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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.

Network202.44.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
202.44.0.0
Broadcast address
202.44.127.255
First usable
202.44.0.1
Last usable
202.44.127.254
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
C (default /24)
As numbers
Hex CA2C0000 · Integer 3391881216 to 3391913983
Reverse DNS zones
0.44.202.in-addr.arpa
1.44.202.in-addr.arpa
2.44.202.in-addr.arpa
3.44.202.in-addr.arpa
4.44.202.in-addr.arpa
5.44.202.in-addr.arpa
6.44.202.in-addr.arpa
7.44.202.in-addr.arpa
8.44.202.in-addr.arpa
9.44.202.in-addr.arpa
10.44.202.in-addr.arpa
11.44.202.in-addr.arpa
12.44.202.in-addr.arpa
13.44.202.in-addr.arpa
14.44.202.in-addr.arpa
15.44.202.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
Address11001010.00101100.00000000.00000000202.44.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network11001010.00101100.00000000.00000000202.44.0.0
Broadcast11001010.00101100.01111111.11111111202.44.127.255
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)

202.44.0.0/17 makes 128 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1202.44.0.0/24202.44.0.1 to 202.44.0.254202.44.0.255254
2202.44.1.0/24202.44.1.1 to 202.44.1.254202.44.1.255254
3202.44.2.0/24202.44.2.1 to 202.44.2.254202.44.2.255254
4202.44.3.0/24202.44.3.1 to 202.44.3.254202.44.3.255254
5202.44.4.0/24202.44.4.1 to 202.44.4.254202.44.4.255254
6202.44.5.0/24202.44.5.1 to 202.44.5.254202.44.5.255254
7202.44.6.0/24202.44.6.1 to 202.44.6.254202.44.6.255254
8202.44.7.0/24202.44.7.1 to 202.44.7.254202.44.7.255254
9202.44.8.0/24202.44.8.1 to 202.44.8.254202.44.8.255254
10202.44.9.0/24202.44.9.1 to 202.44.9.254202.44.9.255254
11202.44.10.0/24202.44.10.1 to 202.44.10.254202.44.10.255254
12202.44.11.0/24202.44.11.1 to 202.44.11.254202.44.11.255254
13202.44.12.0/24202.44.12.1 to 202.44.12.254202.44.12.255254
14202.44.13.0/24202.44.13.1 to 202.44.13.254202.44.13.255254
15202.44.14.0/24202.44.14.1 to 202.44.14.254202.44.14.255254
16202.44.15.0/24202.44.15.1 to 202.44.15.254202.44.15.255254
17202.44.16.0/24202.44.16.1 to 202.44.16.254202.44.16.255254
18202.44.17.0/24202.44.17.1 to 202.44.17.254202.44.17.255254
19202.44.18.0/24202.44.18.1 to 202.44.18.254202.44.18.255254
20202.44.19.0/24202.44.19.1 to 202.44.19.254202.44.19.255254
21202.44.20.0/24202.44.20.1 to 202.44.20.254202.44.20.255254
22202.44.21.0/24202.44.21.1 to 202.44.21.254202.44.21.255254
23202.44.22.0/24202.44.22.1 to 202.44.22.254202.44.22.255254
24202.44.23.0/24202.44.23.1 to 202.44.23.254202.44.23.255254
25202.44.24.0/24202.44.24.1 to 202.44.24.254202.44.24.255254
26202.44.25.0/24202.44.25.1 to 202.44.25.254202.44.25.255254
27202.44.26.0/24202.44.26.1 to 202.44.26.254202.44.26.255254
28202.44.27.0/24202.44.27.1 to 202.44.27.254202.44.27.255254
29202.44.28.0/24202.44.28.1 to 202.44.28.254202.44.28.255254
30202.44.29.0/24202.44.29.1 to 202.44.29.254202.44.29.255254
31202.44.30.0/24202.44.30.1 to 202.44.30.254202.44.30.255254
32202.44.31.0/24202.44.31.1 to 202.44.31.254202.44.31.255254
33202.44.32.0/24202.44.32.1 to 202.44.32.254202.44.32.255254
34202.44.33.0/24202.44.33.1 to 202.44.33.254202.44.33.255254
35202.44.34.0/24202.44.34.1 to 202.44.34.254202.44.34.255254
36202.44.35.0/24202.44.35.1 to 202.44.35.254202.44.35.255254
37202.44.36.0/24202.44.36.1 to 202.44.36.254202.44.36.255254
38202.44.37.0/24202.44.37.1 to 202.44.37.254202.44.37.255254
39202.44.38.0/24202.44.38.1 to 202.44.38.254202.44.38.255254
40202.44.39.0/24202.44.39.1 to 202.44.39.254202.44.39.255254
41202.44.40.0/24202.44.40.1 to 202.44.40.254202.44.40.255254
42202.44.41.0/24202.44.41.1 to 202.44.41.254202.44.41.255254
43202.44.42.0/24202.44.42.1 to 202.44.42.254202.44.42.255254
44202.44.43.0/24202.44.43.1 to 202.44.43.254202.44.43.255254
45202.44.44.0/24202.44.44.1 to 202.44.44.254202.44.44.255254
46202.44.45.0/24202.44.45.1 to 202.44.45.254202.44.45.255254
47202.44.46.0/24202.44.46.1 to 202.44.46.254202.44.46.255254
48202.44.47.0/24202.44.47.1 to 202.44.47.254202.44.47.255254
49202.44.48.0/24202.44.48.1 to 202.44.48.254202.44.48.255254
50202.44.49.0/24202.44.49.1 to 202.44.49.254202.44.49.255254
51202.44.50.0/24202.44.50.1 to 202.44.50.254202.44.50.255254
52202.44.51.0/24202.44.51.1 to 202.44.51.254202.44.51.255254
53202.44.52.0/24202.44.52.1 to 202.44.52.254202.44.52.255254
54202.44.53.0/24202.44.53.1 to 202.44.53.254202.44.53.255254
55202.44.54.0/24202.44.54.1 to 202.44.54.254202.44.54.255254
56202.44.55.0/24202.44.55.1 to 202.44.55.254202.44.55.255254
57202.44.56.0/24202.44.56.1 to 202.44.56.254202.44.56.255254
58202.44.57.0/24202.44.57.1 to 202.44.57.254202.44.57.255254
59202.44.58.0/24202.44.58.1 to 202.44.58.254202.44.58.255254
60202.44.59.0/24202.44.59.1 to 202.44.59.254202.44.59.255254
61202.44.60.0/24202.44.60.1 to 202.44.60.254202.44.60.255254
62202.44.61.0/24202.44.61.1 to 202.44.61.254202.44.61.255254
63202.44.62.0/24202.44.62.1 to 202.44.62.254202.44.62.255254
64202.44.63.0/24202.44.63.1 to 202.44.63.254202.44.63.255254
65202.44.64.0/24202.44.64.1 to 202.44.64.254202.44.64.255254
66202.44.65.0/24202.44.65.1 to 202.44.65.254202.44.65.255254
67202.44.66.0/24202.44.66.1 to 202.44.66.254202.44.66.255254
68202.44.67.0/24202.44.67.1 to 202.44.67.254202.44.67.255254
69202.44.68.0/24202.44.68.1 to 202.44.68.254202.44.68.255254
70202.44.69.0/24202.44.69.1 to 202.44.69.254202.44.69.255254
71202.44.70.0/24202.44.70.1 to 202.44.70.254202.44.70.255254
72202.44.71.0/24202.44.71.1 to 202.44.71.254202.44.71.255254
73202.44.72.0/24202.44.72.1 to 202.44.72.254202.44.72.255254
74202.44.73.0/24202.44.73.1 to 202.44.73.254202.44.73.255254
75202.44.74.0/24202.44.74.1 to 202.44.74.254202.44.74.255254
76202.44.75.0/24202.44.75.1 to 202.44.75.254202.44.75.255254
77202.44.76.0/24202.44.76.1 to 202.44.76.254202.44.76.255254
78202.44.77.0/24202.44.77.1 to 202.44.77.254202.44.77.255254
79202.44.78.0/24202.44.78.1 to 202.44.78.254202.44.78.255254
80202.44.79.0/24202.44.79.1 to 202.44.79.254202.44.79.255254
81202.44.80.0/24202.44.80.1 to 202.44.80.254202.44.80.255254
82202.44.81.0/24202.44.81.1 to 202.44.81.254202.44.81.255254
83202.44.82.0/24202.44.82.1 to 202.44.82.254202.44.82.255254
84202.44.83.0/24202.44.83.1 to 202.44.83.254202.44.83.255254
85202.44.84.0/24202.44.84.1 to 202.44.84.254202.44.84.255254
86202.44.85.0/24202.44.85.1 to 202.44.85.254202.44.85.255254
87202.44.86.0/24202.44.86.1 to 202.44.86.254202.44.86.255254
88202.44.87.0/24202.44.87.1 to 202.44.87.254202.44.87.255254
89202.44.88.0/24202.44.88.1 to 202.44.88.254202.44.88.255254
90202.44.89.0/24202.44.89.1 to 202.44.89.254202.44.89.255254
91202.44.90.0/24202.44.90.1 to 202.44.90.254202.44.90.255254
92202.44.91.0/24202.44.91.1 to 202.44.91.254202.44.91.255254
93202.44.92.0/24202.44.92.1 to 202.44.92.254202.44.92.255254
94202.44.93.0/24202.44.93.1 to 202.44.93.254202.44.93.255254
95202.44.94.0/24202.44.94.1 to 202.44.94.254202.44.94.255254
96202.44.95.0/24202.44.95.1 to 202.44.95.254202.44.95.255254
97202.44.96.0/24202.44.96.1 to 202.44.96.254202.44.96.255254
98202.44.97.0/24202.44.97.1 to 202.44.97.254202.44.97.255254
99202.44.98.0/24202.44.98.1 to 202.44.98.254202.44.98.255254
100202.44.99.0/24202.44.99.1 to 202.44.99.254202.44.99.255254
101202.44.100.0/24202.44.100.1 to 202.44.100.254202.44.100.255254
102202.44.101.0/24202.44.101.1 to 202.44.101.254202.44.101.255254
103202.44.102.0/24202.44.102.1 to 202.44.102.254202.44.102.255254
104202.44.103.0/24202.44.103.1 to 202.44.103.254202.44.103.255254
105202.44.104.0/24202.44.104.1 to 202.44.104.254202.44.104.255254
106202.44.105.0/24202.44.105.1 to 202.44.105.254202.44.105.255254
107202.44.106.0/24202.44.106.1 to 202.44.106.254202.44.106.255254
108202.44.107.0/24202.44.107.1 to 202.44.107.254202.44.107.255254
109202.44.108.0/24202.44.108.1 to 202.44.108.254202.44.108.255254
110202.44.109.0/24202.44.109.1 to 202.44.109.254202.44.109.255254
111202.44.110.0/24202.44.110.1 to 202.44.110.254202.44.110.255254
112202.44.111.0/24202.44.111.1 to 202.44.111.254202.44.111.255254
113202.44.112.0/24202.44.112.1 to 202.44.112.254202.44.112.255254
114202.44.113.0/24202.44.113.1 to 202.44.113.254202.44.113.255254
115202.44.114.0/24202.44.114.1 to 202.44.114.254202.44.114.255254
116202.44.115.0/24202.44.115.1 to 202.44.115.254202.44.115.255254
117202.44.116.0/24202.44.116.1 to 202.44.116.254202.44.116.255254
118202.44.117.0/24202.44.117.1 to 202.44.117.254202.44.117.255254
119202.44.118.0/24202.44.118.1 to 202.44.118.254202.44.118.255254
120202.44.119.0/24202.44.119.1 to 202.44.119.254202.44.119.255254
121202.44.120.0/24202.44.120.1 to 202.44.120.254202.44.120.255254
122202.44.121.0/24202.44.121.1 to 202.44.121.254202.44.121.255254
123202.44.122.0/24202.44.122.1 to 202.44.122.254202.44.122.255254
124202.44.123.0/24202.44.123.1 to 202.44.123.254202.44.123.255254
125202.44.124.0/24202.44.124.1 to 202.44.124.254202.44.124.255254
126202.44.125.0/24202.44.125.1 to 202.44.125.254202.44.125.255254
127202.44.126.0/24202.44.126.1 to 202.44.126.254202.44.126.255254
128202.44.127.0/24202.44.127.1 to 202.44.127.254202.44.127.255254

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.