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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.

Network241.83.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
241.83.0.0
Broadcast address
241.83.127.255
First usable
241.83.0.1
Last usable
241.83.127.254
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
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F1530000 · Integer 4048748544 to 4048781311
Reverse DNS zones
0.83.241.in-addr.arpa
1.83.241.in-addr.arpa
2.83.241.in-addr.arpa
3.83.241.in-addr.arpa
4.83.241.in-addr.arpa
5.83.241.in-addr.arpa
6.83.241.in-addr.arpa
7.83.241.in-addr.arpa
8.83.241.in-addr.arpa
9.83.241.in-addr.arpa
10.83.241.in-addr.arpa
11.83.241.in-addr.arpa
12.83.241.in-addr.arpa
13.83.241.in-addr.arpa
14.83.241.in-addr.arpa
15.83.241.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
Address11110001.01010011.00000000.00000000241.83.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network11110001.01010011.00000000.00000000241.83.0.0
Broadcast11110001.01010011.01111111.11111111241.83.127.255
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)

241.83.0.0/17 makes 128 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1241.83.0.0/24241.83.0.1 to 241.83.0.254241.83.0.255254
2241.83.1.0/24241.83.1.1 to 241.83.1.254241.83.1.255254
3241.83.2.0/24241.83.2.1 to 241.83.2.254241.83.2.255254
4241.83.3.0/24241.83.3.1 to 241.83.3.254241.83.3.255254
5241.83.4.0/24241.83.4.1 to 241.83.4.254241.83.4.255254
6241.83.5.0/24241.83.5.1 to 241.83.5.254241.83.5.255254
7241.83.6.0/24241.83.6.1 to 241.83.6.254241.83.6.255254
8241.83.7.0/24241.83.7.1 to 241.83.7.254241.83.7.255254
9241.83.8.0/24241.83.8.1 to 241.83.8.254241.83.8.255254
10241.83.9.0/24241.83.9.1 to 241.83.9.254241.83.9.255254
11241.83.10.0/24241.83.10.1 to 241.83.10.254241.83.10.255254
12241.83.11.0/24241.83.11.1 to 241.83.11.254241.83.11.255254
13241.83.12.0/24241.83.12.1 to 241.83.12.254241.83.12.255254
14241.83.13.0/24241.83.13.1 to 241.83.13.254241.83.13.255254
15241.83.14.0/24241.83.14.1 to 241.83.14.254241.83.14.255254
16241.83.15.0/24241.83.15.1 to 241.83.15.254241.83.15.255254
17241.83.16.0/24241.83.16.1 to 241.83.16.254241.83.16.255254
18241.83.17.0/24241.83.17.1 to 241.83.17.254241.83.17.255254
19241.83.18.0/24241.83.18.1 to 241.83.18.254241.83.18.255254
20241.83.19.0/24241.83.19.1 to 241.83.19.254241.83.19.255254
21241.83.20.0/24241.83.20.1 to 241.83.20.254241.83.20.255254
22241.83.21.0/24241.83.21.1 to 241.83.21.254241.83.21.255254
23241.83.22.0/24241.83.22.1 to 241.83.22.254241.83.22.255254
24241.83.23.0/24241.83.23.1 to 241.83.23.254241.83.23.255254
25241.83.24.0/24241.83.24.1 to 241.83.24.254241.83.24.255254
26241.83.25.0/24241.83.25.1 to 241.83.25.254241.83.25.255254
27241.83.26.0/24241.83.26.1 to 241.83.26.254241.83.26.255254
28241.83.27.0/24241.83.27.1 to 241.83.27.254241.83.27.255254
29241.83.28.0/24241.83.28.1 to 241.83.28.254241.83.28.255254
30241.83.29.0/24241.83.29.1 to 241.83.29.254241.83.29.255254
31241.83.30.0/24241.83.30.1 to 241.83.30.254241.83.30.255254
32241.83.31.0/24241.83.31.1 to 241.83.31.254241.83.31.255254
33241.83.32.0/24241.83.32.1 to 241.83.32.254241.83.32.255254
34241.83.33.0/24241.83.33.1 to 241.83.33.254241.83.33.255254
35241.83.34.0/24241.83.34.1 to 241.83.34.254241.83.34.255254
36241.83.35.0/24241.83.35.1 to 241.83.35.254241.83.35.255254
37241.83.36.0/24241.83.36.1 to 241.83.36.254241.83.36.255254
38241.83.37.0/24241.83.37.1 to 241.83.37.254241.83.37.255254
39241.83.38.0/24241.83.38.1 to 241.83.38.254241.83.38.255254
40241.83.39.0/24241.83.39.1 to 241.83.39.254241.83.39.255254
41241.83.40.0/24241.83.40.1 to 241.83.40.254241.83.40.255254
42241.83.41.0/24241.83.41.1 to 241.83.41.254241.83.41.255254
43241.83.42.0/24241.83.42.1 to 241.83.42.254241.83.42.255254
44241.83.43.0/24241.83.43.1 to 241.83.43.254241.83.43.255254
45241.83.44.0/24241.83.44.1 to 241.83.44.254241.83.44.255254
46241.83.45.0/24241.83.45.1 to 241.83.45.254241.83.45.255254
47241.83.46.0/24241.83.46.1 to 241.83.46.254241.83.46.255254
48241.83.47.0/24241.83.47.1 to 241.83.47.254241.83.47.255254
49241.83.48.0/24241.83.48.1 to 241.83.48.254241.83.48.255254
50241.83.49.0/24241.83.49.1 to 241.83.49.254241.83.49.255254
51241.83.50.0/24241.83.50.1 to 241.83.50.254241.83.50.255254
52241.83.51.0/24241.83.51.1 to 241.83.51.254241.83.51.255254
53241.83.52.0/24241.83.52.1 to 241.83.52.254241.83.52.255254
54241.83.53.0/24241.83.53.1 to 241.83.53.254241.83.53.255254
55241.83.54.0/24241.83.54.1 to 241.83.54.254241.83.54.255254
56241.83.55.0/24241.83.55.1 to 241.83.55.254241.83.55.255254
57241.83.56.0/24241.83.56.1 to 241.83.56.254241.83.56.255254
58241.83.57.0/24241.83.57.1 to 241.83.57.254241.83.57.255254
59241.83.58.0/24241.83.58.1 to 241.83.58.254241.83.58.255254
60241.83.59.0/24241.83.59.1 to 241.83.59.254241.83.59.255254
61241.83.60.0/24241.83.60.1 to 241.83.60.254241.83.60.255254
62241.83.61.0/24241.83.61.1 to 241.83.61.254241.83.61.255254
63241.83.62.0/24241.83.62.1 to 241.83.62.254241.83.62.255254
64241.83.63.0/24241.83.63.1 to 241.83.63.254241.83.63.255254
65241.83.64.0/24241.83.64.1 to 241.83.64.254241.83.64.255254
66241.83.65.0/24241.83.65.1 to 241.83.65.254241.83.65.255254
67241.83.66.0/24241.83.66.1 to 241.83.66.254241.83.66.255254
68241.83.67.0/24241.83.67.1 to 241.83.67.254241.83.67.255254
69241.83.68.0/24241.83.68.1 to 241.83.68.254241.83.68.255254
70241.83.69.0/24241.83.69.1 to 241.83.69.254241.83.69.255254
71241.83.70.0/24241.83.70.1 to 241.83.70.254241.83.70.255254
72241.83.71.0/24241.83.71.1 to 241.83.71.254241.83.71.255254
73241.83.72.0/24241.83.72.1 to 241.83.72.254241.83.72.255254
74241.83.73.0/24241.83.73.1 to 241.83.73.254241.83.73.255254
75241.83.74.0/24241.83.74.1 to 241.83.74.254241.83.74.255254
76241.83.75.0/24241.83.75.1 to 241.83.75.254241.83.75.255254
77241.83.76.0/24241.83.76.1 to 241.83.76.254241.83.76.255254
78241.83.77.0/24241.83.77.1 to 241.83.77.254241.83.77.255254
79241.83.78.0/24241.83.78.1 to 241.83.78.254241.83.78.255254
80241.83.79.0/24241.83.79.1 to 241.83.79.254241.83.79.255254
81241.83.80.0/24241.83.80.1 to 241.83.80.254241.83.80.255254
82241.83.81.0/24241.83.81.1 to 241.83.81.254241.83.81.255254
83241.83.82.0/24241.83.82.1 to 241.83.82.254241.83.82.255254
84241.83.83.0/24241.83.83.1 to 241.83.83.254241.83.83.255254
85241.83.84.0/24241.83.84.1 to 241.83.84.254241.83.84.255254
86241.83.85.0/24241.83.85.1 to 241.83.85.254241.83.85.255254
87241.83.86.0/24241.83.86.1 to 241.83.86.254241.83.86.255254
88241.83.87.0/24241.83.87.1 to 241.83.87.254241.83.87.255254
89241.83.88.0/24241.83.88.1 to 241.83.88.254241.83.88.255254
90241.83.89.0/24241.83.89.1 to 241.83.89.254241.83.89.255254
91241.83.90.0/24241.83.90.1 to 241.83.90.254241.83.90.255254
92241.83.91.0/24241.83.91.1 to 241.83.91.254241.83.91.255254
93241.83.92.0/24241.83.92.1 to 241.83.92.254241.83.92.255254
94241.83.93.0/24241.83.93.1 to 241.83.93.254241.83.93.255254
95241.83.94.0/24241.83.94.1 to 241.83.94.254241.83.94.255254
96241.83.95.0/24241.83.95.1 to 241.83.95.254241.83.95.255254
97241.83.96.0/24241.83.96.1 to 241.83.96.254241.83.96.255254
98241.83.97.0/24241.83.97.1 to 241.83.97.254241.83.97.255254
99241.83.98.0/24241.83.98.1 to 241.83.98.254241.83.98.255254
100241.83.99.0/24241.83.99.1 to 241.83.99.254241.83.99.255254
101241.83.100.0/24241.83.100.1 to 241.83.100.254241.83.100.255254
102241.83.101.0/24241.83.101.1 to 241.83.101.254241.83.101.255254
103241.83.102.0/24241.83.102.1 to 241.83.102.254241.83.102.255254
104241.83.103.0/24241.83.103.1 to 241.83.103.254241.83.103.255254
105241.83.104.0/24241.83.104.1 to 241.83.104.254241.83.104.255254
106241.83.105.0/24241.83.105.1 to 241.83.105.254241.83.105.255254
107241.83.106.0/24241.83.106.1 to 241.83.106.254241.83.106.255254
108241.83.107.0/24241.83.107.1 to 241.83.107.254241.83.107.255254
109241.83.108.0/24241.83.108.1 to 241.83.108.254241.83.108.255254
110241.83.109.0/24241.83.109.1 to 241.83.109.254241.83.109.255254
111241.83.110.0/24241.83.110.1 to 241.83.110.254241.83.110.255254
112241.83.111.0/24241.83.111.1 to 241.83.111.254241.83.111.255254
113241.83.112.0/24241.83.112.1 to 241.83.112.254241.83.112.255254
114241.83.113.0/24241.83.113.1 to 241.83.113.254241.83.113.255254
115241.83.114.0/24241.83.114.1 to 241.83.114.254241.83.114.255254
116241.83.115.0/24241.83.115.1 to 241.83.115.254241.83.115.255254
117241.83.116.0/24241.83.116.1 to 241.83.116.254241.83.116.255254
118241.83.117.0/24241.83.117.1 to 241.83.117.254241.83.117.255254
119241.83.118.0/24241.83.118.1 to 241.83.118.254241.83.118.255254
120241.83.119.0/24241.83.119.1 to 241.83.119.254241.83.119.255254
121241.83.120.0/24241.83.120.1 to 241.83.120.254241.83.120.255254
122241.83.121.0/24241.83.121.1 to 241.83.121.254241.83.121.255254
123241.83.122.0/24241.83.122.1 to 241.83.122.254241.83.122.255254
124241.83.123.0/24241.83.123.1 to 241.83.123.254241.83.123.255254
125241.83.124.0/24241.83.124.1 to 241.83.124.254241.83.124.255254
126241.83.125.0/24241.83.125.1 to 241.83.125.254241.83.125.255254
127241.83.126.0/24241.83.126.1 to 241.83.126.254241.83.126.255254
128241.83.127.0/24241.83.127.1 to 241.83.127.254241.83.127.255254

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.