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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.

Network147.40.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
147.40.0.0
Broadcast address
147.41.255.255
First usable
147.40.0.1
Last usable
147.41.255.254
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 93280000 · Integer 2468872192 to 2469003263
Reverse DNS zones
40.147.in-addr.arpa
41.147.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
Address10010011.00101000.00000000.00000000147.40.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network10010011.00101000.00000000.00000000147.40.0.0
Broadcast10010011.00101001.11111111.11111111147.41.255.255
Split into smaller subnets/22
/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)

147.40.0.0/15 makes 128 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1147.40.0.0/22147.40.0.1 to 147.40.3.254147.40.3.2551,022
2147.40.4.0/22147.40.4.1 to 147.40.7.254147.40.7.2551,022
3147.40.8.0/22147.40.8.1 to 147.40.11.254147.40.11.2551,022
4147.40.12.0/22147.40.12.1 to 147.40.15.254147.40.15.2551,022
5147.40.16.0/22147.40.16.1 to 147.40.19.254147.40.19.2551,022
6147.40.20.0/22147.40.20.1 to 147.40.23.254147.40.23.2551,022
7147.40.24.0/22147.40.24.1 to 147.40.27.254147.40.27.2551,022
8147.40.28.0/22147.40.28.1 to 147.40.31.254147.40.31.2551,022
9147.40.32.0/22147.40.32.1 to 147.40.35.254147.40.35.2551,022
10147.40.36.0/22147.40.36.1 to 147.40.39.254147.40.39.2551,022
11147.40.40.0/22147.40.40.1 to 147.40.43.254147.40.43.2551,022
12147.40.44.0/22147.40.44.1 to 147.40.47.254147.40.47.2551,022
13147.40.48.0/22147.40.48.1 to 147.40.51.254147.40.51.2551,022
14147.40.52.0/22147.40.52.1 to 147.40.55.254147.40.55.2551,022
15147.40.56.0/22147.40.56.1 to 147.40.59.254147.40.59.2551,022
16147.40.60.0/22147.40.60.1 to 147.40.63.254147.40.63.2551,022
17147.40.64.0/22147.40.64.1 to 147.40.67.254147.40.67.2551,022
18147.40.68.0/22147.40.68.1 to 147.40.71.254147.40.71.2551,022
19147.40.72.0/22147.40.72.1 to 147.40.75.254147.40.75.2551,022
20147.40.76.0/22147.40.76.1 to 147.40.79.254147.40.79.2551,022
21147.40.80.0/22147.40.80.1 to 147.40.83.254147.40.83.2551,022
22147.40.84.0/22147.40.84.1 to 147.40.87.254147.40.87.2551,022
23147.40.88.0/22147.40.88.1 to 147.40.91.254147.40.91.2551,022
24147.40.92.0/22147.40.92.1 to 147.40.95.254147.40.95.2551,022
25147.40.96.0/22147.40.96.1 to 147.40.99.254147.40.99.2551,022
26147.40.100.0/22147.40.100.1 to 147.40.103.254147.40.103.2551,022
27147.40.104.0/22147.40.104.1 to 147.40.107.254147.40.107.2551,022
28147.40.108.0/22147.40.108.1 to 147.40.111.254147.40.111.2551,022
29147.40.112.0/22147.40.112.1 to 147.40.115.254147.40.115.2551,022
30147.40.116.0/22147.40.116.1 to 147.40.119.254147.40.119.2551,022
31147.40.120.0/22147.40.120.1 to 147.40.123.254147.40.123.2551,022
32147.40.124.0/22147.40.124.1 to 147.40.127.254147.40.127.2551,022
33147.40.128.0/22147.40.128.1 to 147.40.131.254147.40.131.2551,022
34147.40.132.0/22147.40.132.1 to 147.40.135.254147.40.135.2551,022
35147.40.136.0/22147.40.136.1 to 147.40.139.254147.40.139.2551,022
36147.40.140.0/22147.40.140.1 to 147.40.143.254147.40.143.2551,022
37147.40.144.0/22147.40.144.1 to 147.40.147.254147.40.147.2551,022
38147.40.148.0/22147.40.148.1 to 147.40.151.254147.40.151.2551,022
39147.40.152.0/22147.40.152.1 to 147.40.155.254147.40.155.2551,022
40147.40.156.0/22147.40.156.1 to 147.40.159.254147.40.159.2551,022
41147.40.160.0/22147.40.160.1 to 147.40.163.254147.40.163.2551,022
42147.40.164.0/22147.40.164.1 to 147.40.167.254147.40.167.2551,022
43147.40.168.0/22147.40.168.1 to 147.40.171.254147.40.171.2551,022
44147.40.172.0/22147.40.172.1 to 147.40.175.254147.40.175.2551,022
45147.40.176.0/22147.40.176.1 to 147.40.179.254147.40.179.2551,022
46147.40.180.0/22147.40.180.1 to 147.40.183.254147.40.183.2551,022
47147.40.184.0/22147.40.184.1 to 147.40.187.254147.40.187.2551,022
48147.40.188.0/22147.40.188.1 to 147.40.191.254147.40.191.2551,022
49147.40.192.0/22147.40.192.1 to 147.40.195.254147.40.195.2551,022
50147.40.196.0/22147.40.196.1 to 147.40.199.254147.40.199.2551,022
51147.40.200.0/22147.40.200.1 to 147.40.203.254147.40.203.2551,022
52147.40.204.0/22147.40.204.1 to 147.40.207.254147.40.207.2551,022
53147.40.208.0/22147.40.208.1 to 147.40.211.254147.40.211.2551,022
54147.40.212.0/22147.40.212.1 to 147.40.215.254147.40.215.2551,022
55147.40.216.0/22147.40.216.1 to 147.40.219.254147.40.219.2551,022
56147.40.220.0/22147.40.220.1 to 147.40.223.254147.40.223.2551,022
57147.40.224.0/22147.40.224.1 to 147.40.227.254147.40.227.2551,022
58147.40.228.0/22147.40.228.1 to 147.40.231.254147.40.231.2551,022
59147.40.232.0/22147.40.232.1 to 147.40.235.254147.40.235.2551,022
60147.40.236.0/22147.40.236.1 to 147.40.239.254147.40.239.2551,022
61147.40.240.0/22147.40.240.1 to 147.40.243.254147.40.243.2551,022
62147.40.244.0/22147.40.244.1 to 147.40.247.254147.40.247.2551,022
63147.40.248.0/22147.40.248.1 to 147.40.251.254147.40.251.2551,022
64147.40.252.0/22147.40.252.1 to 147.40.255.254147.40.255.2551,022
65147.41.0.0/22147.41.0.1 to 147.41.3.254147.41.3.2551,022
66147.41.4.0/22147.41.4.1 to 147.41.7.254147.41.7.2551,022
67147.41.8.0/22147.41.8.1 to 147.41.11.254147.41.11.2551,022
68147.41.12.0/22147.41.12.1 to 147.41.15.254147.41.15.2551,022
69147.41.16.0/22147.41.16.1 to 147.41.19.254147.41.19.2551,022
70147.41.20.0/22147.41.20.1 to 147.41.23.254147.41.23.2551,022
71147.41.24.0/22147.41.24.1 to 147.41.27.254147.41.27.2551,022
72147.41.28.0/22147.41.28.1 to 147.41.31.254147.41.31.2551,022
73147.41.32.0/22147.41.32.1 to 147.41.35.254147.41.35.2551,022
74147.41.36.0/22147.41.36.1 to 147.41.39.254147.41.39.2551,022
75147.41.40.0/22147.41.40.1 to 147.41.43.254147.41.43.2551,022
76147.41.44.0/22147.41.44.1 to 147.41.47.254147.41.47.2551,022
77147.41.48.0/22147.41.48.1 to 147.41.51.254147.41.51.2551,022
78147.41.52.0/22147.41.52.1 to 147.41.55.254147.41.55.2551,022
79147.41.56.0/22147.41.56.1 to 147.41.59.254147.41.59.2551,022
80147.41.60.0/22147.41.60.1 to 147.41.63.254147.41.63.2551,022
81147.41.64.0/22147.41.64.1 to 147.41.67.254147.41.67.2551,022
82147.41.68.0/22147.41.68.1 to 147.41.71.254147.41.71.2551,022
83147.41.72.0/22147.41.72.1 to 147.41.75.254147.41.75.2551,022
84147.41.76.0/22147.41.76.1 to 147.41.79.254147.41.79.2551,022
85147.41.80.0/22147.41.80.1 to 147.41.83.254147.41.83.2551,022
86147.41.84.0/22147.41.84.1 to 147.41.87.254147.41.87.2551,022
87147.41.88.0/22147.41.88.1 to 147.41.91.254147.41.91.2551,022
88147.41.92.0/22147.41.92.1 to 147.41.95.254147.41.95.2551,022
89147.41.96.0/22147.41.96.1 to 147.41.99.254147.41.99.2551,022
90147.41.100.0/22147.41.100.1 to 147.41.103.254147.41.103.2551,022
91147.41.104.0/22147.41.104.1 to 147.41.107.254147.41.107.2551,022
92147.41.108.0/22147.41.108.1 to 147.41.111.254147.41.111.2551,022
93147.41.112.0/22147.41.112.1 to 147.41.115.254147.41.115.2551,022
94147.41.116.0/22147.41.116.1 to 147.41.119.254147.41.119.2551,022
95147.41.120.0/22147.41.120.1 to 147.41.123.254147.41.123.2551,022
96147.41.124.0/22147.41.124.1 to 147.41.127.254147.41.127.2551,022
97147.41.128.0/22147.41.128.1 to 147.41.131.254147.41.131.2551,022
98147.41.132.0/22147.41.132.1 to 147.41.135.254147.41.135.2551,022
99147.41.136.0/22147.41.136.1 to 147.41.139.254147.41.139.2551,022
100147.41.140.0/22147.41.140.1 to 147.41.143.254147.41.143.2551,022
101147.41.144.0/22147.41.144.1 to 147.41.147.254147.41.147.2551,022
102147.41.148.0/22147.41.148.1 to 147.41.151.254147.41.151.2551,022
103147.41.152.0/22147.41.152.1 to 147.41.155.254147.41.155.2551,022
104147.41.156.0/22147.41.156.1 to 147.41.159.254147.41.159.2551,022
105147.41.160.0/22147.41.160.1 to 147.41.163.254147.41.163.2551,022
106147.41.164.0/22147.41.164.1 to 147.41.167.254147.41.167.2551,022
107147.41.168.0/22147.41.168.1 to 147.41.171.254147.41.171.2551,022
108147.41.172.0/22147.41.172.1 to 147.41.175.254147.41.175.2551,022
109147.41.176.0/22147.41.176.1 to 147.41.179.254147.41.179.2551,022
110147.41.180.0/22147.41.180.1 to 147.41.183.254147.41.183.2551,022
111147.41.184.0/22147.41.184.1 to 147.41.187.254147.41.187.2551,022
112147.41.188.0/22147.41.188.1 to 147.41.191.254147.41.191.2551,022
113147.41.192.0/22147.41.192.1 to 147.41.195.254147.41.195.2551,022
114147.41.196.0/22147.41.196.1 to 147.41.199.254147.41.199.2551,022
115147.41.200.0/22147.41.200.1 to 147.41.203.254147.41.203.2551,022
116147.41.204.0/22147.41.204.1 to 147.41.207.254147.41.207.2551,022
117147.41.208.0/22147.41.208.1 to 147.41.211.254147.41.211.2551,022
118147.41.212.0/22147.41.212.1 to 147.41.215.254147.41.215.2551,022
119147.41.216.0/22147.41.216.1 to 147.41.219.254147.41.219.2551,022
120147.41.220.0/22147.41.220.1 to 147.41.223.254147.41.223.2551,022
121147.41.224.0/22147.41.224.1 to 147.41.227.254147.41.227.2551,022
122147.41.228.0/22147.41.228.1 to 147.41.231.254147.41.231.2551,022
123147.41.232.0/22147.41.232.1 to 147.41.235.254147.41.235.2551,022
124147.41.236.0/22147.41.236.1 to 147.41.239.254147.41.239.2551,022
125147.41.240.0/22147.41.240.1 to 147.41.243.254147.41.243.2551,022
126147.41.244.0/22147.41.244.1 to 147.41.247.254147.41.247.2551,022
127147.41.248.0/22147.41.248.1 to 147.41.251.254147.41.251.2551,022
128147.41.252.0/22147.41.252.1 to 147.41.255.254147.41.255.2551,022

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.