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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.

Network211.92.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
211.92.0.0
Broadcast address
211.92.127.255
First usable
211.92.0.1
Last usable
211.92.127.254
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 D35C0000 · Integer 3546021888 to 3546054655
Reverse DNS zones
0.92.211.in-addr.arpa
1.92.211.in-addr.arpa
2.92.211.in-addr.arpa
3.92.211.in-addr.arpa
4.92.211.in-addr.arpa
5.92.211.in-addr.arpa
6.92.211.in-addr.arpa
7.92.211.in-addr.arpa
8.92.211.in-addr.arpa
9.92.211.in-addr.arpa
10.92.211.in-addr.arpa
11.92.211.in-addr.arpa
12.92.211.in-addr.arpa
13.92.211.in-addr.arpa
14.92.211.in-addr.arpa
15.92.211.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
Address11010011.01011100.00000000.00000000211.92.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network11010011.01011100.00000000.00000000211.92.0.0
Broadcast11010011.01011100.01111111.11111111211.92.127.255
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)

211.92.0.0/17 makes 128 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1211.92.0.0/24211.92.0.1 to 211.92.0.254211.92.0.255254
2211.92.1.0/24211.92.1.1 to 211.92.1.254211.92.1.255254
3211.92.2.0/24211.92.2.1 to 211.92.2.254211.92.2.255254
4211.92.3.0/24211.92.3.1 to 211.92.3.254211.92.3.255254
5211.92.4.0/24211.92.4.1 to 211.92.4.254211.92.4.255254
6211.92.5.0/24211.92.5.1 to 211.92.5.254211.92.5.255254
7211.92.6.0/24211.92.6.1 to 211.92.6.254211.92.6.255254
8211.92.7.0/24211.92.7.1 to 211.92.7.254211.92.7.255254
9211.92.8.0/24211.92.8.1 to 211.92.8.254211.92.8.255254
10211.92.9.0/24211.92.9.1 to 211.92.9.254211.92.9.255254
11211.92.10.0/24211.92.10.1 to 211.92.10.254211.92.10.255254
12211.92.11.0/24211.92.11.1 to 211.92.11.254211.92.11.255254
13211.92.12.0/24211.92.12.1 to 211.92.12.254211.92.12.255254
14211.92.13.0/24211.92.13.1 to 211.92.13.254211.92.13.255254
15211.92.14.0/24211.92.14.1 to 211.92.14.254211.92.14.255254
16211.92.15.0/24211.92.15.1 to 211.92.15.254211.92.15.255254
17211.92.16.0/24211.92.16.1 to 211.92.16.254211.92.16.255254
18211.92.17.0/24211.92.17.1 to 211.92.17.254211.92.17.255254
19211.92.18.0/24211.92.18.1 to 211.92.18.254211.92.18.255254
20211.92.19.0/24211.92.19.1 to 211.92.19.254211.92.19.255254
21211.92.20.0/24211.92.20.1 to 211.92.20.254211.92.20.255254
22211.92.21.0/24211.92.21.1 to 211.92.21.254211.92.21.255254
23211.92.22.0/24211.92.22.1 to 211.92.22.254211.92.22.255254
24211.92.23.0/24211.92.23.1 to 211.92.23.254211.92.23.255254
25211.92.24.0/24211.92.24.1 to 211.92.24.254211.92.24.255254
26211.92.25.0/24211.92.25.1 to 211.92.25.254211.92.25.255254
27211.92.26.0/24211.92.26.1 to 211.92.26.254211.92.26.255254
28211.92.27.0/24211.92.27.1 to 211.92.27.254211.92.27.255254
29211.92.28.0/24211.92.28.1 to 211.92.28.254211.92.28.255254
30211.92.29.0/24211.92.29.1 to 211.92.29.254211.92.29.255254
31211.92.30.0/24211.92.30.1 to 211.92.30.254211.92.30.255254
32211.92.31.0/24211.92.31.1 to 211.92.31.254211.92.31.255254
33211.92.32.0/24211.92.32.1 to 211.92.32.254211.92.32.255254
34211.92.33.0/24211.92.33.1 to 211.92.33.254211.92.33.255254
35211.92.34.0/24211.92.34.1 to 211.92.34.254211.92.34.255254
36211.92.35.0/24211.92.35.1 to 211.92.35.254211.92.35.255254
37211.92.36.0/24211.92.36.1 to 211.92.36.254211.92.36.255254
38211.92.37.0/24211.92.37.1 to 211.92.37.254211.92.37.255254
39211.92.38.0/24211.92.38.1 to 211.92.38.254211.92.38.255254
40211.92.39.0/24211.92.39.1 to 211.92.39.254211.92.39.255254
41211.92.40.0/24211.92.40.1 to 211.92.40.254211.92.40.255254
42211.92.41.0/24211.92.41.1 to 211.92.41.254211.92.41.255254
43211.92.42.0/24211.92.42.1 to 211.92.42.254211.92.42.255254
44211.92.43.0/24211.92.43.1 to 211.92.43.254211.92.43.255254
45211.92.44.0/24211.92.44.1 to 211.92.44.254211.92.44.255254
46211.92.45.0/24211.92.45.1 to 211.92.45.254211.92.45.255254
47211.92.46.0/24211.92.46.1 to 211.92.46.254211.92.46.255254
48211.92.47.0/24211.92.47.1 to 211.92.47.254211.92.47.255254
49211.92.48.0/24211.92.48.1 to 211.92.48.254211.92.48.255254
50211.92.49.0/24211.92.49.1 to 211.92.49.254211.92.49.255254
51211.92.50.0/24211.92.50.1 to 211.92.50.254211.92.50.255254
52211.92.51.0/24211.92.51.1 to 211.92.51.254211.92.51.255254
53211.92.52.0/24211.92.52.1 to 211.92.52.254211.92.52.255254
54211.92.53.0/24211.92.53.1 to 211.92.53.254211.92.53.255254
55211.92.54.0/24211.92.54.1 to 211.92.54.254211.92.54.255254
56211.92.55.0/24211.92.55.1 to 211.92.55.254211.92.55.255254
57211.92.56.0/24211.92.56.1 to 211.92.56.254211.92.56.255254
58211.92.57.0/24211.92.57.1 to 211.92.57.254211.92.57.255254
59211.92.58.0/24211.92.58.1 to 211.92.58.254211.92.58.255254
60211.92.59.0/24211.92.59.1 to 211.92.59.254211.92.59.255254
61211.92.60.0/24211.92.60.1 to 211.92.60.254211.92.60.255254
62211.92.61.0/24211.92.61.1 to 211.92.61.254211.92.61.255254
63211.92.62.0/24211.92.62.1 to 211.92.62.254211.92.62.255254
64211.92.63.0/24211.92.63.1 to 211.92.63.254211.92.63.255254
65211.92.64.0/24211.92.64.1 to 211.92.64.254211.92.64.255254
66211.92.65.0/24211.92.65.1 to 211.92.65.254211.92.65.255254
67211.92.66.0/24211.92.66.1 to 211.92.66.254211.92.66.255254
68211.92.67.0/24211.92.67.1 to 211.92.67.254211.92.67.255254
69211.92.68.0/24211.92.68.1 to 211.92.68.254211.92.68.255254
70211.92.69.0/24211.92.69.1 to 211.92.69.254211.92.69.255254
71211.92.70.0/24211.92.70.1 to 211.92.70.254211.92.70.255254
72211.92.71.0/24211.92.71.1 to 211.92.71.254211.92.71.255254
73211.92.72.0/24211.92.72.1 to 211.92.72.254211.92.72.255254
74211.92.73.0/24211.92.73.1 to 211.92.73.254211.92.73.255254
75211.92.74.0/24211.92.74.1 to 211.92.74.254211.92.74.255254
76211.92.75.0/24211.92.75.1 to 211.92.75.254211.92.75.255254
77211.92.76.0/24211.92.76.1 to 211.92.76.254211.92.76.255254
78211.92.77.0/24211.92.77.1 to 211.92.77.254211.92.77.255254
79211.92.78.0/24211.92.78.1 to 211.92.78.254211.92.78.255254
80211.92.79.0/24211.92.79.1 to 211.92.79.254211.92.79.255254
81211.92.80.0/24211.92.80.1 to 211.92.80.254211.92.80.255254
82211.92.81.0/24211.92.81.1 to 211.92.81.254211.92.81.255254
83211.92.82.0/24211.92.82.1 to 211.92.82.254211.92.82.255254
84211.92.83.0/24211.92.83.1 to 211.92.83.254211.92.83.255254
85211.92.84.0/24211.92.84.1 to 211.92.84.254211.92.84.255254
86211.92.85.0/24211.92.85.1 to 211.92.85.254211.92.85.255254
87211.92.86.0/24211.92.86.1 to 211.92.86.254211.92.86.255254
88211.92.87.0/24211.92.87.1 to 211.92.87.254211.92.87.255254
89211.92.88.0/24211.92.88.1 to 211.92.88.254211.92.88.255254
90211.92.89.0/24211.92.89.1 to 211.92.89.254211.92.89.255254
91211.92.90.0/24211.92.90.1 to 211.92.90.254211.92.90.255254
92211.92.91.0/24211.92.91.1 to 211.92.91.254211.92.91.255254
93211.92.92.0/24211.92.92.1 to 211.92.92.254211.92.92.255254
94211.92.93.0/24211.92.93.1 to 211.92.93.254211.92.93.255254
95211.92.94.0/24211.92.94.1 to 211.92.94.254211.92.94.255254
96211.92.95.0/24211.92.95.1 to 211.92.95.254211.92.95.255254
97211.92.96.0/24211.92.96.1 to 211.92.96.254211.92.96.255254
98211.92.97.0/24211.92.97.1 to 211.92.97.254211.92.97.255254
99211.92.98.0/24211.92.98.1 to 211.92.98.254211.92.98.255254
100211.92.99.0/24211.92.99.1 to 211.92.99.254211.92.99.255254
101211.92.100.0/24211.92.100.1 to 211.92.100.254211.92.100.255254
102211.92.101.0/24211.92.101.1 to 211.92.101.254211.92.101.255254
103211.92.102.0/24211.92.102.1 to 211.92.102.254211.92.102.255254
104211.92.103.0/24211.92.103.1 to 211.92.103.254211.92.103.255254
105211.92.104.0/24211.92.104.1 to 211.92.104.254211.92.104.255254
106211.92.105.0/24211.92.105.1 to 211.92.105.254211.92.105.255254
107211.92.106.0/24211.92.106.1 to 211.92.106.254211.92.106.255254
108211.92.107.0/24211.92.107.1 to 211.92.107.254211.92.107.255254
109211.92.108.0/24211.92.108.1 to 211.92.108.254211.92.108.255254
110211.92.109.0/24211.92.109.1 to 211.92.109.254211.92.109.255254
111211.92.110.0/24211.92.110.1 to 211.92.110.254211.92.110.255254
112211.92.111.0/24211.92.111.1 to 211.92.111.254211.92.111.255254
113211.92.112.0/24211.92.112.1 to 211.92.112.254211.92.112.255254
114211.92.113.0/24211.92.113.1 to 211.92.113.254211.92.113.255254
115211.92.114.0/24211.92.114.1 to 211.92.114.254211.92.114.255254
116211.92.115.0/24211.92.115.1 to 211.92.115.254211.92.115.255254
117211.92.116.0/24211.92.116.1 to 211.92.116.254211.92.116.255254
118211.92.117.0/24211.92.117.1 to 211.92.117.254211.92.117.255254
119211.92.118.0/24211.92.118.1 to 211.92.118.254211.92.118.255254
120211.92.119.0/24211.92.119.1 to 211.92.119.254211.92.119.255254
121211.92.120.0/24211.92.120.1 to 211.92.120.254211.92.120.255254
122211.92.121.0/24211.92.121.1 to 211.92.121.254211.92.121.255254
123211.92.122.0/24211.92.122.1 to 211.92.122.254211.92.122.255254
124211.92.123.0/24211.92.123.1 to 211.92.123.254211.92.123.255254
125211.92.124.0/24211.92.124.1 to 211.92.124.254211.92.124.255254
126211.92.125.0/24211.92.125.1 to 211.92.125.254211.92.125.255254
127211.92.126.0/24211.92.126.1 to 211.92.126.254211.92.126.255254
128211.92.127.0/24211.92.127.1 to 211.92.127.254211.92.127.255254

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.