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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.

Prefix/17
Addresses2^111
/64 networks2^47
Network
ffd7::/17
First address
ffd7::
Last address
ffd7:7fff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
2,596,148,429,267,413,814,265,248,164,610,048 (2^111)
/64 networks (LANs)
140,737,488,355,328 (2^47)
Full form
ffd7:0000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zones
0.7.d.f.f.ip6.arpa
1.7.d.f.f.ip6.arpa
2.7.d.f.f.ip6.arpa
3.7.d.f.f.ip6.arpa
4.7.d.f.f.ip6.arpa
5.7.d.f.f.ip6.arpa
6.7.d.f.f.ip6.arpa
7.7.d.f.f.ip6.arpa
/17 is not on a 4-bit boundary, so it takes 8 /20 zones.
Split into smaller subnets/24
/18 (2)/19 (4)/20 (8)/21 (16)/24 (128)/28 (2,048)/32 (32,768)

ffd7::/17 makes 128 subnets of /24.

Subnets
#SubnetLast address
1ffd7::/24ffd7:ff:ffff:ffff:ffff:ffff:ffff:ffff
2ffd7:100::/24ffd7:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3ffd7:200::/24ffd7:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4ffd7:300::/24ffd7:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5ffd7:400::/24ffd7:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6ffd7:500::/24ffd7:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7ffd7:600::/24ffd7:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8ffd7:700::/24ffd7:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9ffd7:800::/24ffd7:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10ffd7:900::/24ffd7:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11ffd7:a00::/24ffd7:aff:ffff:ffff:ffff:ffff:ffff:ffff
12ffd7:b00::/24ffd7:bff:ffff:ffff:ffff:ffff:ffff:ffff
13ffd7:c00::/24ffd7:cff:ffff:ffff:ffff:ffff:ffff:ffff
14ffd7:d00::/24ffd7:dff:ffff:ffff:ffff:ffff:ffff:ffff
15ffd7:e00::/24ffd7:eff:ffff:ffff:ffff:ffff:ffff:ffff
16ffd7:f00::/24ffd7:fff:ffff:ffff:ffff:ffff:ffff:ffff
17ffd7:1000::/24ffd7:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18ffd7:1100::/24ffd7:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19ffd7:1200::/24ffd7:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20ffd7:1300::/24ffd7:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21ffd7:1400::/24ffd7:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22ffd7:1500::/24ffd7:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23ffd7:1600::/24ffd7:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24ffd7:1700::/24ffd7:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25ffd7:1800::/24ffd7:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26ffd7:1900::/24ffd7:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27ffd7:1a00::/24ffd7:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28ffd7:1b00::/24ffd7:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29ffd7:1c00::/24ffd7:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30ffd7:1d00::/24ffd7:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31ffd7:1e00::/24ffd7:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32ffd7:1f00::/24ffd7:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33ffd7:2000::/24ffd7:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34ffd7:2100::/24ffd7:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35ffd7:2200::/24ffd7:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36ffd7:2300::/24ffd7:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37ffd7:2400::/24ffd7:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38ffd7:2500::/24ffd7:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39ffd7:2600::/24ffd7:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40ffd7:2700::/24ffd7:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41ffd7:2800::/24ffd7:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42ffd7:2900::/24ffd7:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43ffd7:2a00::/24ffd7:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44ffd7:2b00::/24ffd7:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45ffd7:2c00::/24ffd7:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46ffd7:2d00::/24ffd7:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47ffd7:2e00::/24ffd7:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48ffd7:2f00::/24ffd7:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49ffd7:3000::/24ffd7:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50ffd7:3100::/24ffd7:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51ffd7:3200::/24ffd7:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52ffd7:3300::/24ffd7:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53ffd7:3400::/24ffd7:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54ffd7:3500::/24ffd7:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55ffd7:3600::/24ffd7:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56ffd7:3700::/24ffd7:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57ffd7:3800::/24ffd7:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58ffd7:3900::/24ffd7:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59ffd7:3a00::/24ffd7:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60ffd7:3b00::/24ffd7:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61ffd7:3c00::/24ffd7:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62ffd7:3d00::/24ffd7:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63ffd7:3e00::/24ffd7:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64ffd7:3f00::/24ffd7:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65ffd7:4000::/24ffd7:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66ffd7:4100::/24ffd7:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67ffd7:4200::/24ffd7:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68ffd7:4300::/24ffd7:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69ffd7:4400::/24ffd7:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70ffd7:4500::/24ffd7:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71ffd7:4600::/24ffd7:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72ffd7:4700::/24ffd7:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73ffd7:4800::/24ffd7:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74ffd7:4900::/24ffd7:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75ffd7:4a00::/24ffd7:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76ffd7:4b00::/24ffd7:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77ffd7:4c00::/24ffd7:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78ffd7:4d00::/24ffd7:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79ffd7:4e00::/24ffd7:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80ffd7:4f00::/24ffd7:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81ffd7:5000::/24ffd7:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82ffd7:5100::/24ffd7:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83ffd7:5200::/24ffd7:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84ffd7:5300::/24ffd7:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85ffd7:5400::/24ffd7:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86ffd7:5500::/24ffd7:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87ffd7:5600::/24ffd7:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88ffd7:5700::/24ffd7:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89ffd7:5800::/24ffd7:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90ffd7:5900::/24ffd7:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91ffd7:5a00::/24ffd7:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92ffd7:5b00::/24ffd7:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93ffd7:5c00::/24ffd7:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94ffd7:5d00::/24ffd7:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95ffd7:5e00::/24ffd7:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96ffd7:5f00::/24ffd7:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97ffd7:6000::/24ffd7:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98ffd7:6100::/24ffd7:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99ffd7:6200::/24ffd7:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100ffd7:6300::/24ffd7:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101ffd7:6400::/24ffd7:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102ffd7:6500::/24ffd7:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103ffd7:6600::/24ffd7:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104ffd7:6700::/24ffd7:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105ffd7:6800::/24ffd7:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106ffd7:6900::/24ffd7:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107ffd7:6a00::/24ffd7:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108ffd7:6b00::/24ffd7:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109ffd7:6c00::/24ffd7:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110ffd7:6d00::/24ffd7:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111ffd7:6e00::/24ffd7:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112ffd7:6f00::/24ffd7:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113ffd7:7000::/24ffd7:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114ffd7:7100::/24ffd7:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115ffd7:7200::/24ffd7:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116ffd7:7300::/24ffd7:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117ffd7:7400::/24ffd7:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118ffd7:7500::/24ffd7:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119ffd7:7600::/24ffd7:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120ffd7:7700::/24ffd7:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121ffd7:7800::/24ffd7:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122ffd7:7900::/24ffd7:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123ffd7:7a00::/24ffd7:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124ffd7:7b00::/24ffd7:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125ffd7:7c00::/24ffd7:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126ffd7:7d00::/24ffd7:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127ffd7:7e00::/24ffd7:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128ffd7:7f00::/24ffd7:7fff:ffff:ffff:ffff:ffff:ffff:ffff

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.