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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.

Network141.63.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
141.63.0.0
Broadcast address
141.63.127.255
First usable
141.63.0.1
Last usable
141.63.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
B (default /16)
As numbers
Hex 8D3F0000 · Integer 2369716224 to 2369748991
Reverse DNS zones
0.63.141.in-addr.arpa
1.63.141.in-addr.arpa
2.63.141.in-addr.arpa
3.63.141.in-addr.arpa
4.63.141.in-addr.arpa
5.63.141.in-addr.arpa
6.63.141.in-addr.arpa
7.63.141.in-addr.arpa
8.63.141.in-addr.arpa
9.63.141.in-addr.arpa
10.63.141.in-addr.arpa
11.63.141.in-addr.arpa
12.63.141.in-addr.arpa
13.63.141.in-addr.arpa
14.63.141.in-addr.arpa
15.63.141.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10001101.00111111.00000000.00000000141.63.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network10001101.00111111.00000000.00000000141.63.0.0
Broadcast10001101.00111111.01111111.11111111141.63.127.255
Split into smaller subnets/24
/18 (2)/19 (4)/20 (8)/21 (16)/22 (32)/23 (64)/24 (128)/25 (256)/26 (512)/27 (1,024)/28 (2,048)/29 (4,096)

141.63.0.0/17 makes 128 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1141.63.0.0/24141.63.0.1 to 141.63.0.254141.63.0.255254
2141.63.1.0/24141.63.1.1 to 141.63.1.254141.63.1.255254
3141.63.2.0/24141.63.2.1 to 141.63.2.254141.63.2.255254
4141.63.3.0/24141.63.3.1 to 141.63.3.254141.63.3.255254
5141.63.4.0/24141.63.4.1 to 141.63.4.254141.63.4.255254
6141.63.5.0/24141.63.5.1 to 141.63.5.254141.63.5.255254
7141.63.6.0/24141.63.6.1 to 141.63.6.254141.63.6.255254
8141.63.7.0/24141.63.7.1 to 141.63.7.254141.63.7.255254
9141.63.8.0/24141.63.8.1 to 141.63.8.254141.63.8.255254
10141.63.9.0/24141.63.9.1 to 141.63.9.254141.63.9.255254
11141.63.10.0/24141.63.10.1 to 141.63.10.254141.63.10.255254
12141.63.11.0/24141.63.11.1 to 141.63.11.254141.63.11.255254
13141.63.12.0/24141.63.12.1 to 141.63.12.254141.63.12.255254
14141.63.13.0/24141.63.13.1 to 141.63.13.254141.63.13.255254
15141.63.14.0/24141.63.14.1 to 141.63.14.254141.63.14.255254
16141.63.15.0/24141.63.15.1 to 141.63.15.254141.63.15.255254
17141.63.16.0/24141.63.16.1 to 141.63.16.254141.63.16.255254
18141.63.17.0/24141.63.17.1 to 141.63.17.254141.63.17.255254
19141.63.18.0/24141.63.18.1 to 141.63.18.254141.63.18.255254
20141.63.19.0/24141.63.19.1 to 141.63.19.254141.63.19.255254
21141.63.20.0/24141.63.20.1 to 141.63.20.254141.63.20.255254
22141.63.21.0/24141.63.21.1 to 141.63.21.254141.63.21.255254
23141.63.22.0/24141.63.22.1 to 141.63.22.254141.63.22.255254
24141.63.23.0/24141.63.23.1 to 141.63.23.254141.63.23.255254
25141.63.24.0/24141.63.24.1 to 141.63.24.254141.63.24.255254
26141.63.25.0/24141.63.25.1 to 141.63.25.254141.63.25.255254
27141.63.26.0/24141.63.26.1 to 141.63.26.254141.63.26.255254
28141.63.27.0/24141.63.27.1 to 141.63.27.254141.63.27.255254
29141.63.28.0/24141.63.28.1 to 141.63.28.254141.63.28.255254
30141.63.29.0/24141.63.29.1 to 141.63.29.254141.63.29.255254
31141.63.30.0/24141.63.30.1 to 141.63.30.254141.63.30.255254
32141.63.31.0/24141.63.31.1 to 141.63.31.254141.63.31.255254
33141.63.32.0/24141.63.32.1 to 141.63.32.254141.63.32.255254
34141.63.33.0/24141.63.33.1 to 141.63.33.254141.63.33.255254
35141.63.34.0/24141.63.34.1 to 141.63.34.254141.63.34.255254
36141.63.35.0/24141.63.35.1 to 141.63.35.254141.63.35.255254
37141.63.36.0/24141.63.36.1 to 141.63.36.254141.63.36.255254
38141.63.37.0/24141.63.37.1 to 141.63.37.254141.63.37.255254
39141.63.38.0/24141.63.38.1 to 141.63.38.254141.63.38.255254
40141.63.39.0/24141.63.39.1 to 141.63.39.254141.63.39.255254
41141.63.40.0/24141.63.40.1 to 141.63.40.254141.63.40.255254
42141.63.41.0/24141.63.41.1 to 141.63.41.254141.63.41.255254
43141.63.42.0/24141.63.42.1 to 141.63.42.254141.63.42.255254
44141.63.43.0/24141.63.43.1 to 141.63.43.254141.63.43.255254
45141.63.44.0/24141.63.44.1 to 141.63.44.254141.63.44.255254
46141.63.45.0/24141.63.45.1 to 141.63.45.254141.63.45.255254
47141.63.46.0/24141.63.46.1 to 141.63.46.254141.63.46.255254
48141.63.47.0/24141.63.47.1 to 141.63.47.254141.63.47.255254
49141.63.48.0/24141.63.48.1 to 141.63.48.254141.63.48.255254
50141.63.49.0/24141.63.49.1 to 141.63.49.254141.63.49.255254
51141.63.50.0/24141.63.50.1 to 141.63.50.254141.63.50.255254
52141.63.51.0/24141.63.51.1 to 141.63.51.254141.63.51.255254
53141.63.52.0/24141.63.52.1 to 141.63.52.254141.63.52.255254
54141.63.53.0/24141.63.53.1 to 141.63.53.254141.63.53.255254
55141.63.54.0/24141.63.54.1 to 141.63.54.254141.63.54.255254
56141.63.55.0/24141.63.55.1 to 141.63.55.254141.63.55.255254
57141.63.56.0/24141.63.56.1 to 141.63.56.254141.63.56.255254
58141.63.57.0/24141.63.57.1 to 141.63.57.254141.63.57.255254
59141.63.58.0/24141.63.58.1 to 141.63.58.254141.63.58.255254
60141.63.59.0/24141.63.59.1 to 141.63.59.254141.63.59.255254
61141.63.60.0/24141.63.60.1 to 141.63.60.254141.63.60.255254
62141.63.61.0/24141.63.61.1 to 141.63.61.254141.63.61.255254
63141.63.62.0/24141.63.62.1 to 141.63.62.254141.63.62.255254
64141.63.63.0/24141.63.63.1 to 141.63.63.254141.63.63.255254
65141.63.64.0/24141.63.64.1 to 141.63.64.254141.63.64.255254
66141.63.65.0/24141.63.65.1 to 141.63.65.254141.63.65.255254
67141.63.66.0/24141.63.66.1 to 141.63.66.254141.63.66.255254
68141.63.67.0/24141.63.67.1 to 141.63.67.254141.63.67.255254
69141.63.68.0/24141.63.68.1 to 141.63.68.254141.63.68.255254
70141.63.69.0/24141.63.69.1 to 141.63.69.254141.63.69.255254
71141.63.70.0/24141.63.70.1 to 141.63.70.254141.63.70.255254
72141.63.71.0/24141.63.71.1 to 141.63.71.254141.63.71.255254
73141.63.72.0/24141.63.72.1 to 141.63.72.254141.63.72.255254
74141.63.73.0/24141.63.73.1 to 141.63.73.254141.63.73.255254
75141.63.74.0/24141.63.74.1 to 141.63.74.254141.63.74.255254
76141.63.75.0/24141.63.75.1 to 141.63.75.254141.63.75.255254
77141.63.76.0/24141.63.76.1 to 141.63.76.254141.63.76.255254
78141.63.77.0/24141.63.77.1 to 141.63.77.254141.63.77.255254
79141.63.78.0/24141.63.78.1 to 141.63.78.254141.63.78.255254
80141.63.79.0/24141.63.79.1 to 141.63.79.254141.63.79.255254
81141.63.80.0/24141.63.80.1 to 141.63.80.254141.63.80.255254
82141.63.81.0/24141.63.81.1 to 141.63.81.254141.63.81.255254
83141.63.82.0/24141.63.82.1 to 141.63.82.254141.63.82.255254
84141.63.83.0/24141.63.83.1 to 141.63.83.254141.63.83.255254
85141.63.84.0/24141.63.84.1 to 141.63.84.254141.63.84.255254
86141.63.85.0/24141.63.85.1 to 141.63.85.254141.63.85.255254
87141.63.86.0/24141.63.86.1 to 141.63.86.254141.63.86.255254
88141.63.87.0/24141.63.87.1 to 141.63.87.254141.63.87.255254
89141.63.88.0/24141.63.88.1 to 141.63.88.254141.63.88.255254
90141.63.89.0/24141.63.89.1 to 141.63.89.254141.63.89.255254
91141.63.90.0/24141.63.90.1 to 141.63.90.254141.63.90.255254
92141.63.91.0/24141.63.91.1 to 141.63.91.254141.63.91.255254
93141.63.92.0/24141.63.92.1 to 141.63.92.254141.63.92.255254
94141.63.93.0/24141.63.93.1 to 141.63.93.254141.63.93.255254
95141.63.94.0/24141.63.94.1 to 141.63.94.254141.63.94.255254
96141.63.95.0/24141.63.95.1 to 141.63.95.254141.63.95.255254
97141.63.96.0/24141.63.96.1 to 141.63.96.254141.63.96.255254
98141.63.97.0/24141.63.97.1 to 141.63.97.254141.63.97.255254
99141.63.98.0/24141.63.98.1 to 141.63.98.254141.63.98.255254
100141.63.99.0/24141.63.99.1 to 141.63.99.254141.63.99.255254
101141.63.100.0/24141.63.100.1 to 141.63.100.254141.63.100.255254
102141.63.101.0/24141.63.101.1 to 141.63.101.254141.63.101.255254
103141.63.102.0/24141.63.102.1 to 141.63.102.254141.63.102.255254
104141.63.103.0/24141.63.103.1 to 141.63.103.254141.63.103.255254
105141.63.104.0/24141.63.104.1 to 141.63.104.254141.63.104.255254
106141.63.105.0/24141.63.105.1 to 141.63.105.254141.63.105.255254
107141.63.106.0/24141.63.106.1 to 141.63.106.254141.63.106.255254
108141.63.107.0/24141.63.107.1 to 141.63.107.254141.63.107.255254
109141.63.108.0/24141.63.108.1 to 141.63.108.254141.63.108.255254
110141.63.109.0/24141.63.109.1 to 141.63.109.254141.63.109.255254
111141.63.110.0/24141.63.110.1 to 141.63.110.254141.63.110.255254
112141.63.111.0/24141.63.111.1 to 141.63.111.254141.63.111.255254
113141.63.112.0/24141.63.112.1 to 141.63.112.254141.63.112.255254
114141.63.113.0/24141.63.113.1 to 141.63.113.254141.63.113.255254
115141.63.114.0/24141.63.114.1 to 141.63.114.254141.63.114.255254
116141.63.115.0/24141.63.115.1 to 141.63.115.254141.63.115.255254
117141.63.116.0/24141.63.116.1 to 141.63.116.254141.63.116.255254
118141.63.117.0/24141.63.117.1 to 141.63.117.254141.63.117.255254
119141.63.118.0/24141.63.118.1 to 141.63.118.254141.63.118.255254
120141.63.119.0/24141.63.119.1 to 141.63.119.254141.63.119.255254
121141.63.120.0/24141.63.120.1 to 141.63.120.254141.63.120.255254
122141.63.121.0/24141.63.121.1 to 141.63.121.254141.63.121.255254
123141.63.122.0/24141.63.122.1 to 141.63.122.254141.63.122.255254
124141.63.123.0/24141.63.123.1 to 141.63.123.254141.63.123.255254
125141.63.124.0/24141.63.124.1 to 141.63.124.254141.63.124.255254
126141.63.125.0/24141.63.125.1 to 141.63.125.254141.63.125.255254
127141.63.126.0/24141.63.126.1 to 141.63.126.254141.63.126.255254
128141.63.127.0/24141.63.127.1 to 141.63.127.254141.63.127.255254

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.