.1 to 127.230.167.254127.230.167.2551,022
43127.230.168.0/22127.230.168.1 to 127.230.171.254127.230.171.2551,022
44127.230.172.0/22127.230.172.1 to 127.230.175.254127.230.175.2551,022
45127.230.176.0/22127.230.176.1 to 127.230.179.254127.230.179.2551,022
46127.230.180.0/22127.230.180.1 to 127.230.183.254127.230.183.2551,022
47127.230.184.0/22127.230.184.1 to 127.230.187.254127.230.187.2551,022
48127.230.188.0/22127.230.188.1 to 127.230.191.254127.230.191.2551,022
49127.230.192.0/22127.230.192.1 to 127.230.195.254127.230.195.2551,022
50127.230.196.0/22127.230.196.1 to 127.230.199.254127.230.199.2551,022
51127.230.200.0/22127.230.200.1 to 127.230.203.254127.230.203.2551,022
52127.230.204.0/22127.230.204.1 to 127.230.207.254127.230.207.2551,022
53127.230.208.0/22127.230.208.1 to 127.230.211.254127.230.211.2551,022
54127.230.212.0/22127.230.212.1 to 127.230.215.254127.230.215.2551,022
55127.230.216.0/22127.230.216.1 to 127.230.219.254127.230.219.2551,022
56127.230.220.0/22127.230.220.1 to 127.230.223.254127.230.223.2551,022
57127.230.224.0/22127.230.224.1 to 127.230.227.254127.230.227.2551,022
58127.230.228.0/22127.230.228.1 to 127.230.231.254127.230.231.2551,022
59127.230.232.0/22127.230.232.1 to 127.230.235.254127.230.235.2551,022
60127.230.236.0/22127.230.236.1 to 127.230.239.254127.230.239.2551,022
61127.230.240.0/22127.230.240.1 to 127.230.243.254127.230.243.2551,022
62127.230.244.0/22127.230.244.1 to 127.230.247.254127.230.247.2551,022
63127.230.248.0/22127.230.248.1 to 127.230.251.254127.230.251.2551,022
64127.230.252.0/22127.230.252.1 to 127.230.255.254127.230.255.2551,022
65127.231.0.0/22127.231.0.1 to 127.231.3.254127.231.3.2551,022
66127.231.4.0/22127.231.4.1 to 127.231.7.254127.231.7.2551,022
67127.231.8.0/22127.231.8.1 to 127.231.11.254127.231.11.2551,022
68127.231.12.0/22127.231.12.1 to 127.231.15.254127.231.15.2551,022
69127.231.16.0/22127.231.16.1 to 127.231.19.254127.231.19.2551,022
70127.231.20.0/22127.231.20.1 to 127.231.23.254127.231.23.2551,022
71127.231.24.0/22127.231.24.1 to 127.231.27.254127.231.27.2551,022
72127.231.28.0/22127.231.28.1 to 127.231.31.254127.231.31.2551,022
73127.231.32.0/22127.231.32.1 to 127.231.35.254127.231.35.2551,022
74127.231.36.0/22127.231.36.1 to 127.231.39.254127.231.39.2551,022
75127.231.40.0/22127.231.40.1 to 127.231.43.254127.231.43.2551,022
76127.231.44.0/22127.231.44.1 to 127.231.47.254127.231.47.2551,022
77127.231.48.0/22127.231.48.1 to 127.231.51.254127.231.51.2551,022
78127.231.52.0/22127.231.52.1 to 127.231.55.254127.231.55.2551,022
79127.231.56.0/22127.231.56.1 to 127.231.59.254127.231.59.2551,022
80127.231.60.0/22127.231.60.1 to 127.231.63.254127.231.63.2551,022
81127.231.64.0/22127.231.64.1 to 127.231.67.254127.231.67.2551,022
82127.231.68.0/22127.231.68.1 to 127.231.71.254127.231.71.2551,022
83127.231.72.0/22127.231.72.1 to 127.231.75.254127.231.75.2551,022
84127.231.76.0/22127.231.76.1 to 127.231.79.254127.231.79.2551,022
85127.231.80.0/22127.231.80.1 to 127.231.83.254127.231.83.2551,022
86127.231.84.0/22127.231.84.1 to 127.231.87.254127.231.87.2551,022
87127.231.88.0/22127.231.88.1 to 127.231.91.254127.231.91.2551,022
88127.231.92.0/22127.231.92.1 to 127.231.95.254127.231.95.2551,022
89127.231.96.0/22127.231.96.1 to 127.231.99.254127.231.99.2551,022
90127.231.100.0/22127.231.100.1 to 127.231.103.254127.231.103.2551,022
91127.231.104.0/22127.231.104.1 to 127.231.107.254127.231.107.2551,022
92127.231.108.0/22127.231.108.1 to 127.231.111.254127.231.111.2551,022
93127.231.112.0/22127.231.112.1 to 127.231.115.254127.231.115.2551,022
94127.231.116.0/22127.231.116.1 to 127.231.119.254127.231.119.2551,022
95127.231.120.0/22127.231.120.1 to 127.231.123.254127.231.123.2551,022
96127.231.124.0/22127.231.124.1 to 127.231.127.254127.231.127.2551,022
97127.231.128.0/22127.231.128.1 to 127.231.131.254127.231.131.2551,022
98127.231.132.0/22127.231.132.1 to 127.231.135.254127.231.135.2551,022
99127.231.136.0/22127.231.136.1 to 127.231.139.254127.231.139.2551,022
100127.231.140.0/22127.231.140.1 to 127.231.143.254127.231.143.2551,022
101127.231.144.0/22127.231.144.1 to 127.231.147.254127.231.147.2551,022
102127.231.148.0/22127.231.148.1 to 127.231.151.254127.231.151.2551,022
103127.231.152.0/22127.231.152.1 to 127.231.155.254127.231.155.2551,022
104127.231.156.0/22127.231.156.1 to 127.231.159.254127.231.159.2551,022
105127.231.160.0/22127.231.160.1 to 127.231.163.254127.231.163.2551,022
106127.231.164.0/22127.231.164.1 to 127.231.167.254127.231.167.2551,022
107127.231.168.0/22127.231.168.1 to 127.231.171.254127.231.171.2551,022
108127.231.172.0/22127.231.172.1 to 127.231.175.254127.231.175.2551,022
109127.231.176.0/22127.231.176.1 to 127.231.179.254127.231.179.2551,022
110127.231.180.0/22127.231.180.1 to 127.231.183.254127.231.183.2551,022
111127.231.184.0/22127.231.184.1 to 127.231.187.254127.231.187.2551,022
112127.231.188.0/22127.231.188.1 to 127.231.191.254127.231.191.2551,022
113127.231.192.0/22127.231.192.1 to 127.231.195.254127.231.195.2551,022
114127.231.196.0/22127.231.196.1 to 127.231.199.254127.231.199.2551,022
115127.231.200.0/22127.231.200.1 to 127.231.203.254127.231.203.2551,022
116127.231.204.0/22127.231.204.1 to 127.231.207.254127.231.207.2551,022
117127.231.208.0/22127.231.208.1 to 127.231.211.254127.231.211.2551,022
118127.231.212.0/22127.231.212.1 to 127.231.215.254127.231.215.2551,022
119127.231.216.0/22127.231.216.1 to 127.231.219.254127.231.219.2551,022
120127.231.220.0/22127.231.220.1 to 127.231.223.254127.231.223.2551,022
121127.231.224.0/22127.231.224.1 to 127.231.227.254127.231.227.2551,022
122127.231.228.0/22127.231.228.1 to 127.231.231.254127.231.231.2551,022
123127.231.232.0/22127.231.232.1 to 127.231.235.254127.231.235.2551,022
124127.231.236.0/22127.231.236.1 to 127.231.239.254127.231.239.2551,022
125127.231.240.0/22127.231.240.1 to 127.231.243.254127.231.243.2551,022
126127.231.244.0/22127.231.244.1 to 127.231.247.254127.231.247.2551,022
127127.231.248.0/22127.231.248.1 to 127.231.251.254127.231.251.2551,022
128127.231.252.0/22127.231.252.1 to 127.231.255.254127.231.255.2551,022

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.