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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.

Network192.0.0.0/2
Usable hosts1,073,741,822
Subnet mask192.0.0.0
Addresses1,073,741,824
Network address
192.0.0.0
Broadcast address
255.255.255.255
First usable
192.0.0.1
Last usable
255.255.255.254
Usable hosts
1,073,741,822 (1,073,741,824 less the network and broadcast addresses)
Subnet mask
192.0.0.0
Wildcard mask
63.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/2
Type
Public public
Old class
C (default /24)
As numbers
Hex C0000000 · Integer 3221225472 to 4294967295
Reverse DNS zones
192.in-addr.arpa
193.in-addr.arpa
194.in-addr.arpa
195.in-addr.arpa
196.in-addr.arpa
197.in-addr.arpa
198.in-addr.arpa
199.in-addr.arpa
200.in-addr.arpa
201.in-addr.arpa
202.in-addr.arpa
203.in-addr.arpa
204.in-addr.arpa
205.in-addr.arpa
206.in-addr.arpa
207.in-addr.arpa
and 48 more
/2 is not on a 8-bit boundary, so it takes 64 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11000000.00000000.00000000.00000000192.0.0.0
Subnet mask11000000.00000000.00000000.00000000192.0.0.0
Network11000000.00000000.00000000.00000000192.0.0.0
Broadcast11111111.11111111.11111111.11111111255.255.255.255
Split into smaller subnets/9
/3 (2)/4 (4)/5 (8)/6 (16)/7 (32)/8 (64)/9 (128)/10 (256)/11 (512)/12 (1,024)/13 (2,048)/14 (4,096)

192.0.0.0/2 makes 128 subnets of /9.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1192.0.0.0/9192.0.0.1 to 192.127.255.254192.127.255.2558,388,606
2192.128.0.0/9192.128.0.1 to 192.255.255.254192.255.255.2558,388,606
3193.0.0.0/9193.0.0.1 to 193.127.255.254193.127.255.2558,388,606
4193.128.0.0/9193.128.0.1 to 193.255.255.254193.255.255.2558,388,606
5194.0.0.0/9194.0.0.1 to 194.127.255.254194.127.255.2558,388,606
6194.128.0.0/9194.128.0.1 to 194.255.255.254194.255.255.2558,388,606
7195.0.0.0/9195.0.0.1 to 195.127.255.254195.127.255.2558,388,606
8195.128.0.0/9195.128.0.1 to 195.255.255.254195.255.255.2558,388,606
9196.0.0.0/9196.0.0.1 to 196.127.255.254196.127.255.2558,388,606
10196.128.0.0/9196.128.0.1 to 196.255.255.254196.255.255.2558,388,606
11197.0.0.0/9197.0.0.1 to 197.127.255.254197.127.255.2558,388,606
12197.128.0.0/9197.128.0.1 to 197.255.255.254197.255.255.2558,388,606
13198.0.0.0/9198.0.0.1 to 198.127.255.254198.127.255.2558,388,606
14198.128.0.0/9198.128.0.1 to 198.255.255.254198.255.255.2558,388,606
15199.0.0.0/9199.0.0.1 to 199.127.255.254199.127.255.2558,388,606
16199.128.0.0/9199.128.0.1 to 199.255.255.254199.255.255.2558,388,606
17200.0.0.0/9200.0.0.1 to 200.127.255.254200.127.255.2558,388,606
18200.128.0.0/9200.128.0.1 to 200.255.255.254200.255.255.2558,388,606
19201.0.0.0/9201.0.0.1 to 201.127.255.254201.127.255.2558,388,606
20201.128.0.0/9201.128.0.1 to 201.255.255.254201.255.255.2558,388,606
21202.0.0.0/9202.0.0.1 to 202.127.255.254202.127.255.2558,388,606
22202.128.0.0/9202.128.0.1 to 202.255.255.254202.255.255.2558,388,606
23203.0.0.0/9203.0.0.1 to 203.127.255.254203.127.255.2558,388,606
24203.128.0.0/9203.128.0.1 to 203.255.255.254203.255.255.2558,388,606
25204.0.0.0/9204.0.0.1 to 204.127.255.254204.127.255.2558,388,606
26204.128.0.0/9204.128.0.1 to 204.255.255.254204.255.255.2558,388,606
27205.0.0.0/9205.0.0.1 to 205.127.255.254205.127.255.2558,388,606
28205.128.0.0/9205.128.0.1 to 205.255.255.254205.255.255.2558,388,606
29206.0.0.0/9206.0.0.1 to 206.127.255.254206.127.255.2558,388,606
30206.128.0.0/9206.128.0.1 to 206.255.255.254206.255.255.2558,388,606
31207.0.0.0/9207.0.0.1 to 207.127.255.254207.127.255.2558,388,606
32207.128.0.0/9207.128.0.1 to 207.255.255.254207.255.255.2558,388,606
33208.0.0.0/9208.0.0.1 to 208.127.255.254208.127.255.2558,388,606
34208.128.0.0/9208.128.0.1 to 208.255.255.254208.255.255.2558,388,606
35209.0.0.0/9209.0.0.1 to 209.127.255.254209.127.255.2558,388,606
36209.128.0.0/9209.128.0.1 to 209.255.255.254209.255.255.2558,388,606
37210.0.0.0/9210.0.0.1 to 210.127.255.254210.127.255.2558,388,606
38210.128.0.0/9210.128.0.1 to 210.255.255.254210.255.255.2558,388,606
39211.0.0.0/9211.0.0.1 to 211.127.255.254211.127.255.2558,388,606
40211.128.0.0/9211.128.0.1 to 211.255.255.254211.255.255.2558,388,606
41212.0.0.0/9212.0.0.1 to 212.127.255.254212.127.255.2558,388,606
42212.128.0.0/9212.128.0.1 to 212.255.255.254212.255.255.2558,388,606
43213.0.0.0/9213.0.0.1 to 213.127.255.254213.127.255.2558,388,606
44213.128.0.0/9213.128.0.1 to 213.255.255.254213.255.255.2558,388,606
45214.0.0.0/9214.0.0.1 to 214.127.255.254214.127.255.2558,388,606
46214.128.0.0/9214.128.0.1 to 214.255.255.254214.255.255.2558,388,606
47215.0.0.0/9215.0.0.1 to 215.127.255.254215.127.255.2558,388,606
48215.128.0.0/9215.128.0.1 to 215.255.255.254215.255.255.2558,388,606
49216.0.0.0/9216.0.0.1 to 216.127.255.254216.127.255.2558,388,606
50216.128.0.0/9216.128.0.1 to 216.255.255.254216.255.255.2558,388,606
51217.0.0.0/9217.0.0.1 to 217.127.255.254217.127.255.2558,388,606
52217.128.0.0/9217.128.0.1 to 217.255.255.254217.255.255.2558,388,606
53218.0.0.0/9218.0.0.1 to 218.127.255.254218.127.255.2558,388,606
54218.128.0.0/9218.128.0.1 to 218.255.255.254218.255.255.2558,388,606
55219.0.0.0/9219.0.0.1 to 219.127.255.254219.127.255.2558,388,606
56219.128.0.0/9219.128.0.1 to 219.255.255.254219.255.255.2558,388,606
57220.0.0.0/9220.0.0.1 to 220.127.255.254220.127.255.2558,388,606
58220.128.0.0/9220.128.0.1 to 220.255.255.254220.255.255.2558,388,606
59221.0.0.0/9221.0.0.1 to 221.127.255.254221.127.255.2558,388,606
60221.128.0.0/9221.128.0.1 to 221.255.255.254221.255.255.2558,388,606
61222.0.0.0/9222.0.0.1 to 222.127.255.254222.127.255.2558,388,606
62222.128.0.0/9222.128.0.1 to 222.255.255.254222.255.255.2558,388,606
63223.0.0.0/9223.0.0.1 to 223.127.255.254223.127.255.2558,388,606
64223.128.0.0/9223.128.0.1 to 223.255.255.254223.255.255.2558,388,606
65224.0.0.0/9224.0.0.1 to 224.127.255.254224.127.255.2558,388,606
66224.128.0.0/9224.128.0.1 to 224.255.255.254224.255.255.2558,388,606
67225.0.0.0/9225.0.0.1 to 225.127.255.254225.127.255.2558,388,606
68225.128.0.0/9225.128.0.1 to 225.255.255.254225.255.255.2558,388,606
69226.0.0.0/9226.0.0.1 to 226.127.255.254226.127.255.2558,388,606
70226.128.0.0/9226.128.0.1 to 226.255.255.254226.255.255.2558,388,606
71227.0.0.0/9227.0.0.1 to 227.127.255.254227.127.255.2558,388,606
72227.128.0.0/9227.128.0.1 to 227.255.255.254227.255.255.2558,388,606
73228.0.0.0/9228.0.0.1 to 228.127.255.254228.127.255.2558,388,606
74228.128.0.0/9228.128.0.1 to 228.255.255.254228.255.255.2558,388,606
75229.0.0.0/9229.0.0.1 to 229.127.255.254229.127.255.2558,388,606
76229.128.0.0/9229.128.0.1 to 229.255.255.254229.255.255.2558,388,606
77230.0.0.0/9230.0.0.1 to 230.127.255.254230.127.255.2558,388,606
78230.128.0.0/9230.128.0.1 to 230.255.255.254230.255.255.2558,388,606
79231.0.0.0/9231.0.0.1 to 231.127.255.254231.127.255.2558,388,606
80231.128.0.0/9231.128.0.1 to 231.255.255.254231.255.255.2558,388,606
81232.0.0.0/9232.0.0.1 to 232.127.255.254232.127.255.2558,388,606
82232.128.0.0/9232.128.0.1 to 232.255.255.254232.255.255.2558,388,606
83233.0.0.0/9233.0.0.1 to 233.127.255.254233.127.255.2558,388,606
84233.128.0.0/9233.128.0.1 to 233.255.255.254233.255.255.2558,388,606
85234.0.0.0/9234.0.0.1 to 234.127.255.254234.127.255.2558,388,606
86234.128.0.0/9234.128.0.1 to 234.255.255.254234.255.255.2558,388,606
87235.0.0.0/9235.0.0.1 to 235.127.255.254235.127.255.2558,388,606
88235.128.0.0/9235.128.0.1 to 235.255.255.254235.255.255.2558,388,606
89236.0.0.0/9236.0.0.1 to 236.127.255.254236.127.255.2558,388,606
90236.128.0.0/9236.128.0.1 to 236.255.255.254236.255.255.2558,388,606
91237.0.0.0/9237.0.0.1 to 237.127.255.254237.127.255.2558,388,606
92237.128.0.0/9237.128.0.1 to 237.255.255.254237.255.255.2558,388,606
93238.0.0.0/9238.0.0.1 to 238.127.255.254238.127.255.2558,388,606
94238.128.0.0/9238.128.0.1 to 238.255.255.254238.255.255.2558,388,606
95239.0.0.0/9239.0.0.1 to 239.127.255.254239.127.255.2558,388,606
96239.128.0.0/9239.128.0.1 to 239.255.255.254239.255.255.2558,388,606
97240.0.0.0/9240.0.0.1 to 240.127.255.254240.127.255.2558,388,606
98240.128.0.0/9240.128.0.1 to 240.255.255.254240.255.255.2558,388,606
99241.0.0.0/9241.0.0.1 to 241.127.255.254241.127.255.2558,388,606
100241.128.0.0/9241.128.0.1 to 241.255.255.254241.255.255.2558,388,606
101242.0.0.0/9242.0.0.1 to 242.127.255.254242.127.255.2558,388,606
102242.128.0.0/9242.128.0.1 to 242.255.255.254242.255.255.2558,388,606
103243.0.0.0/9243.0.0.1 to 243.127.255.254243.127.255.2558,388,606
104243.128.0.0/9243.128.0.1 to 243.255.255.254243.255.255.2558,388,606
105244.0.0.0/9244.0.0.1 to 244.127.255.254244.127.255.2558,388,606
106244.128.0.0/9244.128.0.1 to 244.255.255.254244.255.255.2558,388,606
107245.0.0.0/9245.0.0.1 to 245.127.255.254245.127.255.2558,388,606
108245.128.0.0/9245.128.0.1 to 245.255.255.254245.255.255.2558,388,606
109246.0.0.0/9246.0.0.1 to 246.127.255.254246.127.255.2558,388,606
110246.128.0.0/9246.128.0.1 to 246.255.255.254246.255.255.2558,388,606
111247.0.0.0/9247.0.0.1 to 247.127.255.254247.127.255.2558,388,606
112247.128.0.0/9247.128.0.1 to 247.255.255.254247.255.255.2558,388,606
113248.0.0.0/9248.0.0.1 to 248.127.255.254248.127.255.2558,388,606
114248.128.0.0/9248.128.0.1 to 248.255.255.254248.255.255.2558,388,606
115249.0.0.0/9249.0.0.1 to 249.127.255.254249.127.255.2558,388,606
116249.128.0.0/9249.128.0.1 to 249.255.255.254249.255.255.2558,388,606
117250.0.0.0/9250.0.0.1 to 250.127.255.254250.127.255.2558,388,606
118250.128.0.0/9250.128.0.1 to 250.255.255.254250.255.255.2558,388,606
119251.0.0.0/9251.0.0.1 to 251.127.255.254251.127.255.2558,388,606
120251.128.0.0/9251.128.0.1 to 251.255.255.254251.255.255.2558,388,606
121252.0.0.0/9252.0.0.1 to 252.127.255.254252.127.255.2558,388,606
122252.128.0.0/9252.128.0.1 to 252.255.255.254252.255.255.2558,388,606
123253.0.0.0/9253.0.0.1 to 253.127.255.254253.127.255.2558,388,606
124253.128.0.0/9253.128.0.1 to 253.255.255.254253.255.255.2558,388,606
125254.0.0.0/9254.0.0.1 to 254.127.255.254254.127.255.2558,388,606
126254.128.0.0/9254.128.0.1 to 254.255.255.254254.255.255.2558,388,606
127255.0.0.0/9255.0.0.1 to 255.127.255.254255.127.255.2558,388,606
128255.128.0.0/9255.128.0.1 to 255.255.255.254255.255.255.2558,388,606

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.