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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.

Network143.64.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
143.64.0.0
Broadcast address
143.127.255.255
First usable
143.64.0.1
Last usable
143.127.255.254
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
B (default /16)
As numbers
Hex 8F400000 · Integer 2403336192 to 2407530495
Reverse DNS zones
64.143.in-addr.arpa
65.143.in-addr.arpa
66.143.in-addr.arpa
67.143.in-addr.arpa
68.143.in-addr.arpa
69.143.in-addr.arpa
70.143.in-addr.arpa
71.143.in-addr.arpa
72.143.in-addr.arpa
73.143.in-addr.arpa
74.143.in-addr.arpa
75.143.in-addr.arpa
76.143.in-addr.arpa
77.143.in-addr.arpa
78.143.in-addr.arpa
79.143.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
Address10001111.01000000.00000000.00000000143.64.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network10001111.01000000.00000000.00000000143.64.0.0
Broadcast10001111.01111111.11111111.11111111143.127.255.255
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)

143.64.0.0/10 makes 128 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1143.64.0.0/17143.64.0.1 to 143.64.127.254143.64.127.25532,766
2143.64.128.0/17143.64.128.1 to 143.64.255.254143.64.255.25532,766
3143.65.0.0/17143.65.0.1 to 143.65.127.254143.65.127.25532,766
4143.65.128.0/17143.65.128.1 to 143.65.255.254143.65.255.25532,766
5143.66.0.0/17143.66.0.1 to 143.66.127.254143.66.127.25532,766
6143.66.128.0/17143.66.128.1 to 143.66.255.254143.66.255.25532,766
7143.67.0.0/17143.67.0.1 to 143.67.127.254143.67.127.25532,766
8143.67.128.0/17143.67.128.1 to 143.67.255.254143.67.255.25532,766
9143.68.0.0/17143.68.0.1 to 143.68.127.254143.68.127.25532,766
10143.68.128.0/17143.68.128.1 to 143.68.255.254143.68.255.25532,766
11143.69.0.0/17143.69.0.1 to 143.69.127.254143.69.127.25532,766
12143.69.128.0/17143.69.128.1 to 143.69.255.254143.69.255.25532,766
13143.70.0.0/17143.70.0.1 to 143.70.127.254143.70.127.25532,766
14143.70.128.0/17143.70.128.1 to 143.70.255.254143.70.255.25532,766
15143.71.0.0/17143.71.0.1 to 143.71.127.254143.71.127.25532,766
16143.71.128.0/17143.71.128.1 to 143.71.255.254143.71.255.25532,766
17143.72.0.0/17143.72.0.1 to 143.72.127.254143.72.127.25532,766
18143.72.128.0/17143.72.128.1 to 143.72.255.254143.72.255.25532,766
19143.73.0.0/17143.73.0.1 to 143.73.127.254143.73.127.25532,766
20143.73.128.0/17143.73.128.1 to 143.73.255.254143.73.255.25532,766
21143.74.0.0/17143.74.0.1 to 143.74.127.254143.74.127.25532,766
22143.74.128.0/17143.74.128.1 to 143.74.255.254143.74.255.25532,766
23143.75.0.0/17143.75.0.1 to 143.75.127.254143.75.127.25532,766
24143.75.128.0/17143.75.128.1 to 143.75.255.254143.75.255.25532,766
25143.76.0.0/17143.76.0.1 to 143.76.127.254143.76.127.25532,766
26143.76.128.0/17143.76.128.1 to 143.76.255.254143.76.255.25532,766
27143.77.0.0/17143.77.0.1 to 143.77.127.254143.77.127.25532,766
28143.77.128.0/17143.77.128.1 to 143.77.255.254143.77.255.25532,766
29143.78.0.0/17143.78.0.1 to 143.78.127.254143.78.127.25532,766
30143.78.128.0/17143.78.128.1 to 143.78.255.254143.78.255.25532,766
31143.79.0.0/17143.79.0.1 to 143.79.127.254143.79.127.25532,766
32143.79.128.0/17143.79.128.1 to 143.79.255.254143.79.255.25532,766
33143.80.0.0/17143.80.0.1 to 143.80.127.254143.80.127.25532,766
34143.80.128.0/17143.80.128.1 to 143.80.255.254143.80.255.25532,766
35143.81.0.0/17143.81.0.1 to 143.81.127.254143.81.127.25532,766
36143.81.128.0/17143.81.128.1 to 143.81.255.254143.81.255.25532,766
37143.82.0.0/17143.82.0.1 to 143.82.127.254143.82.127.25532,766
38143.82.128.0/17143.82.128.1 to 143.82.255.254143.82.255.25532,766
39143.83.0.0/17143.83.0.1 to 143.83.127.254143.83.127.25532,766
40143.83.128.0/17143.83.128.1 to 143.83.255.254143.83.255.25532,766
41143.84.0.0/17143.84.0.1 to 143.84.127.254143.84.127.25532,766
42143.84.128.0/17143.84.128.1 to 143.84.255.254143.84.255.25532,766
43143.85.0.0/17143.85.0.1 to 143.85.127.254143.85.127.25532,766
44143.85.128.0/17143.85.128.1 to 143.85.255.254143.85.255.25532,766
45143.86.0.0/17143.86.0.1 to 143.86.127.254143.86.127.25532,766
46143.86.128.0/17143.86.128.1 to 143.86.255.254143.86.255.25532,766
47143.87.0.0/17143.87.0.1 to 143.87.127.254143.87.127.25532,766
48143.87.128.0/17143.87.128.1 to 143.87.255.254143.87.255.25532,766
49143.88.0.0/17143.88.0.1 to 143.88.127.254143.88.127.25532,766
50143.88.128.0/17143.88.128.1 to 143.88.255.254143.88.255.25532,766
51143.89.0.0/17143.89.0.1 to 143.89.127.254143.89.127.25532,766
52143.89.128.0/17143.89.128.1 to 143.89.255.254143.89.255.25532,766
53143.90.0.0/17143.90.0.1 to 143.90.127.254143.90.127.25532,766
54143.90.128.0/17143.90.128.1 to 143.90.255.254143.90.255.25532,766
55143.91.0.0/17143.91.0.1 to 143.91.127.254143.91.127.25532,766
56143.91.128.0/17143.91.128.1 to 143.91.255.254143.91.255.25532,766
57143.92.0.0/17143.92.0.1 to 143.92.127.254143.92.127.25532,766
58143.92.128.0/17143.92.128.1 to 143.92.255.254143.92.255.25532,766
59143.93.0.0/17143.93.0.1 to 143.93.127.254143.93.127.25532,766
60143.93.128.0/17143.93.128.1 to 143.93.255.254143.93.255.25532,766
61143.94.0.0/17143.94.0.1 to 143.94.127.254143.94.127.25532,766
62143.94.128.0/17143.94.128.1 to 143.94.255.254143.94.255.25532,766
63143.95.0.0/17143.95.0.1 to 143.95.127.254143.95.127.25532,766
64143.95.128.0/17143.95.128.1 to 143.95.255.254143.95.255.25532,766
65143.96.0.0/17143.96.0.1 to 143.96.127.254143.96.127.25532,766
66143.96.128.0/17143.96.128.1 to 143.96.255.254143.96.255.25532,766
67143.97.0.0/17143.97.0.1 to 143.97.127.254143.97.127.25532,766
68143.97.128.0/17143.97.128.1 to 143.97.255.254143.97.255.25532,766
69143.98.0.0/17143.98.0.1 to 143.98.127.254143.98.127.25532,766
70143.98.128.0/17143.98.128.1 to 143.98.255.254143.98.255.25532,766
71143.99.0.0/17143.99.0.1 to 143.99.127.254143.99.127.25532,766
72143.99.128.0/17143.99.128.1 to 143.99.255.254143.99.255.25532,766
73143.100.0.0/17143.100.0.1 to 143.100.127.254143.100.127.25532,766
74143.100.128.0/17143.100.128.1 to 143.100.255.254143.100.255.25532,766
75143.101.0.0/17143.101.0.1 to 143.101.127.254143.101.127.25532,766
76143.101.128.0/17143.101.128.1 to 143.101.255.254143.101.255.25532,766
77143.102.0.0/17143.102.0.1 to 143.102.127.254143.102.127.25532,766
78143.102.128.0/17143.102.128.1 to 143.102.255.254143.102.255.25532,766
79143.103.0.0/17143.103.0.1 to 143.103.127.254143.103.127.25532,766
80143.103.128.0/17143.103.128.1 to 143.103.255.254143.103.255.25532,766
81143.104.0.0/17143.104.0.1 to 143.104.127.254143.104.127.25532,766
82143.104.128.0/17143.104.128.1 to 143.104.255.254143.104.255.25532,766
83143.105.0.0/17143.105.0.1 to 143.105.127.254143.105.127.25532,766
84143.105.128.0/17143.105.128.1 to 143.105.255.254143.105.255.25532,766
85143.106.0.0/17143.106.0.1 to 143.106.127.254143.106.127.25532,766
86143.106.128.0/17143.106.128.1 to 143.106.255.254143.106.255.25532,766
87143.107.0.0/17143.107.0.1 to 143.107.127.254143.107.127.25532,766
88143.107.128.0/17143.107.128.1 to 143.107.255.254143.107.255.25532,766
89143.108.0.0/17143.108.0.1 to 143.108.127.254143.108.127.25532,766
90143.108.128.0/17143.108.128.1 to 143.108.255.254143.108.255.25532,766
91143.109.0.0/17143.109.0.1 to 143.109.127.254143.109.127.25532,766
92143.109.128.0/17143.109.128.1 to 143.109.255.254143.109.255.25532,766
93143.110.0.0/17143.110.0.1 to 143.110.127.254143.110.127.25532,766
94143.110.128.0/17143.110.128.1 to 143.110.255.254143.110.255.25532,766
95143.111.0.0/17143.111.0.1 to 143.111.127.254143.111.127.25532,766
96143.111.128.0/17143.111.128.1 to 143.111.255.254143.111.255.25532,766
97143.112.0.0/17143.112.0.1 to 143.112.127.254143.112.127.25532,766
98143.112.128.0/17143.112.128.1 to 143.112.255.254143.112.255.25532,766
99143.113.0.0/17143.113.0.1 to 143.113.127.254143.113.127.25532,766
100143.113.128.0/17143.113.128.1 to 143.113.255.254143.113.255.25532,766
101143.114.0.0/17143.114.0.1 to 143.114.127.254143.114.127.25532,766
102143.114.128.0/17143.114.128.1 to 143.114.255.254143.114.255.25532,766
103143.115.0.0/17143.115.0.1 to 143.115.127.254143.115.127.25532,766
104143.115.128.0/17143.115.128.1 to 143.115.255.254143.115.255.25532,766
105143.116.0.0/17143.116.0.1 to 143.116.127.254143.116.127.25532,766
106143.116.128.0/17143.116.128.1 to 143.116.255.254143.116.255.25532,766
107143.117.0.0/17143.117.0.1 to 143.117.127.254143.117.127.25532,766
108143.117.128.0/17143.117.128.1 to 143.117.255.254143.117.255.25532,766
109143.118.0.0/17143.118.0.1 to 143.118.127.254143.118.127.25532,766
110143.118.128.0/17143.118.128.1 to 143.118.255.254143.118.255.25532,766
111143.119.0.0/17143.119.0.1 to 143.119.127.254143.119.127.25532,766
112143.119.128.0/17143.119.128.1 to 143.119.255.254143.119.255.25532,766
113143.120.0.0/17143.120.0.1 to 143.120.127.254143.120.127.25532,766
114143.120.128.0/17143.120.128.1 to 143.120.255.254143.120.255.25532,766
115143.121.0.0/17143.121.0.1 to 143.121.127.254143.121.127.25532,766
116143.121.128.0/17143.121.128.1 to 143.121.255.254143.121.255.25532,766
117143.122.0.0/17143.122.0.1 to 143.122.127.254143.122.127.25532,766
118143.122.128.0/17143.122.128.1 to 143.122.255.254143.122.255.25532,766
119143.123.0.0/17143.123.0.1 to 143.123.127.254143.123.127.25532,766
120143.123.128.0/17143.123.128.1 to 143.123.255.254143.123.255.25532,766
121143.124.0.0/17143.124.0.1 to 143.124.127.254143.124.127.25532,766
122143.124.128.0/17143.124.128.1 to 143.124.255.254143.124.255.25532,766
123143.125.0.0/17143.125.0.1 to 143.125.127.254143.125.127.25532,766
124143.125.128.0/17143.125.128.1 to 143.125.255.254143.125.255.25532,766
125143.126.0.0/17143.126.0.1 to 143.126.127.254143.126.127.25532,766
126143.126.128.0/17143.126.128.1 to 143.126.255.254143.126.255.25532,766
127143.127.0.0/17143.127.0.1 to 143.127.127.254143.127.127.25532,766
128143.127.128.0/17143.127.128.1 to 143.127.255.254143.127.255.25532,766

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.