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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.

Network147.34.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
147.34.0.0
Broadcast address
147.35.255.255
First usable
147.34.0.1
Last usable
147.35.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Public public
Old class
B (default /16)
As numbers
Hex 93220000 · Integer 2468478976 to 2468610047
Reverse DNS zones
34.147.in-addr.arpa
35.147.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10010011.00100010.00000000.00000000147.34.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network10010011.00100010.00000000.00000000147.34.0.0
Broadcast10010011.00100011.11111111.11111111147.35.255.255
Split into smaller subnets/21
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

147.34.0.0/15 makes 64 subnets of /21.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1147.34.0.0/21147.34.0.1 to 147.34.7.254147.34.7.2552,046
2147.34.8.0/21147.34.8.1 to 147.34.15.254147.34.15.2552,046
3147.34.16.0/21147.34.16.1 to 147.34.23.254147.34.23.2552,046
4147.34.24.0/21147.34.24.1 to 147.34.31.254147.34.31.2552,046
5147.34.32.0/21147.34.32.1 to 147.34.39.254147.34.39.2552,046
6147.34.40.0/21147.34.40.1 to 147.34.47.254147.34.47.2552,046
7147.34.48.0/21147.34.48.1 to 147.34.55.254147.34.55.2552,046
8147.34.56.0/21147.34.56.1 to 147.34.63.254147.34.63.2552,046
9147.34.64.0/21147.34.64.1 to 147.34.71.254147.34.71.2552,046
10147.34.72.0/21147.34.72.1 to 147.34.79.254147.34.79.2552,046
11147.34.80.0/21147.34.80.1 to 147.34.87.254147.34.87.2552,046
12147.34.88.0/21147.34.88.1 to 147.34.95.254147.34.95.2552,046
13147.34.96.0/21147.34.96.1 to 147.34.103.254147.34.103.2552,046
14147.34.104.0/21147.34.104.1 to 147.34.111.254147.34.111.2552,046
15147.34.112.0/21147.34.112.1 to 147.34.119.254147.34.119.2552,046
16147.34.120.0/21147.34.120.1 to 147.34.127.254147.34.127.2552,046
17147.34.128.0/21147.34.128.1 to 147.34.135.254147.34.135.2552,046
18147.34.136.0/21147.34.136.1 to 147.34.143.254147.34.143.2552,046
19147.34.144.0/21147.34.144.1 to 147.34.151.254147.34.151.2552,046
20147.34.152.0/21147.34.152.1 to 147.34.159.254147.34.159.2552,046
21147.34.160.0/21147.34.160.1 to 147.34.167.254147.34.167.2552,046
22147.34.168.0/21147.34.168.1 to 147.34.175.254147.34.175.2552,046
23147.34.176.0/21147.34.176.1 to 147.34.183.254147.34.183.2552,046
24147.34.184.0/21147.34.184.1 to 147.34.191.254147.34.191.2552,046
25147.34.192.0/21147.34.192.1 to 147.34.199.254147.34.199.2552,046
26147.34.200.0/21147.34.200.1 to 147.34.207.254147.34.207.2552,046
27147.34.208.0/21147.34.208.1 to 147.34.215.254147.34.215.2552,046
28147.34.216.0/21147.34.216.1 to 147.34.223.254147.34.223.2552,046
29147.34.224.0/21147.34.224.1 to 147.34.231.254147.34.231.2552,046
30147.34.232.0/21147.34.232.1 to 147.34.239.254147.34.239.2552,046
31147.34.240.0/21147.34.240.1 to 147.34.247.254147.34.247.2552,046
32147.34.248.0/21147.34.248.1 to 147.34.255.254147.34.255.2552,046
33147.35.0.0/21147.35.0.1 to 147.35.7.254147.35.7.2552,046
34147.35.8.0/21147.35.8.1 to 147.35.15.254147.35.15.2552,046
35147.35.16.0/21147.35.16.1 to 147.35.23.254147.35.23.2552,046
36147.35.24.0/21147.35.24.1 to 147.35.31.254147.35.31.2552,046
37147.35.32.0/21147.35.32.1 to 147.35.39.254147.35.39.2552,046
38147.35.40.0/21147.35.40.1 to 147.35.47.254147.35.47.2552,046
39147.35.48.0/21147.35.48.1 to 147.35.55.254147.35.55.2552,046
40147.35.56.0/21147.35.56.1 to 147.35.63.254147.35.63.2552,046
41147.35.64.0/21147.35.64.1 to 147.35.71.254147.35.71.2552,046
42147.35.72.0/21147.35.72.1 to 147.35.79.254147.35.79.2552,046
43147.35.80.0/21147.35.80.1 to 147.35.87.254147.35.87.2552,046
44147.35.88.0/21147.35.88.1 to 147.35.95.254147.35.95.2552,046
45147.35.96.0/21147.35.96.1 to 147.35.103.254147.35.103.2552,046
46147.35.104.0/21147.35.104.1 to 147.35.111.254147.35.111.2552,046
47147.35.112.0/21147.35.112.1 to 147.35.119.254147.35.119.2552,046
48147.35.120.0/21147.35.120.1 to 147.35.127.254147.35.127.2552,046
49147.35.128.0/21147.35.128.1 to 147.35.135.254147.35.135.2552,046
50147.35.136.0/21147.35.136.1 to 147.35.143.254147.35.143.2552,046
51147.35.144.0/21147.35.144.1 to 147.35.151.254147.35.151.2552,046
52147.35.152.0/21147.35.152.1 to 147.35.159.254147.35.159.2552,046
53147.35.160.0/21147.35.160.1 to 147.35.167.254147.35.167.2552,046
54147.35.168.0/21147.35.168.1 to 147.35.175.254147.35.175.2552,046
55147.35.176.0/21147.35.176.1 to 147.35.183.254147.35.183.2552,046
56147.35.184.0/21147.35.184.1 to 147.35.191.254147.35.191.2552,046
57147.35.192.0/21147.35.192.1 to 147.35.199.254147.35.199.2552,046
58147.35.200.0/21147.35.200.1 to 147.35.207.254147.35.207.2552,046
59147.35.208.0/21147.35.208.1 to 147.35.215.254147.35.215.2552,046
60147.35.216.0/21147.35.216.1 to 147.35.223.254147.35.223.2552,046
61147.35.224.0/21147.35.224.1 to 147.35.231.254147.35.231.2552,046
62147.35.232.0/21147.35.232.1 to 147.35.239.254147.35.239.2552,046
63147.35.240.0/21147.35.240.1 to 147.35.247.254147.35.247.2552,046
64147.35.248.0/21147.35.248.1 to 147.35.255.254147.35.255.2552,046

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.