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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.

Network245.192.0.0/10
Usable hosts4,194,302
Subnet mask255.192.0.0
Addresses4,194,304
Network address
245.192.0.0
Broadcast address
245.255.255.255
First usable
245.192.0.1
Last usable
245.255.255.254
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 F5C00000 · Integer 4123000832 to 4127195135
Reverse DNS zones
192.245.in-addr.arpa
193.245.in-addr.arpa
194.245.in-addr.arpa
195.245.in-addr.arpa
196.245.in-addr.arpa
197.245.in-addr.arpa
198.245.in-addr.arpa
199.245.in-addr.arpa
200.245.in-addr.arpa
201.245.in-addr.arpa
202.245.in-addr.arpa
203.245.in-addr.arpa
204.245.in-addr.arpa
205.245.in-addr.arpa
206.245.in-addr.arpa
207.245.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
Address11110101.11000000.00000000.00000000245.192.0.0
Subnet mask11111111.11000000.00000000.00000000255.192.0.0
Network11110101.11000000.00000000.00000000245.192.0.0
Broadcast11110101.11111111.11111111.11111111245.255.255.255
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)

245.192.0.0/10 makes 128 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1245.192.0.0/17245.192.0.1 to 245.192.127.254245.192.127.25532,766
2245.192.128.0/17245.192.128.1 to 245.192.255.254245.192.255.25532,766
3245.193.0.0/17245.193.0.1 to 245.193.127.254245.193.127.25532,766
4245.193.128.0/17245.193.128.1 to 245.193.255.254245.193.255.25532,766
5245.194.0.0/17245.194.0.1 to 245.194.127.254245.194.127.25532,766
6245.194.128.0/17245.194.128.1 to 245.194.255.254245.194.255.25532,766
7245.195.0.0/17245.195.0.1 to 245.195.127.254245.195.127.25532,766
8245.195.128.0/17245.195.128.1 to 245.195.255.254245.195.255.25532,766
9245.196.0.0/17245.196.0.1 to 245.196.127.254245.196.127.25532,766
10245.196.128.0/17245.196.128.1 to 245.196.255.254245.196.255.25532,766
11245.197.0.0/17245.197.0.1 to 245.197.127.254245.197.127.25532,766
12245.197.128.0/17245.197.128.1 to 245.197.255.254245.197.255.25532,766
13245.198.0.0/17245.198.0.1 to 245.198.127.254245.198.127.25532,766
14245.198.128.0/17245.198.128.1 to 245.198.255.254245.198.255.25532,766
15245.199.0.0/17245.199.0.1 to 245.199.127.254245.199.127.25532,766
16245.199.128.0/17245.199.128.1 to 245.199.255.254245.199.255.25532,766
17245.200.0.0/17245.200.0.1 to 245.200.127.254245.200.127.25532,766
18245.200.128.0/17245.200.128.1 to 245.200.255.254245.200.255.25532,766
19245.201.0.0/17245.201.0.1 to 245.201.127.254245.201.127.25532,766
20245.201.128.0/17245.201.128.1 to 245.201.255.254245.201.255.25532,766
21245.202.0.0/17245.202.0.1 to 245.202.127.254245.202.127.25532,766
22245.202.128.0/17245.202.128.1 to 245.202.255.254245.202.255.25532,766
23245.203.0.0/17245.203.0.1 to 245.203.127.254245.203.127.25532,766
24245.203.128.0/17245.203.128.1 to 245.203.255.254245.203.255.25532,766
25245.204.0.0/17245.204.0.1 to 245.204.127.254245.204.127.25532,766
26245.204.128.0/17245.204.128.1 to 245.204.255.254245.204.255.25532,766
27245.205.0.0/17245.205.0.1 to 245.205.127.254245.205.127.25532,766
28245.205.128.0/17245.205.128.1 to 245.205.255.254245.205.255.25532,766
29245.206.0.0/17245.206.0.1 to 245.206.127.254245.206.127.25532,766
30245.206.128.0/17245.206.128.1 to 245.206.255.254245.206.255.25532,766
31245.207.0.0/17245.207.0.1 to 245.207.127.254245.207.127.25532,766
32245.207.128.0/17245.207.128.1 to 245.207.255.254245.207.255.25532,766
33245.208.0.0/17245.208.0.1 to 245.208.127.254245.208.127.25532,766
34245.208.128.0/17245.208.128.1 to 245.208.255.254245.208.255.25532,766
35245.209.0.0/17245.209.0.1 to 245.209.127.254245.209.127.25532,766
36245.209.128.0/17245.209.128.1 to 245.209.255.254245.209.255.25532,766
37245.210.0.0/17245.210.0.1 to 245.210.127.254245.210.127.25532,766
38245.210.128.0/17245.210.128.1 to 245.210.255.254245.210.255.25532,766
39245.211.0.0/17245.211.0.1 to 245.211.127.254245.211.127.25532,766
40245.211.128.0/17245.211.128.1 to 245.211.255.254245.211.255.25532,766
41245.212.0.0/17245.212.0.1 to 245.212.127.254245.212.127.25532,766
42245.212.128.0/17245.212.128.1 to 245.212.255.254245.212.255.25532,766
43245.213.0.0/17245.213.0.1 to 245.213.127.254245.213.127.25532,766
44245.213.128.0/17245.213.128.1 to 245.213.255.254245.213.255.25532,766
45245.214.0.0/17245.214.0.1 to 245.214.127.254245.214.127.25532,766
46245.214.128.0/17245.214.128.1 to 245.214.255.254245.214.255.25532,766
47245.215.0.0/17245.215.0.1 to 245.215.127.254245.215.127.25532,766
48245.215.128.0/17245.215.128.1 to 245.215.255.254245.215.255.25532,766
49245.216.0.0/17245.216.0.1 to 245.216.127.254245.216.127.25532,766
50245.216.128.0/17245.216.128.1 to 245.216.255.254245.216.255.25532,766
51245.217.0.0/17245.217.0.1 to 245.217.127.254245.217.127.25532,766
52245.217.128.0/17245.217.128.1 to 245.217.255.254245.217.255.25532,766
53245.218.0.0/17245.218.0.1 to 245.218.127.254245.218.127.25532,766
54245.218.128.0/17245.218.128.1 to 245.218.255.254245.218.255.25532,766
55245.219.0.0/17245.219.0.1 to 245.219.127.254245.219.127.25532,766
56245.219.128.0/17245.219.128.1 to 245.219.255.254245.219.255.25532,766
57245.220.0.0/17245.220.0.1 to 245.220.127.254245.220.127.25532,766
58245.220.128.0/17245.220.128.1 to 245.220.255.254245.220.255.25532,766
59245.221.0.0/17245.221.0.1 to 245.221.127.254245.221.127.25532,766
60245.221.128.0/17245.221.128.1 to 245.221.255.254245.221.255.25532,766
61245.222.0.0/17245.222.0.1 to 245.222.127.254245.222.127.25532,766
62245.222.128.0/17245.222.128.1 to 245.222.255.254245.222.255.25532,766
63245.223.0.0/17245.223.0.1 to 245.223.127.254245.223.127.25532,766
64245.223.128.0/17245.223.128.1 to 245.223.255.254245.223.255.25532,766
65245.224.0.0/17245.224.0.1 to 245.224.127.254245.224.127.25532,766
66245.224.128.0/17245.224.128.1 to 245.224.255.254245.224.255.25532,766
67245.225.0.0/17245.225.0.1 to 245.225.127.254245.225.127.25532,766
68245.225.128.0/17245.225.128.1 to 245.225.255.254245.225.255.25532,766
69245.226.0.0/17245.226.0.1 to 245.226.127.254245.226.127.25532,766
70245.226.128.0/17245.226.128.1 to 245.226.255.254245.226.255.25532,766
71245.227.0.0/17245.227.0.1 to 245.227.127.254245.227.127.25532,766
72245.227.128.0/17245.227.128.1 to 245.227.255.254245.227.255.25532,766
73245.228.0.0/17245.228.0.1 to 245.228.127.254245.228.127.25532,766
74245.228.128.0/17245.228.128.1 to 245.228.255.254245.228.255.25532,766
75245.229.0.0/17245.229.0.1 to 245.229.127.254245.229.127.25532,766
76245.229.128.0/17245.229.128.1 to 245.229.255.254245.229.255.25532,766
77245.230.0.0/17245.230.0.1 to 245.230.127.254245.230.127.25532,766
78245.230.128.0/17245.230.128.1 to 245.230.255.254245.230.255.25532,766
79245.231.0.0/17245.231.0.1 to 245.231.127.254245.231.127.25532,766
80245.231.128.0/17245.231.128.1 to 245.231.255.254245.231.255.25532,766
81245.232.0.0/17245.232.0.1 to 245.232.127.254245.232.127.25532,766
82245.232.128.0/17245.232.128.1 to 245.232.255.254245.232.255.25532,766
83245.233.0.0/17245.233.0.1 to 245.233.127.254245.233.127.25532,766
84245.233.128.0/17245.233.128.1 to 245.233.255.254245.233.255.25532,766
85245.234.0.0/17245.234.0.1 to 245.234.127.254245.234.127.25532,766
86245.234.128.0/17245.234.128.1 to 245.234.255.254245.234.255.25532,766
87245.235.0.0/17245.235.0.1 to 245.235.127.254245.235.127.25532,766
88245.235.128.0/17245.235.128.1 to 245.235.255.254245.235.255.25532,766
89245.236.0.0/17245.236.0.1 to 245.236.127.254245.236.127.25532,766
90245.236.128.0/17245.236.128.1 to 245.236.255.254245.236.255.25532,766
91245.237.0.0/17245.237.0.1 to 245.237.127.254245.237.127.25532,766
92245.237.128.0/17245.237.128.1 to 245.237.255.254245.237.255.25532,766
93245.238.0.0/17245.238.0.1 to 245.238.127.254245.238.127.25532,766
94245.238.128.0/17245.238.128.1 to 245.238.255.254245.238.255.25532,766
95245.239.0.0/17245.239.0.1 to 245.239.127.254245.239.127.25532,766
96245.239.128.0/17245.239.128.1 to 245.239.255.254245.239.255.25532,766
97245.240.0.0/17245.240.0.1 to 245.240.127.254245.240.127.25532,766
98245.240.128.0/17245.240.128.1 to 245.240.255.254245.240.255.25532,766
99245.241.0.0/17245.241.0.1 to 245.241.127.254245.241.127.25532,766
100245.241.128.0/17245.241.128.1 to 245.241.255.254245.241.255.25532,766
101245.242.0.0/17245.242.0.1 to 245.242.127.254245.242.127.25532,766
102245.242.128.0/17245.242.128.1 to 245.242.255.254245.242.255.25532,766
103245.243.0.0/17245.243.0.1 to 245.243.127.254245.243.127.25532,766
104245.243.128.0/17245.243.128.1 to 245.243.255.254245.243.255.25532,766
105245.244.0.0/17245.244.0.1 to 245.244.127.254245.244.127.25532,766
106245.244.128.0/17245.244.128.1 to 245.244.255.254245.244.255.25532,766
107245.245.0.0/17245.245.0.1 to 245.245.127.254245.245.127.25532,766
108245.245.128.0/17245.245.128.1 to 245.245.255.254245.245.255.25532,766
109245.246.0.0/17245.246.0.1 to 245.246.127.254245.246.127.25532,766
110245.246.128.0/17245.246.128.1 to 245.246.255.254245.246.255.25532,766
111245.247.0.0/17245.247.0.1 to 245.247.127.254245.247.127.25532,766
112245.247.128.0/17245.247.128.1 to 245.247.255.254245.247.255.25532,766
113245.248.0.0/17245.248.0.1 to 245.248.127.254245.248.127.25532,766
114245.248.128.0/17245.248.128.1 to 245.248.255.254245.248.255.25532,766
115245.249.0.0/17245.249.0.1 to 245.249.127.254245.249.127.25532,766
116245.249.128.0/17245.249.128.1 to 245.249.255.254245.249.255.25532,766
117245.250.0.0/17245.250.0.1 to 245.250.127.254245.250.127.25532,766
118245.250.128.0/17245.250.128.1 to 245.250.255.254245.250.255.25532,766
119245.251.0.0/17245.251.0.1 to 245.251.127.254245.251.127.25532,766
120245.251.128.0/17245.251.128.1 to 245.251.255.254245.251.255.25532,766
121245.252.0.0/17245.252.0.1 to 245.252.127.254245.252.127.25532,766
122245.252.128.0/17245.252.128.1 to 245.252.255.254245.252.255.25532,766
123245.253.0.0/17245.253.0.1 to 245.253.127.254245.253.127.25532,766
124245.253.128.0/17245.253.128.1 to 245.253.255.254245.253.255.25532,766
125245.254.0.0/17245.254.0.1 to 245.254.127.254245.254.127.25532,766
126245.254.128.0/17245.254.128.1 to 245.254.255.254245.254.255.25532,766
127245.255.0.0/17245.255.0.1 to 245.255.127.254245.255.127.25532,766
128245.255.128.0/17245.255.128.1 to 245.255.255.254245.255.255.25532,766

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.