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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.

Network225.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
225.0.0.0
Broadcast address
225.63.255.255
First usable
225.0.0.1
Last usable
225.63.255.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E1000000 · Integer 3774873600 to 3779067903
Reverse DNS zones
0.225.in-addr.arpa
1.225.in-addr.arpa
2.225.in-addr.arpa
3.225.in-addr.arpa
4.225.in-addr.arpa
5.225.in-addr.arpa
6.225.in-addr.arpa
7.225.in-addr.arpa
8.225.in-addr.arpa
9.225.in-addr.arpa
10.225.in-addr.arpa
11.225.in-addr.arpa
12.225.in-addr.arpa
13.225.in-addr.arpa
14.225.in-addr.arpa
15.225.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
Address11100001.00000000.00000000.00000000225.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network11100001.00000000.00000000.00000000225.0.0.0
Broadcast11100001.00111111.11111111.11111111225.63.255.255
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)

225.0.0.0/10 makes 128 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1225.0.0.0/17225.0.0.1 to 225.0.127.254225.0.127.25532,766
2225.0.128.0/17225.0.128.1 to 225.0.255.254225.0.255.25532,766
3225.1.0.0/17225.1.0.1 to 225.1.127.254225.1.127.25532,766
4225.1.128.0/17225.1.128.1 to 225.1.255.254225.1.255.25532,766
5225.2.0.0/17225.2.0.1 to 225.2.127.254225.2.127.25532,766
6225.2.128.0/17225.2.128.1 to 225.2.255.254225.2.255.25532,766
7225.3.0.0/17225.3.0.1 to 225.3.127.254225.3.127.25532,766
8225.3.128.0/17225.3.128.1 to 225.3.255.254225.3.255.25532,766
9225.4.0.0/17225.4.0.1 to 225.4.127.254225.4.127.25532,766
10225.4.128.0/17225.4.128.1 to 225.4.255.254225.4.255.25532,766
11225.5.0.0/17225.5.0.1 to 225.5.127.254225.5.127.25532,766
12225.5.128.0/17225.5.128.1 to 225.5.255.254225.5.255.25532,766
13225.6.0.0/17225.6.0.1 to 225.6.127.254225.6.127.25532,766
14225.6.128.0/17225.6.128.1 to 225.6.255.254225.6.255.25532,766
15225.7.0.0/17225.7.0.1 to 225.7.127.254225.7.127.25532,766
16225.7.128.0/17225.7.128.1 to 225.7.255.254225.7.255.25532,766
17225.8.0.0/17225.8.0.1 to 225.8.127.254225.8.127.25532,766
18225.8.128.0/17225.8.128.1 to 225.8.255.254225.8.255.25532,766
19225.9.0.0/17225.9.0.1 to 225.9.127.254225.9.127.25532,766
20225.9.128.0/17225.9.128.1 to 225.9.255.254225.9.255.25532,766
21225.10.0.0/17225.10.0.1 to 225.10.127.254225.10.127.25532,766
22225.10.128.0/17225.10.128.1 to 225.10.255.254225.10.255.25532,766
23225.11.0.0/17225.11.0.1 to 225.11.127.254225.11.127.25532,766
24225.11.128.0/17225.11.128.1 to 225.11.255.254225.11.255.25532,766
25225.12.0.0/17225.12.0.1 to 225.12.127.254225.12.127.25532,766
26225.12.128.0/17225.12.128.1 to 225.12.255.254225.12.255.25532,766
27225.13.0.0/17225.13.0.1 to 225.13.127.254225.13.127.25532,766
28225.13.128.0/17225.13.128.1 to 225.13.255.254225.13.255.25532,766
29225.14.0.0/17225.14.0.1 to 225.14.127.254225.14.127.25532,766
30225.14.128.0/17225.14.128.1 to 225.14.255.254225.14.255.25532,766
31225.15.0.0/17225.15.0.1 to 225.15.127.254225.15.127.25532,766
32225.15.128.0/17225.15.128.1 to 225.15.255.254225.15.255.25532,766
33225.16.0.0/17225.16.0.1 to 225.16.127.254225.16.127.25532,766
34225.16.128.0/17225.16.128.1 to 225.16.255.254225.16.255.25532,766
35225.17.0.0/17225.17.0.1 to 225.17.127.254225.17.127.25532,766
36225.17.128.0/17225.17.128.1 to 225.17.255.254225.17.255.25532,766
37225.18.0.0/17225.18.0.1 to 225.18.127.254225.18.127.25532,766
38225.18.128.0/17225.18.128.1 to 225.18.255.254225.18.255.25532,766
39225.19.0.0/17225.19.0.1 to 225.19.127.254225.19.127.25532,766
40225.19.128.0/17225.19.128.1 to 225.19.255.254225.19.255.25532,766
41225.20.0.0/17225.20.0.1 to 225.20.127.254225.20.127.25532,766
42225.20.128.0/17225.20.128.1 to 225.20.255.254225.20.255.25532,766
43225.21.0.0/17225.21.0.1 to 225.21.127.254225.21.127.25532,766
44225.21.128.0/17225.21.128.1 to 225.21.255.254225.21.255.25532,766
45225.22.0.0/17225.22.0.1 to 225.22.127.254225.22.127.25532,766
46225.22.128.0/17225.22.128.1 to 225.22.255.254225.22.255.25532,766
47225.23.0.0/17225.23.0.1 to 225.23.127.254225.23.127.25532,766
48225.23.128.0/17225.23.128.1 to 225.23.255.254225.23.255.25532,766
49225.24.0.0/17225.24.0.1 to 225.24.127.254225.24.127.25532,766
50225.24.128.0/17225.24.128.1 to 225.24.255.254225.24.255.25532,766
51225.25.0.0/17225.25.0.1 to 225.25.127.254225.25.127.25532,766
52225.25.128.0/17225.25.128.1 to 225.25.255.254225.25.255.25532,766
53225.26.0.0/17225.26.0.1 to 225.26.127.254225.26.127.25532,766
54225.26.128.0/17225.26.128.1 to 225.26.255.254225.26.255.25532,766
55225.27.0.0/17225.27.0.1 to 225.27.127.254225.27.127.25532,766
56225.27.128.0/17225.27.128.1 to 225.27.255.254225.27.255.25532,766
57225.28.0.0/17225.28.0.1 to 225.28.127.254225.28.127.25532,766
58225.28.128.0/17225.28.128.1 to 225.28.255.254225.28.255.25532,766
59225.29.0.0/17225.29.0.1 to 225.29.127.254225.29.127.25532,766
60225.29.128.0/17225.29.128.1 to 225.29.255.254225.29.255.25532,766
61225.30.0.0/17225.30.0.1 to 225.30.127.254225.30.127.25532,766
62225.30.128.0/17225.30.128.1 to 225.30.255.254225.30.255.25532,766
63225.31.0.0/17225.31.0.1 to 225.31.127.254225.31.127.25532,766
64225.31.128.0/17225.31.128.1 to 225.31.255.254225.31.255.25532,766
65225.32.0.0/17225.32.0.1 to 225.32.127.254225.32.127.25532,766
66225.32.128.0/17225.32.128.1 to 225.32.255.254225.32.255.25532,766
67225.33.0.0/17225.33.0.1 to 225.33.127.254225.33.127.25532,766
68225.33.128.0/17225.33.128.1 to 225.33.255.254225.33.255.25532,766
69225.34.0.0/17225.34.0.1 to 225.34.127.254225.34.127.25532,766
70225.34.128.0/17225.34.128.1 to 225.34.255.254225.34.255.25532,766
71225.35.0.0/17225.35.0.1 to 225.35.127.254225.35.127.25532,766
72225.35.128.0/17225.35.128.1 to 225.35.255.254225.35.255.25532,766
73225.36.0.0/17225.36.0.1 to 225.36.127.254225.36.127.25532,766
74225.36.128.0/17225.36.128.1 to 225.36.255.254225.36.255.25532,766
75225.37.0.0/17225.37.0.1 to 225.37.127.254225.37.127.25532,766
76225.37.128.0/17225.37.128.1 to 225.37.255.254225.37.255.25532,766
77225.38.0.0/17225.38.0.1 to 225.38.127.254225.38.127.25532,766
78225.38.128.0/17225.38.128.1 to 225.38.255.254225.38.255.25532,766
79225.39.0.0/17225.39.0.1 to 225.39.127.254225.39.127.25532,766
80225.39.128.0/17225.39.128.1 to 225.39.255.254225.39.255.25532,766
81225.40.0.0/17225.40.0.1 to 225.40.127.254225.40.127.25532,766
82225.40.128.0/17225.40.128.1 to 225.40.255.254225.40.255.25532,766
83225.41.0.0/17225.41.0.1 to 225.41.127.254225.41.127.25532,766
84225.41.128.0/17225.41.128.1 to 225.41.255.254225.41.255.25532,766
85225.42.0.0/17225.42.0.1 to 225.42.127.254225.42.127.25532,766
86225.42.128.0/17225.42.128.1 to 225.42.255.254225.42.255.25532,766
87225.43.0.0/17225.43.0.1 to 225.43.127.254225.43.127.25532,766
88225.43.128.0/17225.43.128.1 to 225.43.255.254225.43.255.25532,766
89225.44.0.0/17225.44.0.1 to 225.44.127.254225.44.127.25532,766
90225.44.128.0/17225.44.128.1 to 225.44.255.254225.44.255.25532,766
91225.45.0.0/17225.45.0.1 to 225.45.127.254225.45.127.25532,766
92225.45.128.0/17225.45.128.1 to 225.45.255.254225.45.255.25532,766
93225.46.0.0/17225.46.0.1 to 225.46.127.254225.46.127.25532,766
94225.46.128.0/17225.46.128.1 to 225.46.255.254225.46.255.25532,766
95225.47.0.0/17225.47.0.1 to 225.47.127.254225.47.127.25532,766
96225.47.128.0/17225.47.128.1 to 225.47.255.254225.47.255.25532,766
97225.48.0.0/17225.48.0.1 to 225.48.127.254225.48.127.25532,766
98225.48.128.0/17225.48.128.1 to 225.48.255.254225.48.255.25532,766
99225.49.0.0/17225.49.0.1 to 225.49.127.254225.49.127.25532,766
100225.49.128.0/17225.49.128.1 to 225.49.255.254225.49.255.25532,766
101225.50.0.0/17225.50.0.1 to 225.50.127.254225.50.127.25532,766
102225.50.128.0/17225.50.128.1 to 225.50.255.254225.50.255.25532,766
103225.51.0.0/17225.51.0.1 to 225.51.127.254225.51.127.25532,766
104225.51.128.0/17225.51.128.1 to 225.51.255.254225.51.255.25532,766
105225.52.0.0/17225.52.0.1 to 225.52.127.254225.52.127.25532,766
106225.52.128.0/17225.52.128.1 to 225.52.255.254225.52.255.25532,766
107225.53.0.0/17225.53.0.1 to 225.53.127.254225.53.127.25532,766
108225.53.128.0/17225.53.128.1 to 225.53.255.254225.53.255.25532,766
109225.54.0.0/17225.54.0.1 to 225.54.127.254225.54.127.25532,766
110225.54.128.0/17225.54.128.1 to 225.54.255.254225.54.255.25532,766
111225.55.0.0/17225.55.0.1 to 225.55.127.254225.55.127.25532,766
112225.55.128.0/17225.55.128.1 to 225.55.255.254225.55.255.25532,766
113225.56.0.0/17225.56.0.1 to 225.56.127.254225.56.127.25532,766
114225.56.128.0/17225.56.128.1 to 225.56.255.254225.56.255.25532,766
115225.57.0.0/17225.57.0.1 to 225.57.127.254225.57.127.25532,766
116225.57.128.0/17225.57.128.1 to 225.57.255.254225.57.255.25532,766
117225.58.0.0/17225.58.0.1 to 225.58.127.254225.58.127.25532,766
118225.58.128.0/17225.58.128.1 to 225.58.255.254225.58.255.25532,766
119225.59.0.0/17225.59.0.1 to 225.59.127.254225.59.127.25532,766
120225.59.128.0/17225.59.128.1 to 225.59.255.254225.59.255.25532,766
121225.60.0.0/17225.60.0.1 to 225.60.127.254225.60.127.25532,766
122225.60.128.0/17225.60.128.1 to 225.60.255.254225.60.255.25532,766
123225.61.0.0/17225.61.0.1 to 225.61.127.254225.61.127.25532,766
124225.61.128.0/17225.61.128.1 to 225.61.255.254225.61.255.25532,766
125225.62.0.0/17225.62.0.1 to 225.62.127.254225.62.127.25532,766
126225.62.128.0/17225.62.128.1 to 225.62.255.254225.62.255.25532,766
127225.63.0.0/17225.63.0.1 to 225.63.127.254225.63.127.25532,766
128225.63.128.0/17225.63.128.1 to 225.63.255.254225.63.255.25532,766

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.