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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.

Network233.41.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
233.41.0.0
Broadcast address
233.41.127.255
First usable
233.41.0.1
Last usable
233.41.127.254
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
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex E9290000 · Integer 3911778304 to 3911811071
Reverse DNS zones
0.41.233.in-addr.arpa
1.41.233.in-addr.arpa
2.41.233.in-addr.arpa
3.41.233.in-addr.arpa
4.41.233.in-addr.arpa
5.41.233.in-addr.arpa
6.41.233.in-addr.arpa
7.41.233.in-addr.arpa
8.41.233.in-addr.arpa
9.41.233.in-addr.arpa
10.41.233.in-addr.arpa
11.41.233.in-addr.arpa
12.41.233.in-addr.arpa
13.41.233.in-addr.arpa
14.41.233.in-addr.arpa
15.41.233.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
Address11101001.00101001.00000000.00000000233.41.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network11101001.00101001.00000000.00000000233.41.0.0
Broadcast11101001.00101001.01111111.11111111233.41.127.255
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)

233.41.0.0/17 makes 128 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1233.41.0.0/24233.41.0.1 to 233.41.0.254233.41.0.255254
2233.41.1.0/24233.41.1.1 to 233.41.1.254233.41.1.255254
3233.41.2.0/24233.41.2.1 to 233.41.2.254233.41.2.255254
4233.41.3.0/24233.41.3.1 to 233.41.3.254233.41.3.255254
5233.41.4.0/24233.41.4.1 to 233.41.4.254233.41.4.255254
6233.41.5.0/24233.41.5.1 to 233.41.5.254233.41.5.255254
7233.41.6.0/24233.41.6.1 to 233.41.6.254233.41.6.255254
8233.41.7.0/24233.41.7.1 to 233.41.7.254233.41.7.255254
9233.41.8.0/24233.41.8.1 to 233.41.8.254233.41.8.255254
10233.41.9.0/24233.41.9.1 to 233.41.9.254233.41.9.255254
11233.41.10.0/24233.41.10.1 to 233.41.10.254233.41.10.255254
12233.41.11.0/24233.41.11.1 to 233.41.11.254233.41.11.255254
13233.41.12.0/24233.41.12.1 to 233.41.12.254233.41.12.255254
14233.41.13.0/24233.41.13.1 to 233.41.13.254233.41.13.255254
15233.41.14.0/24233.41.14.1 to 233.41.14.254233.41.14.255254
16233.41.15.0/24233.41.15.1 to 233.41.15.254233.41.15.255254
17233.41.16.0/24233.41.16.1 to 233.41.16.254233.41.16.255254
18233.41.17.0/24233.41.17.1 to 233.41.17.254233.41.17.255254
19233.41.18.0/24233.41.18.1 to 233.41.18.254233.41.18.255254
20233.41.19.0/24233.41.19.1 to 233.41.19.254233.41.19.255254
21233.41.20.0/24233.41.20.1 to 233.41.20.254233.41.20.255254
22233.41.21.0/24233.41.21.1 to 233.41.21.254233.41.21.255254
23233.41.22.0/24233.41.22.1 to 233.41.22.254233.41.22.255254
24233.41.23.0/24233.41.23.1 to 233.41.23.254233.41.23.255254
25233.41.24.0/24233.41.24.1 to 233.41.24.254233.41.24.255254
26233.41.25.0/24233.41.25.1 to 233.41.25.254233.41.25.255254
27233.41.26.0/24233.41.26.1 to 233.41.26.254233.41.26.255254
28233.41.27.0/24233.41.27.1 to 233.41.27.254233.41.27.255254
29233.41.28.0/24233.41.28.1 to 233.41.28.254233.41.28.255254
30233.41.29.0/24233.41.29.1 to 233.41.29.254233.41.29.255254
31233.41.30.0/24233.41.30.1 to 233.41.30.254233.41.30.255254
32233.41.31.0/24233.41.31.1 to 233.41.31.254233.41.31.255254
33233.41.32.0/24233.41.32.1 to 233.41.32.254233.41.32.255254
34233.41.33.0/24233.41.33.1 to 233.41.33.254233.41.33.255254
35233.41.34.0/24233.41.34.1 to 233.41.34.254233.41.34.255254
36233.41.35.0/24233.41.35.1 to 233.41.35.254233.41.35.255254
37233.41.36.0/24233.41.36.1 to 233.41.36.254233.41.36.255254
38233.41.37.0/24233.41.37.1 to 233.41.37.254233.41.37.255254
39233.41.38.0/24233.41.38.1 to 233.41.38.254233.41.38.255254
40233.41.39.0/24233.41.39.1 to 233.41.39.254233.41.39.255254
41233.41.40.0/24233.41.40.1 to 233.41.40.254233.41.40.255254
42233.41.41.0/24233.41.41.1 to 233.41.41.254233.41.41.255254
43233.41.42.0/24233.41.42.1 to 233.41.42.254233.41.42.255254
44233.41.43.0/24233.41.43.1 to 233.41.43.254233.41.43.255254
45233.41.44.0/24233.41.44.1 to 233.41.44.254233.41.44.255254
46233.41.45.0/24233.41.45.1 to 233.41.45.254233.41.45.255254
47233.41.46.0/24233.41.46.1 to 233.41.46.254233.41.46.255254
48233.41.47.0/24233.41.47.1 to 233.41.47.254233.41.47.255254
49233.41.48.0/24233.41.48.1 to 233.41.48.254233.41.48.255254
50233.41.49.0/24233.41.49.1 to 233.41.49.254233.41.49.255254
51233.41.50.0/24233.41.50.1 to 233.41.50.254233.41.50.255254
52233.41.51.0/24233.41.51.1 to 233.41.51.254233.41.51.255254
53233.41.52.0/24233.41.52.1 to 233.41.52.254233.41.52.255254
54233.41.53.0/24233.41.53.1 to 233.41.53.254233.41.53.255254
55233.41.54.0/24233.41.54.1 to 233.41.54.254233.41.54.255254
56233.41.55.0/24233.41.55.1 to 233.41.55.254233.41.55.255254
57233.41.56.0/24233.41.56.1 to 233.41.56.254233.41.56.255254
58233.41.57.0/24233.41.57.1 to 233.41.57.254233.41.57.255254
59233.41.58.0/24233.41.58.1 to 233.41.58.254233.41.58.255254
60233.41.59.0/24233.41.59.1 to 233.41.59.254233.41.59.255254
61233.41.60.0/24233.41.60.1 to 233.41.60.254233.41.60.255254
62233.41.61.0/24233.41.61.1 to 233.41.61.254233.41.61.255254
63233.41.62.0/24233.41.62.1 to 233.41.62.254233.41.62.255254
64233.41.63.0/24233.41.63.1 to 233.41.63.254233.41.63.255254
65233.41.64.0/24233.41.64.1 to 233.41.64.254233.41.64.255254
66233.41.65.0/24233.41.65.1 to 233.41.65.254233.41.65.255254
67233.41.66.0/24233.41.66.1 to 233.41.66.254233.41.66.255254
68233.41.67.0/24233.41.67.1 to 233.41.67.254233.41.67.255254
69233.41.68.0/24233.41.68.1 to 233.41.68.254233.41.68.255254
70233.41.69.0/24233.41.69.1 to 233.41.69.254233.41.69.255254
71233.41.70.0/24233.41.70.1 to 233.41.70.254233.41.70.255254
72233.41.71.0/24233.41.71.1 to 233.41.71.254233.41.71.255254
73233.41.72.0/24233.41.72.1 to 233.41.72.254233.41.72.255254
74233.41.73.0/24233.41.73.1 to 233.41.73.254233.41.73.255254
75233.41.74.0/24233.41.74.1 to 233.41.74.254233.41.74.255254
76233.41.75.0/24233.41.75.1 to 233.41.75.254233.41.75.255254
77233.41.76.0/24233.41.76.1 to 233.41.76.254233.41.76.255254
78233.41.77.0/24233.41.77.1 to 233.41.77.254233.41.77.255254
79233.41.78.0/24233.41.78.1 to 233.41.78.254233.41.78.255254
80233.41.79.0/24233.41.79.1 to 233.41.79.254233.41.79.255254
81233.41.80.0/24233.41.80.1 to 233.41.80.254233.41.80.255254
82233.41.81.0/24233.41.81.1 to 233.41.81.254233.41.81.255254
83233.41.82.0/24233.41.82.1 to 233.41.82.254233.41.82.255254
84233.41.83.0/24233.41.83.1 to 233.41.83.254233.41.83.255254
85233.41.84.0/24233.41.84.1 to 233.41.84.254233.41.84.255254
86233.41.85.0/24233.41.85.1 to 233.41.85.254233.41.85.255254
87233.41.86.0/24233.41.86.1 to 233.41.86.254233.41.86.255254
88233.41.87.0/24233.41.87.1 to 233.41.87.254233.41.87.255254
89233.41.88.0/24233.41.88.1 to 233.41.88.254233.41.88.255254
90233.41.89.0/24233.41.89.1 to 233.41.89.254233.41.89.255254
91233.41.90.0/24233.41.90.1 to 233.41.90.254233.41.90.255254
92233.41.91.0/24233.41.91.1 to 233.41.91.254233.41.91.255254
93233.41.92.0/24233.41.92.1 to 233.41.92.254233.41.92.255254
94233.41.93.0/24233.41.93.1 to 233.41.93.254233.41.93.255254
95233.41.94.0/24233.41.94.1 to 233.41.94.254233.41.94.255254
96233.41.95.0/24233.41.95.1 to 233.41.95.254233.41.95.255254
97233.41.96.0/24233.41.96.1 to 233.41.96.254233.41.96.255254
98233.41.97.0/24233.41.97.1 to 233.41.97.254233.41.97.255254
99233.41.98.0/24233.41.98.1 to 233.41.98.254233.41.98.255254
100233.41.99.0/24233.41.99.1 to 233.41.99.254233.41.99.255254
101233.41.100.0/24233.41.100.1 to 233.41.100.254233.41.100.255254
102233.41.101.0/24233.41.101.1 to 233.41.101.254233.41.101.255254
103233.41.102.0/24233.41.102.1 to 233.41.102.254233.41.102.255254
104233.41.103.0/24233.41.103.1 to 233.41.103.254233.41.103.255254
105233.41.104.0/24233.41.104.1 to 233.41.104.254233.41.104.255254
106233.41.105.0/24233.41.105.1 to 233.41.105.254233.41.105.255254
107233.41.106.0/24233.41.106.1 to 233.41.106.254233.41.106.255254
108233.41.107.0/24233.41.107.1 to 233.41.107.254233.41.107.255254
109233.41.108.0/24233.41.108.1 to 233.41.108.254233.41.108.255254
110233.41.109.0/24233.41.109.1 to 233.41.109.254233.41.109.255254
111233.41.110.0/24233.41.110.1 to 233.41.110.254233.41.110.255254
112233.41.111.0/24233.41.111.1 to 233.41.111.254233.41.111.255254
113233.41.112.0/24233.41.112.1 to 233.41.112.254233.41.112.255254
114233.41.113.0/24233.41.113.1 to 233.41.113.254233.41.113.255254
115233.41.114.0/24233.41.114.1 to 233.41.114.254233.41.114.255254
116233.41.115.0/24233.41.115.1 to 233.41.115.254233.41.115.255254
117233.41.116.0/24233.41.116.1 to 233.41.116.254233.41.116.255254
118233.41.117.0/24233.41.117.1 to 233.41.117.254233.41.117.255254
119233.41.118.0/24233.41.118.1 to 233.41.118.254233.41.118.255254
120233.41.119.0/24233.41.119.1 to 233.41.119.254233.41.119.255254
121233.41.120.0/24233.41.120.1 to 233.41.120.254233.41.120.255254
122233.41.121.0/24233.41.121.1 to 233.41.121.254233.41.121.255254
123233.41.122.0/24233.41.122.1 to 233.41.122.254233.41.122.255254
124233.41.123.0/24233.41.123.1 to 233.41.123.254233.41.123.255254
125233.41.124.0/24233.41.124.1 to 233.41.124.254233.41.124.255254
126233.41.125.0/24233.41.125.1 to 233.41.125.254233.41.125.255254
127233.41.126.0/24233.41.126.1 to 233.41.126.254233.41.126.255254
128233.41.127.0/24233.41.127.1 to 233.41.127.254233.41.127.255254

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.