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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.

Network124.64.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
124.64.0.0
Broadcast address
124.127.255.255
First usable
124.64.0.1
Last usable
124.127.255.254
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
A (default /8)
As numbers
Hex 7C400000 · Integer 2084569088 to 2088763391
Reverse DNS zones
64.124.in-addr.arpa
65.124.in-addr.arpa
66.124.in-addr.arpa
67.124.in-addr.arpa
68.124.in-addr.arpa
69.124.in-addr.arpa
70.124.in-addr.arpa
71.124.in-addr.arpa
72.124.in-addr.arpa
73.124.in-addr.arpa
74.124.in-addr.arpa
75.124.in-addr.arpa
76.124.in-addr.arpa
77.124.in-addr.arpa
78.124.in-addr.arpa
79.124.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
Address01111100.01000000.00000000.00000000124.64.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network01111100.01000000.00000000.00000000124.64.0.0
Broadcast01111100.01111111.11111111.11111111124.127.255.255
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)

124.64.0.0/10 makes 128 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1124.64.0.0/17124.64.0.1 to 124.64.127.254124.64.127.25532,766
2124.64.128.0/17124.64.128.1 to 124.64.255.254124.64.255.25532,766
3124.65.0.0/17124.65.0.1 to 124.65.127.254124.65.127.25532,766
4124.65.128.0/17124.65.128.1 to 124.65.255.254124.65.255.25532,766
5124.66.0.0/17124.66.0.1 to 124.66.127.254124.66.127.25532,766
6124.66.128.0/17124.66.128.1 to 124.66.255.254124.66.255.25532,766
7124.67.0.0/17124.67.0.1 to 124.67.127.254124.67.127.25532,766
8124.67.128.0/17124.67.128.1 to 124.67.255.254124.67.255.25532,766
9124.68.0.0/17124.68.0.1 to 124.68.127.254124.68.127.25532,766
10124.68.128.0/17124.68.128.1 to 124.68.255.254124.68.255.25532,766
11124.69.0.0/17124.69.0.1 to 124.69.127.254124.69.127.25532,766
12124.69.128.0/17124.69.128.1 to 124.69.255.254124.69.255.25532,766
13124.70.0.0/17124.70.0.1 to 124.70.127.254124.70.127.25532,766
14124.70.128.0/17124.70.128.1 to 124.70.255.254124.70.255.25532,766
15124.71.0.0/17124.71.0.1 to 124.71.127.254124.71.127.25532,766
16124.71.128.0/17124.71.128.1 to 124.71.255.254124.71.255.25532,766
17124.72.0.0/17124.72.0.1 to 124.72.127.254124.72.127.25532,766
18124.72.128.0/17124.72.128.1 to 124.72.255.254124.72.255.25532,766
19124.73.0.0/17124.73.0.1 to 124.73.127.254124.73.127.25532,766
20124.73.128.0/17124.73.128.1 to 124.73.255.254124.73.255.25532,766
21124.74.0.0/17124.74.0.1 to 124.74.127.254124.74.127.25532,766
22124.74.128.0/17124.74.128.1 to 124.74.255.254124.74.255.25532,766
23124.75.0.0/17124.75.0.1 to 124.75.127.254124.75.127.25532,766
24124.75.128.0/17124.75.128.1 to 124.75.255.254124.75.255.25532,766
25124.76.0.0/17124.76.0.1 to 124.76.127.254124.76.127.25532,766
26124.76.128.0/17124.76.128.1 to 124.76.255.254124.76.255.25532,766
27124.77.0.0/17124.77.0.1 to 124.77.127.254124.77.127.25532,766
28124.77.128.0/17124.77.128.1 to 124.77.255.254124.77.255.25532,766
29124.78.0.0/17124.78.0.1 to 124.78.127.254124.78.127.25532,766
30124.78.128.0/17124.78.128.1 to 124.78.255.254124.78.255.25532,766
31124.79.0.0/17124.79.0.1 to 124.79.127.254124.79.127.25532,766
32124.79.128.0/17124.79.128.1 to 124.79.255.254124.79.255.25532,766
33124.80.0.0/17124.80.0.1 to 124.80.127.254124.80.127.25532,766
34124.80.128.0/17124.80.128.1 to 124.80.255.254124.80.255.25532,766
35124.81.0.0/17124.81.0.1 to 124.81.127.254124.81.127.25532,766
36124.81.128.0/17124.81.128.1 to 124.81.255.254124.81.255.25532,766
37124.82.0.0/17124.82.0.1 to 124.82.127.254124.82.127.25532,766
38124.82.128.0/17124.82.128.1 to 124.82.255.254124.82.255.25532,766
39124.83.0.0/17124.83.0.1 to 124.83.127.254124.83.127.25532,766
40124.83.128.0/17124.83.128.1 to 124.83.255.254124.83.255.25532,766
41124.84.0.0/17124.84.0.1 to 124.84.127.254124.84.127.25532,766
42124.84.128.0/17124.84.128.1 to 124.84.255.254124.84.255.25532,766
43124.85.0.0/17124.85.0.1 to 124.85.127.254124.85.127.25532,766
44124.85.128.0/17124.85.128.1 to 124.85.255.254124.85.255.25532,766
45124.86.0.0/17124.86.0.1 to 124.86.127.254124.86.127.25532,766
46124.86.128.0/17124.86.128.1 to 124.86.255.254124.86.255.25532,766
47124.87.0.0/17124.87.0.1 to 124.87.127.254124.87.127.25532,766
48124.87.128.0/17124.87.128.1 to 124.87.255.254124.87.255.25532,766
49124.88.0.0/17124.88.0.1 to 124.88.127.254124.88.127.25532,766
50124.88.128.0/17124.88.128.1 to 124.88.255.254124.88.255.25532,766
51124.89.0.0/17124.89.0.1 to 124.89.127.254124.89.127.25532,766
52124.89.128.0/17124.89.128.1 to 124.89.255.254124.89.255.25532,766
53124.90.0.0/17124.90.0.1 to 124.90.127.254124.90.127.25532,766
54124.90.128.0/17124.90.128.1 to 124.90.255.254124.90.255.25532,766
55124.91.0.0/17124.91.0.1 to 124.91.127.254124.91.127.25532,766
56124.91.128.0/17124.91.128.1 to 124.91.255.254124.91.255.25532,766
57124.92.0.0/17124.92.0.1 to 124.92.127.254124.92.127.25532,766
58124.92.128.0/17124.92.128.1 to 124.92.255.254124.92.255.25532,766
59124.93.0.0/17124.93.0.1 to 124.93.127.254124.93.127.25532,766
60124.93.128.0/17124.93.128.1 to 124.93.255.254124.93.255.25532,766
61124.94.0.0/17124.94.0.1 to 124.94.127.254124.94.127.25532,766
62124.94.128.0/17124.94.128.1 to 124.94.255.254124.94.255.25532,766
63124.95.0.0/17124.95.0.1 to 124.95.127.254124.95.127.25532,766
64124.95.128.0/17124.95.128.1 to 124.95.255.254124.95.255.25532,766
65124.96.0.0/17124.96.0.1 to 124.96.127.254124.96.127.25532,766
66124.96.128.0/17124.96.128.1 to 124.96.255.254124.96.255.25532,766
67124.97.0.0/17124.97.0.1 to 124.97.127.254124.97.127.25532,766
68124.97.128.0/17124.97.128.1 to 124.97.255.254124.97.255.25532,766
69124.98.0.0/17124.98.0.1 to 124.98.127.254124.98.127.25532,766
70124.98.128.0/17124.98.128.1 to 124.98.255.254124.98.255.25532,766
71124.99.0.0/17124.99.0.1 to 124.99.127.254124.99.127.25532,766
72124.99.128.0/17124.99.128.1 to 124.99.255.254124.99.255.25532,766
73124.100.0.0/17124.100.0.1 to 124.100.127.254124.100.127.25532,766
74124.100.128.0/17124.100.128.1 to 124.100.255.254124.100.255.25532,766
75124.101.0.0/17124.101.0.1 to 124.101.127.254124.101.127.25532,766
76124.101.128.0/17124.101.128.1 to 124.101.255.254124.101.255.25532,766
77124.102.0.0/17124.102.0.1 to 124.102.127.254124.102.127.25532,766
78124.102.128.0/17124.102.128.1 to 124.102.255.254124.102.255.25532,766
79124.103.0.0/17124.103.0.1 to 124.103.127.254124.103.127.25532,766
80124.103.128.0/17124.103.128.1 to 124.103.255.254124.103.255.25532,766
81124.104.0.0/17124.104.0.1 to 124.104.127.254124.104.127.25532,766
82124.104.128.0/17124.104.128.1 to 124.104.255.254124.104.255.25532,766
83124.105.0.0/17124.105.0.1 to 124.105.127.254124.105.127.25532,766
84124.105.128.0/17124.105.128.1 to 124.105.255.254124.105.255.25532,766
85124.106.0.0/17124.106.0.1 to 124.106.127.254124.106.127.25532,766
86124.106.128.0/17124.106.128.1 to 124.106.255.254124.106.255.25532,766
87124.107.0.0/17124.107.0.1 to 124.107.127.254124.107.127.25532,766
88124.107.128.0/17124.107.128.1 to 124.107.255.254124.107.255.25532,766
89124.108.0.0/17124.108.0.1 to 124.108.127.254124.108.127.25532,766
90124.108.128.0/17124.108.128.1 to 124.108.255.254124.108.255.25532,766
91124.109.0.0/17124.109.0.1 to 124.109.127.254124.109.127.25532,766
92124.109.128.0/17124.109.128.1 to 124.109.255.254124.109.255.25532,766
93124.110.0.0/17124.110.0.1 to 124.110.127.254124.110.127.25532,766
94124.110.128.0/17124.110.128.1 to 124.110.255.254124.110.255.25532,766
95124.111.0.0/17124.111.0.1 to 124.111.127.254124.111.127.25532,766
96124.111.128.0/17124.111.128.1 to 124.111.255.254124.111.255.25532,766
97124.112.0.0/17124.112.0.1 to 124.112.127.254124.112.127.25532,766
98124.112.128.0/17124.112.128.1 to 124.112.255.254124.112.255.25532,766
99124.113.0.0/17124.113.0.1 to 124.113.127.254124.113.127.25532,766
100124.113.128.0/17124.113.128.1 to 124.113.255.254124.113.255.25532,766
101124.114.0.0/17124.114.0.1 to 124.114.127.254124.114.127.25532,766
102124.114.128.0/17124.114.128.1 to 124.114.255.254124.114.255.25532,766
103124.115.0.0/17124.115.0.1 to 124.115.127.254124.115.127.25532,766
104124.115.128.0/17124.115.128.1 to 124.115.255.254124.115.255.25532,766
105124.116.0.0/17124.116.0.1 to 124.116.127.254124.116.127.25532,766
106124.116.128.0/17124.116.128.1 to 124.116.255.254124.116.255.25532,766
107124.117.0.0/17124.117.0.1 to 124.117.127.254124.117.127.25532,766
108124.117.128.0/17124.117.128.1 to 124.117.255.254124.117.255.25532,766
109124.118.0.0/17124.118.0.1 to 124.118.127.254124.118.127.25532,766
110124.118.128.0/17124.118.128.1 to 124.118.255.254124.118.255.25532,766
111124.119.0.0/17124.119.0.1 to 124.119.127.254124.119.127.25532,766
112124.119.128.0/17124.119.128.1 to 124.119.255.254124.119.255.25532,766
113124.120.0.0/17124.120.0.1 to 124.120.127.254124.120.127.25532,766
114124.120.128.0/17124.120.128.1 to 124.120.255.254124.120.255.25532,766
115124.121.0.0/17124.121.0.1 to 124.121.127.254124.121.127.25532,766
116124.121.128.0/17124.121.128.1 to 124.121.255.254124.121.255.25532,766
117124.122.0.0/17124.122.0.1 to 124.122.127.254124.122.127.25532,766
118124.122.128.0/17124.122.128.1 to 124.122.255.254124.122.255.25532,766
119124.123.0.0/17124.123.0.1 to 124.123.127.254124.123.127.25532,766
120124.123.128.0/17124.123.128.1 to 124.123.255.254124.123.255.25532,766
121124.124.0.0/17124.124.0.1 to 124.124.127.254124.124.127.25532,766
122124.124.128.0/17124.124.128.1 to 124.124.255.254124.124.255.25532,766
123124.125.0.0/17124.125.0.1 to 124.125.127.254124.125.127.25532,766
124124.125.128.0/17124.125.128.1 to 124.125.255.254124.125.255.25532,766
125124.126.0.0/17124.126.0.1 to 124.126.127.254124.126.127.25532,766
126124.126.128.0/17124.126.128.1 to 124.126.255.254124.126.255.25532,766
127124.127.0.0/17124.127.0.1 to 124.127.127.254124.127.127.25532,766
128124.127.128.0/17124.127.128.1 to 124.127.255.254124.127.255.25532,766

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.