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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.

Network70.2.64.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
70.2.64.0
Broadcast address
70.2.95.255
First usable
70.2.64.1
Last usable
70.2.95.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
Type
Public public
Old class
A (default /8)
As numbers
Hex 46024000 · Integer 1174552576 to 1174560767
Reverse DNS zones
64.2.70.in-addr.arpa
65.2.70.in-addr.arpa
66.2.70.in-addr.arpa
67.2.70.in-addr.arpa
68.2.70.in-addr.arpa
69.2.70.in-addr.arpa
70.2.70.in-addr.arpa
71.2.70.in-addr.arpa
72.2.70.in-addr.arpa
73.2.70.in-addr.arpa
74.2.70.in-addr.arpa
75.2.70.in-addr.arpa
76.2.70.in-addr.arpa
77.2.70.in-addr.arpa
78.2.70.in-addr.arpa
79.2.70.in-addr.arpa
and 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01000110.00000010.01000000.0000000070.2.64.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network01000110.00000010.01000000.0000000070.2.64.0
Broadcast01000110.00000010.01011111.1111111170.2.95.255
Split into smaller subnets/26
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

70.2.64.0/19 makes 128 subnets of /26.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
170.2.64.0/2670.2.64.1 to 70.2.64.6270.2.64.6362
270.2.64.64/2670.2.64.65 to 70.2.64.12670.2.64.12762
370.2.64.128/2670.2.64.129 to 70.2.64.19070.2.64.19162
470.2.64.192/2670.2.64.193 to 70.2.64.25470.2.64.25562
570.2.65.0/2670.2.65.1 to 70.2.65.6270.2.65.6362
670.2.65.64/2670.2.65.65 to 70.2.65.12670.2.65.12762
770.2.65.128/2670.2.65.129 to 70.2.65.19070.2.65.19162
870.2.65.192/2670.2.65.193 to 70.2.65.25470.2.65.25562
970.2.66.0/2670.2.66.1 to 70.2.66.6270.2.66.6362
1070.2.66.64/2670.2.66.65 to 70.2.66.12670.2.66.12762
1170.2.66.128/2670.2.66.129 to 70.2.66.19070.2.66.19162
1270.2.66.192/2670.2.66.193 to 70.2.66.25470.2.66.25562
1370.2.67.0/2670.2.67.1 to 70.2.67.6270.2.67.6362
1470.2.67.64/2670.2.67.65 to 70.2.67.12670.2.67.12762
1570.2.67.128/2670.2.67.129 to 70.2.67.19070.2.67.19162
1670.2.67.192/2670.2.67.193 to 70.2.67.25470.2.67.25562
1770.2.68.0/2670.2.68.1 to 70.2.68.6270.2.68.6362
1870.2.68.64/2670.2.68.65 to 70.2.68.12670.2.68.12762
1970.2.68.128/2670.2.68.129 to 70.2.68.19070.2.68.19162
2070.2.68.192/2670.2.68.193 to 70.2.68.25470.2.68.25562
2170.2.69.0/2670.2.69.1 to 70.2.69.6270.2.69.6362
2270.2.69.64/2670.2.69.65 to 70.2.69.12670.2.69.12762
2370.2.69.128/2670.2.69.129 to 70.2.69.19070.2.69.19162
2470.2.69.192/2670.2.69.193 to 70.2.69.25470.2.69.25562
2570.2.70.0/2670.2.70.1 to 70.2.70.6270.2.70.6362
2670.2.70.64/2670.2.70.65 to 70.2.70.12670.2.70.12762
2770.2.70.128/2670.2.70.129 to 70.2.70.19070.2.70.19162
2870.2.70.192/2670.2.70.193 to 70.2.70.25470.2.70.25562
2970.2.71.0/2670.2.71.1 to 70.2.71.6270.2.71.6362
3070.2.71.64/2670.2.71.65 to 70.2.71.12670.2.71.12762
3170.2.71.128/2670.2.71.129 to 70.2.71.19070.2.71.19162
3270.2.71.192/2670.2.71.193 to 70.2.71.25470.2.71.25562
3370.2.72.0/2670.2.72.1 to 70.2.72.6270.2.72.6362
3470.2.72.64/2670.2.72.65 to 70.2.72.12670.2.72.12762
3570.2.72.128/2670.2.72.129 to 70.2.72.19070.2.72.19162
3670.2.72.192/2670.2.72.193 to 70.2.72.25470.2.72.25562
3770.2.73.0/2670.2.73.1 to 70.2.73.6270.2.73.6362
3870.2.73.64/2670.2.73.65 to 70.2.73.12670.2.73.12762
3970.2.73.128/2670.2.73.129 to 70.2.73.19070.2.73.19162
4070.2.73.192/2670.2.73.193 to 70.2.73.25470.2.73.25562
4170.2.74.0/2670.2.74.1 to 70.2.74.6270.2.74.6362
4270.2.74.64/2670.2.74.65 to 70.2.74.12670.2.74.12762
4370.2.74.128/2670.2.74.129 to 70.2.74.19070.2.74.19162
4470.2.74.192/2670.2.74.193 to 70.2.74.25470.2.74.25562
4570.2.75.0/2670.2.75.1 to 70.2.75.6270.2.75.6362
4670.2.75.64/2670.2.75.65 to 70.2.75.12670.2.75.12762
4770.2.75.128/2670.2.75.129 to 70.2.75.19070.2.75.19162
4870.2.75.192/2670.2.75.193 to 70.2.75.25470.2.75.25562
4970.2.76.0/2670.2.76.1 to 70.2.76.6270.2.76.6362
5070.2.76.64/2670.2.76.65 to 70.2.76.12670.2.76.12762
5170.2.76.128/2670.2.76.129 to 70.2.76.19070.2.76.19162
5270.2.76.192/2670.2.76.193 to 70.2.76.25470.2.76.25562
5370.2.77.0/2670.2.77.1 to 70.2.77.6270.2.77.6362
5470.2.77.64/2670.2.77.65 to 70.2.77.12670.2.77.12762
5570.2.77.128/2670.2.77.129 to 70.2.77.19070.2.77.19162
5670.2.77.192/2670.2.77.193 to 70.2.77.25470.2.77.25562
5770.2.78.0/2670.2.78.1 to 70.2.78.6270.2.78.6362
5870.2.78.64/2670.2.78.65 to 70.2.78.12670.2.78.12762
5970.2.78.128/2670.2.78.129 to 70.2.78.19070.2.78.19162
6070.2.78.192/2670.2.78.193 to 70.2.78.25470.2.78.25562
6170.2.79.0/2670.2.79.1 to 70.2.79.6270.2.79.6362
6270.2.79.64/2670.2.79.65 to 70.2.79.12670.2.79.12762
6370.2.79.128/2670.2.79.129 to 70.2.79.19070.2.79.19162
6470.2.79.192/2670.2.79.193 to 70.2.79.25470.2.79.25562
6570.2.80.0/2670.2.80.1 to 70.2.80.6270.2.80.6362
6670.2.80.64/2670.2.80.65 to 70.2.80.12670.2.80.12762
6770.2.80.128/2670.2.80.129 to 70.2.80.19070.2.80.19162
6870.2.80.192/2670.2.80.193 to 70.2.80.25470.2.80.25562
6970.2.81.0/2670.2.81.1 to 70.2.81.6270.2.81.6362
7070.2.81.64/2670.2.81.65 to 70.2.81.12670.2.81.12762
7170.2.81.128/2670.2.81.129 to 70.2.81.19070.2.81.19162
7270.2.81.192/2670.2.81.193 to 70.2.81.25470.2.81.25562
7370.2.82.0/2670.2.82.1 to 70.2.82.6270.2.82.6362
7470.2.82.64/2670.2.82.65 to 70.2.82.12670.2.82.12762
7570.2.82.128/2670.2.82.129 to 70.2.82.19070.2.82.19162
7670.2.82.192/2670.2.82.193 to 70.2.82.25470.2.82.25562
7770.2.83.0/2670.2.83.1 to 70.2.83.6270.2.83.6362
7870.2.83.64/2670.2.83.65 to 70.2.83.12670.2.83.12762
7970.2.83.128/2670.2.83.129 to 70.2.83.19070.2.83.19162
8070.2.83.192/2670.2.83.193 to 70.2.83.25470.2.83.25562
8170.2.84.0/2670.2.84.1 to 70.2.84.6270.2.84.6362
8270.2.84.64/2670.2.84.65 to 70.2.84.12670.2.84.12762
8370.2.84.128/2670.2.84.129 to 70.2.84.19070.2.84.19162
8470.2.84.192/2670.2.84.193 to 70.2.84.25470.2.84.25562
8570.2.85.0/2670.2.85.1 to 70.2.85.6270.2.85.6362
8670.2.85.64/2670.2.85.65 to 70.2.85.12670.2.85.12762
8770.2.85.128/2670.2.85.129 to 70.2.85.19070.2.85.19162
8870.2.85.192/2670.2.85.193 to 70.2.85.25470.2.85.25562
8970.2.86.0/2670.2.86.1 to 70.2.86.6270.2.86.6362
9070.2.86.64/2670.2.86.65 to 70.2.86.12670.2.86.12762
9170.2.86.128/2670.2.86.129 to 70.2.86.19070.2.86.19162
9270.2.86.192/2670.2.86.193 to 70.2.86.25470.2.86.25562
9370.2.87.0/2670.2.87.1 to 70.2.87.6270.2.87.6362
9470.2.87.64/2670.2.87.65 to 70.2.87.12670.2.87.12762
9570.2.87.128/2670.2.87.129 to 70.2.87.19070.2.87.19162
9670.2.87.192/2670.2.87.193 to 70.2.87.25470.2.87.25562
9770.2.88.0/2670.2.88.1 to 70.2.88.6270.2.88.6362
9870.2.88.64/2670.2.88.65 to 70.2.88.12670.2.88.12762
9970.2.88.128/2670.2.88.129 to 70.2.88.19070.2.88.19162
10070.2.88.192/2670.2.88.193 to 70.2.88.25470.2.88.25562
10170.2.89.0/2670.2.89.1 to 70.2.89.6270.2.89.6362
10270.2.89.64/2670.2.89.65 to 70.2.89.12670.2.89.12762
10370.2.89.128/2670.2.89.129 to 70.2.89.19070.2.89.19162
10470.2.89.192/2670.2.89.193 to 70.2.89.25470.2.89.25562
10570.2.90.0/2670.2.90.1 to 70.2.90.6270.2.90.6362
10670.2.90.64/2670.2.90.65 to 70.2.90.12670.2.90.12762
10770.2.90.128/2670.2.90.129 to 70.2.90.19070.2.90.19162
10870.2.90.192/2670.2.90.193 to 70.2.90.25470.2.90.25562
10970.2.91.0/2670.2.91.1 to 70.2.91.6270.2.91.6362
11070.2.91.64/2670.2.91.65 to 70.2.91.12670.2.91.12762
11170.2.91.128/2670.2.91.129 to 70.2.91.19070.2.91.19162
11270.2.91.192/2670.2.91.193 to 70.2.91.25470.2.91.25562
11370.2.92.0/2670.2.92.1 to 70.2.92.6270.2.92.6362
11470.2.92.64/2670.2.92.65 to 70.2.92.12670.2.92.12762
11570.2.92.128/2670.2.92.129 to 70.2.92.19070.2.92.19162
11670.2.92.192/2670.2.92.193 to 70.2.92.25470.2.92.25562
11770.2.93.0/2670.2.93.1 to 70.2.93.6270.2.93.6362
11870.2.93.64/2670.2.93.65 to 70.2.93.12670.2.93.12762
11970.2.93.128/2670.2.93.129 to 70.2.93.19070.2.93.19162
12070.2.93.192/2670.2.93.193 to 70.2.93.25470.2.93.25562
12170.2.94.0/2670.2.94.1 to 70.2.94.6270.2.94.6362
12270.2.94.64/2670.2.94.65 to 70.2.94.12670.2.94.12762
12370.2.94.128/2670.2.94.129 to 70.2.94.19070.2.94.19162
12470.2.94.192/2670.2.94.193 to 70.2.94.25470.2.94.25562
12570.2.95.0/2670.2.95.1 to 70.2.95.6270.2.95.6362
12670.2.95.64/2670.2.95.65 to 70.2.95.12670.2.95.12762
12770.2.95.128/2670.2.95.129 to 70.2.95.19070.2.95.19162
12870.2.95.192/2670.2.95.193 to 70.2.95.25470.2.95.25562

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.