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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.

Network148.0.0.0/7
Usable hosts33,554,430
Subnet mask254.0.0.0
Addresses33,554,432
Network address
148.0.0.0
Broadcast address
149.255.255.255
First usable
148.0.0.1
Last usable
149.255.255.254
Usable hosts
33,554,430 (33,554,432 less the network and broadcast addresses)
Subnet mask
254.0.0.0
Wildcard mask
1.255.255.255 (Cisco ACLs, OSPF)
Prefix length
/7
Type
Public public
Old class
B (default /16)
As numbers
Hex 94000000 · Integer 2483027968 to 2516582399
Reverse DNS zones
148.in-addr.arpa
149.in-addr.arpa
/7 is not on a 8-bit boundary, so it takes 2 /8 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10010100.00000000.00000000.00000000148.0.0.0
Subnet mask11111110.00000000.00000000.00000000254.0.0.0
Network10010100.00000000.00000000.00000000148.0.0.0
Broadcast10010101.11111111.11111111.11111111149.255.255.255
Split into smaller subnets/14
/8 (2)/9 (4)/10 (8)/11 (16)/12 (32)/13 (64)/14 (128)/15 (256)/16 (512)/17 (1,024)/18 (2,048)/19 (4,096)

148.0.0.0/7 makes 128 subnets of /14.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1148.0.0.0/14148.0.0.1 to 148.3.255.254148.3.255.255262,142
2148.4.0.0/14148.4.0.1 to 148.7.255.254148.7.255.255262,142
3148.8.0.0/14148.8.0.1 to 148.11.255.254148.11.255.255262,142
4148.12.0.0/14148.12.0.1 to 148.15.255.254148.15.255.255262,142
5148.16.0.0/14148.16.0.1 to 148.19.255.254148.19.255.255262,142
6148.20.0.0/14148.20.0.1 to 148.23.255.254148.23.255.255262,142
7148.24.0.0/14148.24.0.1 to 148.27.255.254148.27.255.255262,142
8148.28.0.0/14148.28.0.1 to 148.31.255.254148.31.255.255262,142
9148.32.0.0/14148.32.0.1 to 148.35.255.254148.35.255.255262,142
10148.36.0.0/14148.36.0.1 to 148.39.255.254148.39.255.255262,142
11148.40.0.0/14148.40.0.1 to 148.43.255.254148.43.255.255262,142
12148.44.0.0/14148.44.0.1 to 148.47.255.254148.47.255.255262,142
13148.48.0.0/14148.48.0.1 to 148.51.255.254148.51.255.255262,142
14148.52.0.0/14148.52.0.1 to 148.55.255.254148.55.255.255262,142
15148.56.0.0/14148.56.0.1 to 148.59.255.254148.59.255.255262,142
16148.60.0.0/14148.60.0.1 to 148.63.255.254148.63.255.255262,142
17148.64.0.0/14148.64.0.1 to 148.67.255.254148.67.255.255262,142
18148.68.0.0/14148.68.0.1 to 148.71.255.254148.71.255.255262,142
19148.72.0.0/14148.72.0.1 to 148.75.255.254148.75.255.255262,142
20148.76.0.0/14148.76.0.1 to 148.79.255.254148.79.255.255262,142
21148.80.0.0/14148.80.0.1 to 148.83.255.254148.83.255.255262,142
22148.84.0.0/14148.84.0.1 to 148.87.255.254148.87.255.255262,142
23148.88.0.0/14148.88.0.1 to 148.91.255.254148.91.255.255262,142
24148.92.0.0/14148.92.0.1 to 148.95.255.254148.95.255.255262,142
25148.96.0.0/14148.96.0.1 to 148.99.255.254148.99.255.255262,142
26148.100.0.0/14148.100.0.1 to 148.103.255.254148.103.255.255262,142
27148.104.0.0/14148.104.0.1 to 148.107.255.254148.107.255.255262,142
28148.108.0.0/14148.108.0.1 to 148.111.255.254148.111.255.255262,142
29148.112.0.0/14148.112.0.1 to 148.115.255.254148.115.255.255262,142
30148.116.0.0/14148.116.0.1 to 148.119.255.254148.119.255.255262,142
31148.120.0.0/14148.120.0.1 to 148.123.255.254148.123.255.255262,142
32148.124.0.0/14148.124.0.1 to 148.127.255.254148.127.255.255262,142
33148.128.0.0/14148.128.0.1 to 148.131.255.254148.131.255.255262,142
34148.132.0.0/14148.132.0.1 to 148.135.255.254148.135.255.255262,142
35148.136.0.0/14148.136.0.1 to 148.139.255.254148.139.255.255262,142
36148.140.0.0/14148.140.0.1 to 148.143.255.254148.143.255.255262,142
37148.144.0.0/14148.144.0.1 to 148.147.255.254148.147.255.255262,142
38148.148.0.0/14148.148.0.1 to 148.151.255.254148.151.255.255262,142
39148.152.0.0/14148.152.0.1 to 148.155.255.254148.155.255.255262,142
40148.156.0.0/14148.156.0.1 to 148.159.255.254148.159.255.255262,142
41148.160.0.0/14148.160.0.1 to 148.163.255.254148.163.255.255262,142
42148.164.0.0/14148.164.0.1 to 148.167.255.254148.167.255.255262,142
43148.168.0.0/14148.168.0.1 to 148.171.255.254148.171.255.255262,142
44148.172.0.0/14148.172.0.1 to 148.175.255.254148.175.255.255262,142
45148.176.0.0/14148.176.0.1 to 148.179.255.254148.179.255.255262,142
46148.180.0.0/14148.180.0.1 to 148.183.255.254148.183.255.255262,142
47148.184.0.0/14148.184.0.1 to 148.187.255.254148.187.255.255262,142
48148.188.0.0/14148.188.0.1 to 148.191.255.254148.191.255.255262,142
49148.192.0.0/14148.192.0.1 to 148.195.255.254148.195.255.255262,142
50148.196.0.0/14148.196.0.1 to 148.199.255.254148.199.255.255262,142
51148.200.0.0/14148.200.0.1 to 148.203.255.254148.203.255.255262,142
52148.204.0.0/14148.204.0.1 to 148.207.255.254148.207.255.255262,142
53148.208.0.0/14148.208.0.1 to 148.211.255.254148.211.255.255262,142
54148.212.0.0/14148.212.0.1 to 148.215.255.254148.215.255.255262,142
55148.216.0.0/14148.216.0.1 to 148.219.255.254148.219.255.255262,142
56148.220.0.0/14148.220.0.1 to 148.223.255.254148.223.255.255262,142
57148.224.0.0/14148.224.0.1 to 148.227.255.254148.227.255.255262,142
58148.228.0.0/14148.228.0.1 to 148.231.255.254148.231.255.255262,142
59148.232.0.0/14148.232.0.1 to 148.235.255.254148.235.255.255262,142
60148.236.0.0/14148.236.0.1 to 148.239.255.254148.239.255.255262,142
61148.240.0.0/14148.240.0.1 to 148.243.255.254148.243.255.255262,142
62148.244.0.0/14148.244.0.1 to 148.247.255.254148.247.255.255262,142
63148.248.0.0/14148.248.0.1 to 148.251.255.254148.251.255.255262,142
64148.252.0.0/14148.252.0.1 to 148.255.255.254148.255.255.255262,142
65149.0.0.0/14149.0.0.1 to 149.3.255.254149.3.255.255262,142
66149.4.0.0/14149.4.0.1 to 149.7.255.254149.7.255.255262,142
67149.8.0.0/14149.8.0.1 to 149.11.255.254149.11.255.255262,142
68149.12.0.0/14149.12.0.1 to 149.15.255.254149.15.255.255262,142
69149.16.0.0/14149.16.0.1 to 149.19.255.254149.19.255.255262,142
70149.20.0.0/14149.20.0.1 to 149.23.255.254149.23.255.255262,142
71149.24.0.0/14149.24.0.1 to 149.27.255.254149.27.255.255262,142
72149.28.0.0/14149.28.0.1 to 149.31.255.254149.31.255.255262,142
73149.32.0.0/14149.32.0.1 to 149.35.255.254149.35.255.255262,142
74149.36.0.0/14149.36.0.1 to 149.39.255.254149.39.255.255262,142
75149.40.0.0/14149.40.0.1 to 149.43.255.254149.43.255.255262,142
76149.44.0.0/14149.44.0.1 to 149.47.255.254149.47.255.255262,142
77149.48.0.0/14149.48.0.1 to 149.51.255.254149.51.255.255262,142
78149.52.0.0/14149.52.0.1 to 149.55.255.254149.55.255.255262,142
79149.56.0.0/14149.56.0.1 to 149.59.255.254149.59.255.255262,142
80149.60.0.0/14149.60.0.1 to 149.63.255.254149.63.255.255262,142
81149.64.0.0/14149.64.0.1 to 149.67.255.254149.67.255.255262,142
82149.68.0.0/14149.68.0.1 to 149.71.255.254149.71.255.255262,142
83149.72.0.0/14149.72.0.1 to 149.75.255.254149.75.255.255262,142
84149.76.0.0/14149.76.0.1 to 149.79.255.254149.79.255.255262,142
85149.80.0.0/14149.80.0.1 to 149.83.255.254149.83.255.255262,142
86149.84.0.0/14149.84.0.1 to 149.87.255.254149.87.255.255262,142
87149.88.0.0/14149.88.0.1 to 149.91.255.254149.91.255.255262,142
88149.92.0.0/14149.92.0.1 to 149.95.255.254149.95.255.255262,142
89149.96.0.0/14149.96.0.1 to 149.99.255.254149.99.255.255262,142
90149.100.0.0/14149.100.0.1 to 149.103.255.254149.103.255.255262,142
91149.104.0.0/14149.104.0.1 to 149.107.255.254149.107.255.255262,142
92149.108.0.0/14149.108.0.1 to 149.111.255.254149.111.255.255262,142
93149.112.0.0/14149.112.0.1 to 149.115.255.254149.115.255.255262,142
94149.116.0.0/14149.116.0.1 to 149.119.255.254149.119.255.255262,142
95149.120.0.0/14149.120.0.1 to 149.123.255.254149.123.255.255262,142
96149.124.0.0/14149.124.0.1 to 149.127.255.254149.127.255.255262,142
97149.128.0.0/14149.128.0.1 to 149.131.255.254149.131.255.255262,142
98149.132.0.0/14149.132.0.1 to 149.135.255.254149.135.255.255262,142
99149.136.0.0/14149.136.0.1 to 149.139.255.254149.139.255.255262,142
100149.140.0.0/14149.140.0.1 to 149.143.255.254149.143.255.255262,142
101149.144.0.0/14149.144.0.1 to 149.147.255.254149.147.255.255262,142
102149.148.0.0/14149.148.0.1 to 149.151.255.254149.151.255.255262,142
103149.152.0.0/14149.152.0.1 to 149.155.255.254149.155.255.255262,142
104149.156.0.0/14149.156.0.1 to 149.159.255.254149.159.255.255262,142
105149.160.0.0/14149.160.0.1 to 149.163.255.254149.163.255.255262,142
106149.164.0.0/14149.164.0.1 to 149.167.255.254149.167.255.255262,142
107149.168.0.0/14149.168.0.1 to 149.171.255.254149.171.255.255262,142
108149.172.0.0/14149.172.0.1 to 149.175.255.254149.175.255.255262,142
109149.176.0.0/14149.176.0.1 to 149.179.255.254149.179.255.255262,142
110149.180.0.0/14149.180.0.1 to 149.183.255.254149.183.255.255262,142
111149.184.0.0/14149.184.0.1 to 149.187.255.254149.187.255.255262,142
112149.188.0.0/14149.188.0.1 to 149.191.255.254149.191.255.255262,142
113149.192.0.0/14149.192.0.1 to 149.195.255.254149.195.255.255262,142
114149.196.0.0/14149.196.0.1 to 149.199.255.254149.199.255.255262,142
115149.200.0.0/14149.200.0.1 to 149.203.255.254149.203.255.255262,142
116149.204.0.0/14149.204.0.1 to 149.207.255.254149.207.255.255262,142
117149.208.0.0/14149.208.0.1 to 149.211.255.254149.211.255.255262,142
118149.212.0.0/14149.212.0.1 to 149.215.255.254149.215.255.255262,142
119149.216.0.0/14149.216.0.1 to 149.219.255.254149.219.255.255262,142
120149.220.0.0/14149.220.0.1 to 149.223.255.254149.223.255.255262,142
121149.224.0.0/14149.224.0.1 to 149.227.255.254149.227.255.255262,142
122149.228.0.0/14149.228.0.1 to 149.231.255.254149.231.255.255262,142
123149.232.0.0/14149.232.0.1 to 149.235.255.254149.235.255.255262,142
124149.236.0.0/14149.236.0.1 to 149.239.255.254149.239.255.255262,142
125149.240.0.0/14149.240.0.1 to 149.243.255.254149.243.255.255262,142
126149.244.0.0/14149.244.0.1 to 149.247.255.254149.247.255.255262,142
127149.248.0.0/14149.248.0.1 to 149.251.255.254149.251.255.255262,142
128149.252.0.0/14149.252.0.1 to 149.255.255.254149.255.255.255262,142

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.