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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.

Network241.0.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
241.0.0.0
Broadcast address
241.63.255.255
First usable
241.0.0.1
Last usable
241.63.255.254
Usable hosts
4,194,302 (4,194,304 less the network and broadcast addresses)
Subnet mask
255.192.0.0
Wildcard mask
0.63.255.255 (Cisco ACLs, OSPF)
Prefix length
/10
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F1000000 · Integer 4043309056 to 4047503359
Reverse DNS zones
0.241.in-addr.arpa
1.241.in-addr.arpa
2.241.in-addr.arpa
3.241.in-addr.arpa
4.241.in-addr.arpa
5.241.in-addr.arpa
6.241.in-addr.arpa
7.241.in-addr.arpa
8.241.in-addr.arpa
9.241.in-addr.arpa
10.241.in-addr.arpa
11.241.in-addr.arpa
12.241.in-addr.arpa
13.241.in-addr.arpa
14.241.in-addr.arpa
15.241.in-addr.arpa
and 48 more
/10 is not on a 8-bit boundary, so it takes 64 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110001.00000000.00000000.00000000241.0.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network11110001.00000000.00000000.00000000241.0.0.0
Broadcast11110001.00111111.11111111.11111111241.63.255.255
Split into smaller subnets/17
/11 (2)/12 (4)/13 (8)/14 (16)/15 (32)/16 (64)/17 (128)/18 (256)/19 (512)/20 (1,024)/21 (2,048)/22 (4,096)

241.0.0.0/10 makes 128 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1241.0.0.0/17241.0.0.1 to 241.0.127.254241.0.127.25532,766
2241.0.128.0/17241.0.128.1 to 241.0.255.254241.0.255.25532,766
3241.1.0.0/17241.1.0.1 to 241.1.127.254241.1.127.25532,766
4241.1.128.0/17241.1.128.1 to 241.1.255.254241.1.255.25532,766
5241.2.0.0/17241.2.0.1 to 241.2.127.254241.2.127.25532,766
6241.2.128.0/17241.2.128.1 to 241.2.255.254241.2.255.25532,766
7241.3.0.0/17241.3.0.1 to 241.3.127.254241.3.127.25532,766
8241.3.128.0/17241.3.128.1 to 241.3.255.254241.3.255.25532,766
9241.4.0.0/17241.4.0.1 to 241.4.127.254241.4.127.25532,766
10241.4.128.0/17241.4.128.1 to 241.4.255.254241.4.255.25532,766
11241.5.0.0/17241.5.0.1 to 241.5.127.254241.5.127.25532,766
12241.5.128.0/17241.5.128.1 to 241.5.255.254241.5.255.25532,766
13241.6.0.0/17241.6.0.1 to 241.6.127.254241.6.127.25532,766
14241.6.128.0/17241.6.128.1 to 241.6.255.254241.6.255.25532,766
15241.7.0.0/17241.7.0.1 to 241.7.127.254241.7.127.25532,766
16241.7.128.0/17241.7.128.1 to 241.7.255.254241.7.255.25532,766
17241.8.0.0/17241.8.0.1 to 241.8.127.254241.8.127.25532,766
18241.8.128.0/17241.8.128.1 to 241.8.255.254241.8.255.25532,766
19241.9.0.0/17241.9.0.1 to 241.9.127.254241.9.127.25532,766
20241.9.128.0/17241.9.128.1 to 241.9.255.254241.9.255.25532,766
21241.10.0.0/17241.10.0.1 to 241.10.127.254241.10.127.25532,766
22241.10.128.0/17241.10.128.1 to 241.10.255.254241.10.255.25532,766
23241.11.0.0/17241.11.0.1 to 241.11.127.254241.11.127.25532,766
24241.11.128.0/17241.11.128.1 to 241.11.255.254241.11.255.25532,766
25241.12.0.0/17241.12.0.1 to 241.12.127.254241.12.127.25532,766
26241.12.128.0/17241.12.128.1 to 241.12.255.254241.12.255.25532,766
27241.13.0.0/17241.13.0.1 to 241.13.127.254241.13.127.25532,766
28241.13.128.0/17241.13.128.1 to 241.13.255.254241.13.255.25532,766
29241.14.0.0/17241.14.0.1 to 241.14.127.254241.14.127.25532,766
30241.14.128.0/17241.14.128.1 to 241.14.255.254241.14.255.25532,766
31241.15.0.0/17241.15.0.1 to 241.15.127.254241.15.127.25532,766
32241.15.128.0/17241.15.128.1 to 241.15.255.254241.15.255.25532,766
33241.16.0.0/17241.16.0.1 to 241.16.127.254241.16.127.25532,766
34241.16.128.0/17241.16.128.1 to 241.16.255.254241.16.255.25532,766
35241.17.0.0/17241.17.0.1 to 241.17.127.254241.17.127.25532,766
36241.17.128.0/17241.17.128.1 to 241.17.255.254241.17.255.25532,766
37241.18.0.0/17241.18.0.1 to 241.18.127.254241.18.127.25532,766
38241.18.128.0/17241.18.128.1 to 241.18.255.254241.18.255.25532,766
39241.19.0.0/17241.19.0.1 to 241.19.127.254241.19.127.25532,766
40241.19.128.0/17241.19.128.1 to 241.19.255.254241.19.255.25532,766
41241.20.0.0/17241.20.0.1 to 241.20.127.254241.20.127.25532,766
42241.20.128.0/17241.20.128.1 to 241.20.255.254241.20.255.25532,766
43241.21.0.0/17241.21.0.1 to 241.21.127.254241.21.127.25532,766
44241.21.128.0/17241.21.128.1 to 241.21.255.254241.21.255.25532,766
45241.22.0.0/17241.22.0.1 to 241.22.127.254241.22.127.25532,766
46241.22.128.0/17241.22.128.1 to 241.22.255.254241.22.255.25532,766
47241.23.0.0/17241.23.0.1 to 241.23.127.254241.23.127.25532,766
48241.23.128.0/17241.23.128.1 to 241.23.255.254241.23.255.25532,766
49241.24.0.0/17241.24.0.1 to 241.24.127.254241.24.127.25532,766
50241.24.128.0/17241.24.128.1 to 241.24.255.254241.24.255.25532,766
51241.25.0.0/17241.25.0.1 to 241.25.127.254241.25.127.25532,766
52241.25.128.0/17241.25.128.1 to 241.25.255.254241.25.255.25532,766
53241.26.0.0/17241.26.0.1 to 241.26.127.254241.26.127.25532,766
54241.26.128.0/17241.26.128.1 to 241.26.255.254241.26.255.25532,766
55241.27.0.0/17241.27.0.1 to 241.27.127.254241.27.127.25532,766
56241.27.128.0/17241.27.128.1 to 241.27.255.254241.27.255.25532,766
57241.28.0.0/17241.28.0.1 to 241.28.127.254241.28.127.25532,766
58241.28.128.0/17241.28.128.1 to 241.28.255.254241.28.255.25532,766
59241.29.0.0/17241.29.0.1 to 241.29.127.254241.29.127.25532,766
60241.29.128.0/17241.29.128.1 to 241.29.255.254241.29.255.25532,766
61241.30.0.0/17241.30.0.1 to 241.30.127.254241.30.127.25532,766
62241.30.128.0/17241.30.128.1 to 241.30.255.254241.30.255.25532,766
63241.31.0.0/17241.31.0.1 to 241.31.127.254241.31.127.25532,766
64241.31.128.0/17241.31.128.1 to 241.31.255.254241.31.255.25532,766
65241.32.0.0/17241.32.0.1 to 241.32.127.254241.32.127.25532,766
66241.32.128.0/17241.32.128.1 to 241.32.255.254241.32.255.25532,766
67241.33.0.0/17241.33.0.1 to 241.33.127.254241.33.127.25532,766
68241.33.128.0/17241.33.128.1 to 241.33.255.254241.33.255.25532,766
69241.34.0.0/17241.34.0.1 to 241.34.127.254241.34.127.25532,766
70241.34.128.0/17241.34.128.1 to 241.34.255.254241.34.255.25532,766
71241.35.0.0/17241.35.0.1 to 241.35.127.254241.35.127.25532,766
72241.35.128.0/17241.35.128.1 to 241.35.255.254241.35.255.25532,766
73241.36.0.0/17241.36.0.1 to 241.36.127.254241.36.127.25532,766
74241.36.128.0/17241.36.128.1 to 241.36.255.254241.36.255.25532,766
75241.37.0.0/17241.37.0.1 to 241.37.127.254241.37.127.25532,766
76241.37.128.0/17241.37.128.1 to 241.37.255.254241.37.255.25532,766
77241.38.0.0/17241.38.0.1 to 241.38.127.254241.38.127.25532,766
78241.38.128.0/17241.38.128.1 to 241.38.255.254241.38.255.25532,766
79241.39.0.0/17241.39.0.1 to 241.39.127.254241.39.127.25532,766
80241.39.128.0/17241.39.128.1 to 241.39.255.254241.39.255.25532,766
81241.40.0.0/17241.40.0.1 to 241.40.127.254241.40.127.25532,766
82241.40.128.0/17241.40.128.1 to 241.40.255.254241.40.255.25532,766
83241.41.0.0/17241.41.0.1 to 241.41.127.254241.41.127.25532,766
84241.41.128.0/17241.41.128.1 to 241.41.255.254241.41.255.25532,766
85241.42.0.0/17241.42.0.1 to 241.42.127.254241.42.127.25532,766
86241.42.128.0/17241.42.128.1 to 241.42.255.254241.42.255.25532,766
87241.43.0.0/17241.43.0.1 to 241.43.127.254241.43.127.25532,766
88241.43.128.0/17241.43.128.1 to 241.43.255.254241.43.255.25532,766
89241.44.0.0/17241.44.0.1 to 241.44.127.254241.44.127.25532,766
90241.44.128.0/17241.44.128.1 to 241.44.255.254241.44.255.25532,766
91241.45.0.0/17241.45.0.1 to 241.45.127.254241.45.127.25532,766
92241.45.128.0/17241.45.128.1 to 241.45.255.254241.45.255.25532,766
93241.46.0.0/17241.46.0.1 to 241.46.127.254241.46.127.25532,766
94241.46.128.0/17241.46.128.1 to 241.46.255.254241.46.255.25532,766
95241.47.0.0/17241.47.0.1 to 241.47.127.254241.47.127.25532,766
96241.47.128.0/17241.47.128.1 to 241.47.255.254241.47.255.25532,766
97241.48.0.0/17241.48.0.1 to 241.48.127.254241.48.127.25532,766
98241.48.128.0/17241.48.128.1 to 241.48.255.254241.48.255.25532,766
99241.49.0.0/17241.49.0.1 to 241.49.127.254241.49.127.25532,766
100241.49.128.0/17241.49.128.1 to 241.49.255.254241.49.255.25532,766
101241.50.0.0/17241.50.0.1 to 241.50.127.254241.50.127.25532,766
102241.50.128.0/17241.50.128.1 to 241.50.255.254241.50.255.25532,766
103241.51.0.0/17241.51.0.1 to 241.51.127.254241.51.127.25532,766
104241.51.128.0/17241.51.128.1 to 241.51.255.254241.51.255.25532,766
105241.52.0.0/17241.52.0.1 to 241.52.127.254241.52.127.25532,766
106241.52.128.0/17241.52.128.1 to 241.52.255.254241.52.255.25532,766
107241.53.0.0/17241.53.0.1 to 241.53.127.254241.53.127.25532,766
108241.53.128.0/17241.53.128.1 to 241.53.255.254241.53.255.25532,766
109241.54.0.0/17241.54.0.1 to 241.54.127.254241.54.127.25532,766
110241.54.128.0/17241.54.128.1 to 241.54.255.254241.54.255.25532,766
111241.55.0.0/17241.55.0.1 to 241.55.127.254241.55.127.25532,766
112241.55.128.0/17241.55.128.1 to 241.55.255.254241.55.255.25532,766
113241.56.0.0/17241.56.0.1 to 241.56.127.254241.56.127.25532,766
114241.56.128.0/17241.56.128.1 to 241.56.255.254241.56.255.25532,766
115241.57.0.0/17241.57.0.1 to 241.57.127.254241.57.127.25532,766
116241.57.128.0/17241.57.128.1 to 241.57.255.254241.57.255.25532,766
117241.58.0.0/17241.58.0.1 to 241.58.127.254241.58.127.25532,766
118241.58.128.0/17241.58.128.1 to 241.58.255.254241.58.255.25532,766
119241.59.0.0/17241.59.0.1 to 241.59.127.254241.59.127.25532,766
120241.59.128.0/17241.59.128.1 to 241.59.255.254241.59.255.25532,766
121241.60.0.0/17241.60.0.1 to 241.60.127.254241.60.127.25532,766
122241.60.128.0/17241.60.128.1 to 241.60.255.254241.60.255.25532,766
123241.61.0.0/17241.61.0.1 to 241.61.127.254241.61.127.25532,766
124241.61.128.0/17241.61.128.1 to 241.61.255.254241.61.255.25532,766
125241.62.0.0/17241.62.0.1 to 241.62.127.254241.62.127.25532,766
126241.62.128.0/17241.62.128.1 to 241.62.255.254241.62.255.25532,766
127241.63.0.0/17241.63.0.1 to 241.63.127.254241.63.127.25532,766
128241.63.128.0/17241.63.128.1 to 241.63.255.254241.63.255.25532,766

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.