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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.

Network253.97.2.0/23
Usable hosts510
Subnet mask255.255.254.0
Addresses512
Network address
253.97.2.0
Broadcast address
253.97.3.255
First usable
253.97.2.1
Last usable
253.97.3.254
Usable hosts
510 (512 less the network and broadcast addresses)
Subnet mask
255.255.254.0
Wildcard mask
0.0.1.255 (Cisco ACLs, OSPF)
Prefix length
/23
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex FD610200 · Integer 4250993152 to 4250993663
Reverse DNS zones
2.97.253.in-addr.arpa
3.97.253.in-addr.arpa
/23 is not on a 8-bit boundary, so it takes 2 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11111101.01100001.00000010.00000000253.97.2.0
Subnet mask11111111.11111111.11111110.00000000255.255.254.0
Network11111101.01100001.00000010.00000000253.97.2.0
Broadcast11111101.01100001.00000011.11111111253.97.3.255
Split into smaller subnets/30
/24 (2)/25 (4)/26 (8)/27 (16)/28 (32)/29 (64)/30 (128)/31 (256)/32 (512)

253.97.2.0/23 makes 128 subnets of /30.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1253.97.2.0/30253.97.2.1 to 253.97.2.2253.97.2.32
2253.97.2.4/30253.97.2.5 to 253.97.2.6253.97.2.72
3253.97.2.8/30253.97.2.9 to 253.97.2.10253.97.2.112
4253.97.2.12/30253.97.2.13 to 253.97.2.14253.97.2.152
5253.97.2.16/30253.97.2.17 to 253.97.2.18253.97.2.192
6253.97.2.20/30253.97.2.21 to 253.97.2.22253.97.2.232
7253.97.2.24/30253.97.2.25 to 253.97.2.26253.97.2.272
8253.97.2.28/30253.97.2.29 to 253.97.2.30253.97.2.312
9253.97.2.32/30253.97.2.33 to 253.97.2.34253.97.2.352
10253.97.2.36/30253.97.2.37 to 253.97.2.38253.97.2.392
11253.97.2.40/30253.97.2.41 to 253.97.2.42253.97.2.432
12253.97.2.44/30253.97.2.45 to 253.97.2.46253.97.2.472
13253.97.2.48/30253.97.2.49 to 253.97.2.50253.97.2.512
14253.97.2.52/30253.97.2.53 to 253.97.2.54253.97.2.552
15253.97.2.56/30253.97.2.57 to 253.97.2.58253.97.2.592
16253.97.2.60/30253.97.2.61 to 253.97.2.62253.97.2.632
17253.97.2.64/30253.97.2.65 to 253.97.2.66253.97.2.672
18253.97.2.68/30253.97.2.69 to 253.97.2.70253.97.2.712
19253.97.2.72/30253.97.2.73 to 253.97.2.74253.97.2.752
20253.97.2.76/30253.97.2.77 to 253.97.2.78253.97.2.792
21253.97.2.80/30253.97.2.81 to 253.97.2.82253.97.2.832
22253.97.2.84/30253.97.2.85 to 253.97.2.86253.97.2.872
23253.97.2.88/30253.97.2.89 to 253.97.2.90253.97.2.912
24253.97.2.92/30253.97.2.93 to 253.97.2.94253.97.2.952
25253.97.2.96/30253.97.2.97 to 253.97.2.98253.97.2.992
26253.97.2.100/30253.97.2.101 to 253.97.2.102253.97.2.1032
27253.97.2.104/30253.97.2.105 to 253.97.2.106253.97.2.1072
28253.97.2.108/30253.97.2.109 to 253.97.2.110253.97.2.1112
29253.97.2.112/30253.97.2.113 to 253.97.2.114253.97.2.1152
30253.97.2.116/30253.97.2.117 to 253.97.2.118253.97.2.1192
31253.97.2.120/30253.97.2.121 to 253.97.2.122253.97.2.1232
32253.97.2.124/30253.97.2.125 to 253.97.2.126253.97.2.1272
33253.97.2.128/30253.97.2.129 to 253.97.2.130253.97.2.1312
34253.97.2.132/30253.97.2.133 to 253.97.2.134253.97.2.1352
35253.97.2.136/30253.97.2.137 to 253.97.2.138253.97.2.1392
36253.97.2.140/30253.97.2.141 to 253.97.2.142253.97.2.1432
37253.97.2.144/30253.97.2.145 to 253.97.2.146253.97.2.1472
38253.97.2.148/30253.97.2.149 to 253.97.2.150253.97.2.1512
39253.97.2.152/30253.97.2.153 to 253.97.2.154253.97.2.1552
40253.97.2.156/30253.97.2.157 to 253.97.2.158253.97.2.1592
41253.97.2.160/30253.97.2.161 to 253.97.2.162253.97.2.1632
42253.97.2.164/30253.97.2.165 to 253.97.2.166253.97.2.1672
43253.97.2.168/30253.97.2.169 to 253.97.2.170253.97.2.1712
44253.97.2.172/30253.97.2.173 to 253.97.2.174253.97.2.1752
45253.97.2.176/30253.97.2.177 to 253.97.2.178253.97.2.1792
46253.97.2.180/30253.97.2.181 to 253.97.2.182253.97.2.1832
47253.97.2.184/30253.97.2.185 to 253.97.2.186253.97.2.1872
48253.97.2.188/30253.97.2.189 to 253.97.2.190253.97.2.1912
49253.97.2.192/30253.97.2.193 to 253.97.2.194253.97.2.1952
50253.97.2.196/30253.97.2.197 to 253.97.2.198253.97.2.1992
51253.97.2.200/30253.97.2.201 to 253.97.2.202253.97.2.2032
52253.97.2.204/30253.97.2.205 to 253.97.2.206253.97.2.2072
53253.97.2.208/30253.97.2.209 to 253.97.2.210253.97.2.2112
54253.97.2.212/30253.97.2.213 to 253.97.2.214253.97.2.2152
55253.97.2.216/30253.97.2.217 to 253.97.2.218253.97.2.2192
56253.97.2.220/30253.97.2.221 to 253.97.2.222253.97.2.2232
57253.97.2.224/30253.97.2.225 to 253.97.2.226253.97.2.2272
58253.97.2.228/30253.97.2.229 to 253.97.2.230253.97.2.2312
59253.97.2.232/30253.97.2.233 to 253.97.2.234253.97.2.2352
60253.97.2.236/30253.97.2.237 to 253.97.2.238253.97.2.2392
61253.97.2.240/30253.97.2.241 to 253.97.2.242253.97.2.2432
62253.97.2.244/30253.97.2.245 to 253.97.2.246253.97.2.2472
63253.97.2.248/30253.97.2.249 to 253.97.2.250253.97.2.2512
64253.97.2.252/30253.97.2.253 to 253.97.2.254253.97.2.2552
65253.97.3.0/30253.97.3.1 to 253.97.3.2253.97.3.32
66253.97.3.4/30253.97.3.5 to 253.97.3.6253.97.3.72
67253.97.3.8/30253.97.3.9 to 253.97.3.10253.97.3.112
68253.97.3.12/30253.97.3.13 to 253.97.3.14253.97.3.152
69253.97.3.16/30253.97.3.17 to 253.97.3.18253.97.3.192
70253.97.3.20/30253.97.3.21 to 253.97.3.22253.97.3.232
71253.97.3.24/30253.97.3.25 to 253.97.3.26253.97.3.272
72253.97.3.28/30253.97.3.29 to 253.97.3.30253.97.3.312
73253.97.3.32/30253.97.3.33 to 253.97.3.34253.97.3.352
74253.97.3.36/30253.97.3.37 to 253.97.3.38253.97.3.392
75253.97.3.40/30253.97.3.41 to 253.97.3.42253.97.3.432
76253.97.3.44/30253.97.3.45 to 253.97.3.46253.97.3.472
77253.97.3.48/30253.97.3.49 to 253.97.3.50253.97.3.512
78253.97.3.52/30253.97.3.53 to 253.97.3.54253.97.3.552
79253.97.3.56/30253.97.3.57 to 253.97.3.58253.97.3.592
80253.97.3.60/30253.97.3.61 to 253.97.3.62253.97.3.632
81253.97.3.64/30253.97.3.65 to 253.97.3.66253.97.3.672
82253.97.3.68/30253.97.3.69 to 253.97.3.70253.97.3.712
83253.97.3.72/30253.97.3.73 to 253.97.3.74253.97.3.752
84253.97.3.76/30253.97.3.77 to 253.97.3.78253.97.3.792
85253.97.3.80/30253.97.3.81 to 253.97.3.82253.97.3.832
86253.97.3.84/30253.97.3.85 to 253.97.3.86253.97.3.872
87253.97.3.88/30253.97.3.89 to 253.97.3.90253.97.3.912
88253.97.3.92/30253.97.3.93 to 253.97.3.94253.97.3.952
89253.97.3.96/30253.97.3.97 to 253.97.3.98253.97.3.992
90253.97.3.100/30253.97.3.101 to 253.97.3.102253.97.3.1032
91253.97.3.104/30253.97.3.105 to 253.97.3.106253.97.3.1072
92253.97.3.108/30253.97.3.109 to 253.97.3.110253.97.3.1112
93253.97.3.112/30253.97.3.113 to 253.97.3.114253.97.3.1152
94253.97.3.116/30253.97.3.117 to 253.97.3.118253.97.3.1192
95253.97.3.120/30253.97.3.121 to 253.97.3.122253.97.3.1232
96253.97.3.124/30253.97.3.125 to 253.97.3.126253.97.3.1272
97253.97.3.128/30253.97.3.129 to 253.97.3.130253.97.3.1312
98253.97.3.132/30253.97.3.133 to 253.97.3.134253.97.3.1352
99253.97.3.136/30253.97.3.137 to 253.97.3.138253.97.3.1392
100253.97.3.140/30253.97.3.141 to 253.97.3.142253.97.3.1432
101253.97.3.144/30253.97.3.145 to 253.97.3.146253.97.3.1472
102253.97.3.148/30253.97.3.149 to 253.97.3.150253.97.3.1512
103253.97.3.152/30253.97.3.153 to 253.97.3.154253.97.3.1552
104253.97.3.156/30253.97.3.157 to 253.97.3.158253.97.3.1592
105253.97.3.160/30253.97.3.161 to 253.97.3.162253.97.3.1632
106253.97.3.164/30253.97.3.165 to 253.97.3.166253.97.3.1672
107253.97.3.168/30253.97.3.169 to 253.97.3.170253.97.3.1712
108253.97.3.172/30253.97.3.173 to 253.97.3.174253.97.3.1752
109253.97.3.176/30253.97.3.177 to 253.97.3.178253.97.3.1792
110253.97.3.180/30253.97.3.181 to 253.97.3.182253.97.3.1832
111253.97.3.184/30253.97.3.185 to 253.97.3.186253.97.3.1872
112253.97.3.188/30253.97.3.189 to 253.97.3.190253.97.3.1912
113253.97.3.192/30253.97.3.193 to 253.97.3.194253.97.3.1952
114253.97.3.196/30253.97.3.197 to 253.97.3.198253.97.3.1992
115253.97.3.200/30253.97.3.201 to 253.97.3.202253.97.3.2032
116253.97.3.204/30253.97.3.205 to 253.97.3.206253.97.3.2072
117253.97.3.208/30253.97.3.209 to 253.97.3.210253.97.3.2112
118253.97.3.212/30253.97.3.213 to 253.97.3.214253.97.3.2152
119253.97.3.216/30253.97.3.217 to 253.97.3.218253.97.3.2192
120253.97.3.220/30253.97.3.221 to 253.97.3.222253.97.3.2232
121253.97.3.224/30253.97.3.225 to 253.97.3.226253.97.3.2272
122253.97.3.228/30253.97.3.229 to 253.97.3.230253.97.3.2312
123253.97.3.232/30253.97.3.233 to 253.97.3.234253.97.3.2352
124253.97.3.236/30253.97.3.237 to 253.97.3.238253.97.3.2392
125253.97.3.240/30253.97.3.241 to 253.97.3.242253.97.3.2432
126253.97.3.244/30253.97.3.245 to 253.97.3.246253.97.3.2472
127253.97.3.248/30253.97.3.249 to 253.97.3.250253.97.3.2512
128253.97.3.252/30253.97.3.253 to 253.97.3.254253.97.3.2552

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.