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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.

Network222.47.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
222.47.0.0
Broadcast address
222.47.127.255
First usable
222.47.0.1
Last usable
222.47.127.254
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
Public public
Old class
C (default /24)
As numbers
Hex DE2F0000 · Integer 3727622144 to 3727654911
Reverse DNS zones
0.47.222.in-addr.arpa
1.47.222.in-addr.arpa
2.47.222.in-addr.arpa
3.47.222.in-addr.arpa
4.47.222.in-addr.arpa
5.47.222.in-addr.arpa
6.47.222.in-addr.arpa
7.47.222.in-addr.arpa
8.47.222.in-addr.arpa
9.47.222.in-addr.arpa
10.47.222.in-addr.arpa
11.47.222.in-addr.arpa
12.47.222.in-addr.arpa
13.47.222.in-addr.arpa
14.47.222.in-addr.arpa
15.47.222.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
Address11011110.00101111.00000000.00000000222.47.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network11011110.00101111.00000000.00000000222.47.0.0
Broadcast11011110.00101111.01111111.11111111222.47.127.255
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)

222.47.0.0/17 makes 128 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1222.47.0.0/24222.47.0.1 to 222.47.0.254222.47.0.255254
2222.47.1.0/24222.47.1.1 to 222.47.1.254222.47.1.255254
3222.47.2.0/24222.47.2.1 to 222.47.2.254222.47.2.255254
4222.47.3.0/24222.47.3.1 to 222.47.3.254222.47.3.255254
5222.47.4.0/24222.47.4.1 to 222.47.4.254222.47.4.255254
6222.47.5.0/24222.47.5.1 to 222.47.5.254222.47.5.255254
7222.47.6.0/24222.47.6.1 to 222.47.6.254222.47.6.255254
8222.47.7.0/24222.47.7.1 to 222.47.7.254222.47.7.255254
9222.47.8.0/24222.47.8.1 to 222.47.8.254222.47.8.255254
10222.47.9.0/24222.47.9.1 to 222.47.9.254222.47.9.255254
11222.47.10.0/24222.47.10.1 to 222.47.10.254222.47.10.255254
12222.47.11.0/24222.47.11.1 to 222.47.11.254222.47.11.255254
13222.47.12.0/24222.47.12.1 to 222.47.12.254222.47.12.255254
14222.47.13.0/24222.47.13.1 to 222.47.13.254222.47.13.255254
15222.47.14.0/24222.47.14.1 to 222.47.14.254222.47.14.255254
16222.47.15.0/24222.47.15.1 to 222.47.15.254222.47.15.255254
17222.47.16.0/24222.47.16.1 to 222.47.16.254222.47.16.255254
18222.47.17.0/24222.47.17.1 to 222.47.17.254222.47.17.255254
19222.47.18.0/24222.47.18.1 to 222.47.18.254222.47.18.255254
20222.47.19.0/24222.47.19.1 to 222.47.19.254222.47.19.255254
21222.47.20.0/24222.47.20.1 to 222.47.20.254222.47.20.255254
22222.47.21.0/24222.47.21.1 to 222.47.21.254222.47.21.255254
23222.47.22.0/24222.47.22.1 to 222.47.22.254222.47.22.255254
24222.47.23.0/24222.47.23.1 to 222.47.23.254222.47.23.255254
25222.47.24.0/24222.47.24.1 to 222.47.24.254222.47.24.255254
26222.47.25.0/24222.47.25.1 to 222.47.25.254222.47.25.255254
27222.47.26.0/24222.47.26.1 to 222.47.26.254222.47.26.255254
28222.47.27.0/24222.47.27.1 to 222.47.27.254222.47.27.255254
29222.47.28.0/24222.47.28.1 to 222.47.28.254222.47.28.255254
30222.47.29.0/24222.47.29.1 to 222.47.29.254222.47.29.255254
31222.47.30.0/24222.47.30.1 to 222.47.30.254222.47.30.255254
32222.47.31.0/24222.47.31.1 to 222.47.31.254222.47.31.255254
33222.47.32.0/24222.47.32.1 to 222.47.32.254222.47.32.255254
34222.47.33.0/24222.47.33.1 to 222.47.33.254222.47.33.255254
35222.47.34.0/24222.47.34.1 to 222.47.34.254222.47.34.255254
36222.47.35.0/24222.47.35.1 to 222.47.35.254222.47.35.255254
37222.47.36.0/24222.47.36.1 to 222.47.36.254222.47.36.255254
38222.47.37.0/24222.47.37.1 to 222.47.37.254222.47.37.255254
39222.47.38.0/24222.47.38.1 to 222.47.38.254222.47.38.255254
40222.47.39.0/24222.47.39.1 to 222.47.39.254222.47.39.255254
41222.47.40.0/24222.47.40.1 to 222.47.40.254222.47.40.255254
42222.47.41.0/24222.47.41.1 to 222.47.41.254222.47.41.255254
43222.47.42.0/24222.47.42.1 to 222.47.42.254222.47.42.255254
44222.47.43.0/24222.47.43.1 to 222.47.43.254222.47.43.255254
45222.47.44.0/24222.47.44.1 to 222.47.44.254222.47.44.255254
46222.47.45.0/24222.47.45.1 to 222.47.45.254222.47.45.255254
47222.47.46.0/24222.47.46.1 to 222.47.46.254222.47.46.255254
48222.47.47.0/24222.47.47.1 to 222.47.47.254222.47.47.255254
49222.47.48.0/24222.47.48.1 to 222.47.48.254222.47.48.255254
50222.47.49.0/24222.47.49.1 to 222.47.49.254222.47.49.255254
51222.47.50.0/24222.47.50.1 to 222.47.50.254222.47.50.255254
52222.47.51.0/24222.47.51.1 to 222.47.51.254222.47.51.255254
53222.47.52.0/24222.47.52.1 to 222.47.52.254222.47.52.255254
54222.47.53.0/24222.47.53.1 to 222.47.53.254222.47.53.255254
55222.47.54.0/24222.47.54.1 to 222.47.54.254222.47.54.255254
56222.47.55.0/24222.47.55.1 to 222.47.55.254222.47.55.255254
57222.47.56.0/24222.47.56.1 to 222.47.56.254222.47.56.255254
58222.47.57.0/24222.47.57.1 to 222.47.57.254222.47.57.255254
59222.47.58.0/24222.47.58.1 to 222.47.58.254222.47.58.255254
60222.47.59.0/24222.47.59.1 to 222.47.59.254222.47.59.255254
61222.47.60.0/24222.47.60.1 to 222.47.60.254222.47.60.255254
62222.47.61.0/24222.47.61.1 to 222.47.61.254222.47.61.255254
63222.47.62.0/24222.47.62.1 to 222.47.62.254222.47.62.255254
64222.47.63.0/24222.47.63.1 to 222.47.63.254222.47.63.255254
65222.47.64.0/24222.47.64.1 to 222.47.64.254222.47.64.255254
66222.47.65.0/24222.47.65.1 to 222.47.65.254222.47.65.255254
67222.47.66.0/24222.47.66.1 to 222.47.66.254222.47.66.255254
68222.47.67.0/24222.47.67.1 to 222.47.67.254222.47.67.255254
69222.47.68.0/24222.47.68.1 to 222.47.68.254222.47.68.255254
70222.47.69.0/24222.47.69.1 to 222.47.69.254222.47.69.255254
71222.47.70.0/24222.47.70.1 to 222.47.70.254222.47.70.255254
72222.47.71.0/24222.47.71.1 to 222.47.71.254222.47.71.255254
73222.47.72.0/24222.47.72.1 to 222.47.72.254222.47.72.255254
74222.47.73.0/24222.47.73.1 to 222.47.73.254222.47.73.255254
75222.47.74.0/24222.47.74.1 to 222.47.74.254222.47.74.255254
76222.47.75.0/24222.47.75.1 to 222.47.75.254222.47.75.255254
77222.47.76.0/24222.47.76.1 to 222.47.76.254222.47.76.255254
78222.47.77.0/24222.47.77.1 to 222.47.77.254222.47.77.255254
79222.47.78.0/24222.47.78.1 to 222.47.78.254222.47.78.255254
80222.47.79.0/24222.47.79.1 to 222.47.79.254222.47.79.255254
81222.47.80.0/24222.47.80.1 to 222.47.80.254222.47.80.255254
82222.47.81.0/24222.47.81.1 to 222.47.81.254222.47.81.255254
83222.47.82.0/24222.47.82.1 to 222.47.82.254222.47.82.255254
84222.47.83.0/24222.47.83.1 to 222.47.83.254222.47.83.255254
85222.47.84.0/24222.47.84.1 to 222.47.84.254222.47.84.255254
86222.47.85.0/24222.47.85.1 to 222.47.85.254222.47.85.255254
87222.47.86.0/24222.47.86.1 to 222.47.86.254222.47.86.255254
88222.47.87.0/24222.47.87.1 to 222.47.87.254222.47.87.255254
89222.47.88.0/24222.47.88.1 to 222.47.88.254222.47.88.255254
90222.47.89.0/24222.47.89.1 to 222.47.89.254222.47.89.255254
91222.47.90.0/24222.47.90.1 to 222.47.90.254222.47.90.255254
92222.47.91.0/24222.47.91.1 to 222.47.91.254222.47.91.255254
93222.47.92.0/24222.47.92.1 to 222.47.92.254222.47.92.255254
94222.47.93.0/24222.47.93.1 to 222.47.93.254222.47.93.255254
95222.47.94.0/24222.47.94.1 to 222.47.94.254222.47.94.255254
96222.47.95.0/24222.47.95.1 to 222.47.95.254222.47.95.255254
97222.47.96.0/24222.47.96.1 to 222.47.96.254222.47.96.255254
98222.47.97.0/24222.47.97.1 to 222.47.97.254222.47.97.255254
99222.47.98.0/24222.47.98.1 to 222.47.98.254222.47.98.255254
100222.47.99.0/24222.47.99.1 to 222.47.99.254222.47.99.255254
101222.47.100.0/24222.47.100.1 to 222.47.100.254222.47.100.255254
102222.47.101.0/24222.47.101.1 to 222.47.101.254222.47.101.255254
103222.47.102.0/24222.47.102.1 to 222.47.102.254222.47.102.255254
104222.47.103.0/24222.47.103.1 to 222.47.103.254222.47.103.255254
105222.47.104.0/24222.47.104.1 to 222.47.104.254222.47.104.255254
106222.47.105.0/24222.47.105.1 to 222.47.105.254222.47.105.255254
107222.47.106.0/24222.47.106.1 to 222.47.106.254222.47.106.255254
108222.47.107.0/24222.47.107.1 to 222.47.107.254222.47.107.255254
109222.47.108.0/24222.47.108.1 to 222.47.108.254222.47.108.255254
110222.47.109.0/24222.47.109.1 to 222.47.109.254222.47.109.255254
111222.47.110.0/24222.47.110.1 to 222.47.110.254222.47.110.255254
112222.47.111.0/24222.47.111.1 to 222.47.111.254222.47.111.255254
113222.47.112.0/24222.47.112.1 to 222.47.112.254222.47.112.255254
114222.47.113.0/24222.47.113.1 to 222.47.113.254222.47.113.255254
115222.47.114.0/24222.47.114.1 to 222.47.114.254222.47.114.255254
116222.47.115.0/24222.47.115.1 to 222.47.115.254222.47.115.255254
117222.47.116.0/24222.47.116.1 to 222.47.116.254222.47.116.255254
118222.47.117.0/24222.47.117.1 to 222.47.117.254222.47.117.255254
119222.47.118.0/24222.47.118.1 to 222.47.118.254222.47.118.255254
120222.47.119.0/24222.47.119.1 to 222.47.119.254222.47.119.255254
121222.47.120.0/24222.47.120.1 to 222.47.120.254222.47.120.255254
122222.47.121.0/24222.47.121.1 to 222.47.121.254222.47.121.255254
123222.47.122.0/24222.47.122.1 to 222.47.122.254222.47.122.255254
124222.47.123.0/24222.47.123.1 to 222.47.123.254222.47.123.255254
125222.47.124.0/24222.47.124.1 to 222.47.124.254222.47.124.255254
126222.47.125.0/24222.47.125.1 to 222.47.125.254222.47.125.255254
127222.47.126.0/24222.47.126.1 to 222.47.126.254222.47.126.255254
128222.47.127.0/24222.47.127.1 to 222.47.127.254222.47.127.255254

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.