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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.

Network241.3.64.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
241.3.64.0
Broadcast address
241.3.127.255
First usable
241.3.64.1
Last usable
241.3.127.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Reserved 240.0.0.0/4
Future use; not usable on most systems
Old class
E (reserved)
As numbers
Hex F1034000 · Integer 4043522048 to 4043538431
Reverse DNS zones
64.3.241.in-addr.arpa
65.3.241.in-addr.arpa
66.3.241.in-addr.arpa
67.3.241.in-addr.arpa
68.3.241.in-addr.arpa
69.3.241.in-addr.arpa
70.3.241.in-addr.arpa
71.3.241.in-addr.arpa
72.3.241.in-addr.arpa
73.3.241.in-addr.arpa
74.3.241.in-addr.arpa
75.3.241.in-addr.arpa
76.3.241.in-addr.arpa
77.3.241.in-addr.arpa
78.3.241.in-addr.arpa
79.3.241.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110001.00000011.01000000.00000000241.3.64.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network11110001.00000011.01000000.00000000241.3.64.0
Broadcast11110001.00000011.01111111.11111111241.3.127.255
Split into smaller subnets/25
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

241.3.64.0/18 makes 128 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1241.3.64.0/25241.3.64.1 to 241.3.64.126241.3.64.127126
2241.3.64.128/25241.3.64.129 to 241.3.64.254241.3.64.255126
3241.3.65.0/25241.3.65.1 to 241.3.65.126241.3.65.127126
4241.3.65.128/25241.3.65.129 to 241.3.65.254241.3.65.255126
5241.3.66.0/25241.3.66.1 to 241.3.66.126241.3.66.127126
6241.3.66.128/25241.3.66.129 to 241.3.66.254241.3.66.255126
7241.3.67.0/25241.3.67.1 to 241.3.67.126241.3.67.127126
8241.3.67.128/25241.3.67.129 to 241.3.67.254241.3.67.255126
9241.3.68.0/25241.3.68.1 to 241.3.68.126241.3.68.127126
10241.3.68.128/25241.3.68.129 to 241.3.68.254241.3.68.255126
11241.3.69.0/25241.3.69.1 to 241.3.69.126241.3.69.127126
12241.3.69.128/25241.3.69.129 to 241.3.69.254241.3.69.255126
13241.3.70.0/25241.3.70.1 to 241.3.70.126241.3.70.127126
14241.3.70.128/25241.3.70.129 to 241.3.70.254241.3.70.255126
15241.3.71.0/25241.3.71.1 to 241.3.71.126241.3.71.127126
16241.3.71.128/25241.3.71.129 to 241.3.71.254241.3.71.255126
17241.3.72.0/25241.3.72.1 to 241.3.72.126241.3.72.127126
18241.3.72.128/25241.3.72.129 to 241.3.72.254241.3.72.255126
19241.3.73.0/25241.3.73.1 to 241.3.73.126241.3.73.127126
20241.3.73.128/25241.3.73.129 to 241.3.73.254241.3.73.255126
21241.3.74.0/25241.3.74.1 to 241.3.74.126241.3.74.127126
22241.3.74.128/25241.3.74.129 to 241.3.74.254241.3.74.255126
23241.3.75.0/25241.3.75.1 to 241.3.75.126241.3.75.127126
24241.3.75.128/25241.3.75.129 to 241.3.75.254241.3.75.255126
25241.3.76.0/25241.3.76.1 to 241.3.76.126241.3.76.127126
26241.3.76.128/25241.3.76.129 to 241.3.76.254241.3.76.255126
27241.3.77.0/25241.3.77.1 to 241.3.77.126241.3.77.127126
28241.3.77.128/25241.3.77.129 to 241.3.77.254241.3.77.255126
29241.3.78.0/25241.3.78.1 to 241.3.78.126241.3.78.127126
30241.3.78.128/25241.3.78.129 to 241.3.78.254241.3.78.255126
31241.3.79.0/25241.3.79.1 to 241.3.79.126241.3.79.127126
32241.3.79.128/25241.3.79.129 to 241.3.79.254241.3.79.255126
33241.3.80.0/25241.3.80.1 to 241.3.80.126241.3.80.127126
34241.3.80.128/25241.3.80.129 to 241.3.80.254241.3.80.255126
35241.3.81.0/25241.3.81.1 to 241.3.81.126241.3.81.127126
36241.3.81.128/25241.3.81.129 to 241.3.81.254241.3.81.255126
37241.3.82.0/25241.3.82.1 to 241.3.82.126241.3.82.127126
38241.3.82.128/25241.3.82.129 to 241.3.82.254241.3.82.255126
39241.3.83.0/25241.3.83.1 to 241.3.83.126241.3.83.127126
40241.3.83.128/25241.3.83.129 to 241.3.83.254241.3.83.255126
41241.3.84.0/25241.3.84.1 to 241.3.84.126241.3.84.127126
42241.3.84.128/25241.3.84.129 to 241.3.84.254241.3.84.255126
43241.3.85.0/25241.3.85.1 to 241.3.85.126241.3.85.127126
44241.3.85.128/25241.3.85.129 to 241.3.85.254241.3.85.255126
45241.3.86.0/25241.3.86.1 to 241.3.86.126241.3.86.127126
46241.3.86.128/25241.3.86.129 to 241.3.86.254241.3.86.255126
47241.3.87.0/25241.3.87.1 to 241.3.87.126241.3.87.127126
48241.3.87.128/25241.3.87.129 to 241.3.87.254241.3.87.255126
49241.3.88.0/25241.3.88.1 to 241.3.88.126241.3.88.127126
50241.3.88.128/25241.3.88.129 to 241.3.88.254241.3.88.255126
51241.3.89.0/25241.3.89.1 to 241.3.89.126241.3.89.127126
52241.3.89.128/25241.3.89.129 to 241.3.89.254241.3.89.255126
53241.3.90.0/25241.3.90.1 to 241.3.90.126241.3.90.127126
54241.3.90.128/25241.3.90.129 to 241.3.90.254241.3.90.255126
55241.3.91.0/25241.3.91.1 to 241.3.91.126241.3.91.127126
56241.3.91.128/25241.3.91.129 to 241.3.91.254241.3.91.255126
57241.3.92.0/25241.3.92.1 to 241.3.92.126241.3.92.127126
58241.3.92.128/25241.3.92.129 to 241.3.92.254241.3.92.255126
59241.3.93.0/25241.3.93.1 to 241.3.93.126241.3.93.127126
60241.3.93.128/25241.3.93.129 to 241.3.93.254241.3.93.255126
61241.3.94.0/25241.3.94.1 to 241.3.94.126241.3.94.127126
62241.3.94.128/25241.3.94.129 to 241.3.94.254241.3.94.255126
63241.3.95.0/25241.3.95.1 to 241.3.95.126241.3.95.127126
64241.3.95.128/25241.3.95.129 to 241.3.95.254241.3.95.255126
65241.3.96.0/25241.3.96.1 to 241.3.96.126241.3.96.127126
66241.3.96.128/25241.3.96.129 to 241.3.96.254241.3.96.255126
67241.3.97.0/25241.3.97.1 to 241.3.97.126241.3.97.127126
68241.3.97.128/25241.3.97.129 to 241.3.97.254241.3.97.255126
69241.3.98.0/25241.3.98.1 to 241.3.98.126241.3.98.127126
70241.3.98.128/25241.3.98.129 to 241.3.98.254241.3.98.255126
71241.3.99.0/25241.3.99.1 to 241.3.99.126241.3.99.127126
72241.3.99.128/25241.3.99.129 to 241.3.99.254241.3.99.255126
73241.3.100.0/25241.3.100.1 to 241.3.100.126241.3.100.127126
74241.3.100.128/25241.3.100.129 to 241.3.100.254241.3.100.255126
75241.3.101.0/25241.3.101.1 to 241.3.101.126241.3.101.127126
76241.3.101.128/25241.3.101.129 to 241.3.101.254241.3.101.255126
77241.3.102.0/25241.3.102.1 to 241.3.102.126241.3.102.127126
78241.3.102.128/25241.3.102.129 to 241.3.102.254241.3.102.255126
79241.3.103.0/25241.3.103.1 to 241.3.103.126241.3.103.127126
80241.3.103.128/25241.3.103.129 to 241.3.103.254241.3.103.255126
81241.3.104.0/25241.3.104.1 to 241.3.104.126241.3.104.127126
82241.3.104.128/25241.3.104.129 to 241.3.104.254241.3.104.255126
83241.3.105.0/25241.3.105.1 to 241.3.105.126241.3.105.127126
84241.3.105.128/25241.3.105.129 to 241.3.105.254241.3.105.255126
85241.3.106.0/25241.3.106.1 to 241.3.106.126241.3.106.127126
86241.3.106.128/25241.3.106.129 to 241.3.106.254241.3.106.255126
87241.3.107.0/25241.3.107.1 to 241.3.107.126241.3.107.127126
88241.3.107.128/25241.3.107.129 to 241.3.107.254241.3.107.255126
89241.3.108.0/25241.3.108.1 to 241.3.108.126241.3.108.127126
90241.3.108.128/25241.3.108.129 to 241.3.108.254241.3.108.255126
91241.3.109.0/25241.3.109.1 to 241.3.109.126241.3.109.127126
92241.3.109.128/25241.3.109.129 to 241.3.109.254241.3.109.255126
93241.3.110.0/25241.3.110.1 to 241.3.110.126241.3.110.127126
94241.3.110.128/25241.3.110.129 to 241.3.110.254241.3.110.255126
95241.3.111.0/25241.3.111.1 to 241.3.111.126241.3.111.127126
96241.3.111.128/25241.3.111.129 to 241.3.111.254241.3.111.255126
97241.3.112.0/25241.3.112.1 to 241.3.112.126241.3.112.127126
98241.3.112.128/25241.3.112.129 to 241.3.112.254241.3.112.255126
99241.3.113.0/25241.3.113.1 to 241.3.113.126241.3.113.127126
100241.3.113.128/25241.3.113.129 to 241.3.113.254241.3.113.255126
101241.3.114.0/25241.3.114.1 to 241.3.114.126241.3.114.127126
102241.3.114.128/25241.3.114.129 to 241.3.114.254241.3.114.255126
103241.3.115.0/25241.3.115.1 to 241.3.115.126241.3.115.127126
104241.3.115.128/25241.3.115.129 to 241.3.115.254241.3.115.255126
105241.3.116.0/25241.3.116.1 to 241.3.116.126241.3.116.127126
106241.3.116.128/25241.3.116.129 to 241.3.116.254241.3.116.255126
107241.3.117.0/25241.3.117.1 to 241.3.117.126241.3.117.127126
108241.3.117.128/25241.3.117.129 to 241.3.117.254241.3.117.255126
109241.3.118.0/25241.3.118.1 to 241.3.118.126241.3.118.127126
110241.3.118.128/25241.3.118.129 to 241.3.118.254241.3.118.255126
111241.3.119.0/25241.3.119.1 to 241.3.119.126241.3.119.127126
112241.3.119.128/25241.3.119.129 to 241.3.119.254241.3.119.255126
113241.3.120.0/25241.3.120.1 to 241.3.120.126241.3.120.127126
114241.3.120.128/25241.3.120.129 to 241.3.120.254241.3.120.255126
115241.3.121.0/25241.3.121.1 to 241.3.121.126241.3.121.127126
116241.3.121.128/25241.3.121.129 to 241.3.121.254241.3.121.255126
117241.3.122.0/25241.3.122.1 to 241.3.122.126241.3.122.127126
118241.3.122.128/25241.3.122.129 to 241.3.122.254241.3.122.255126
119241.3.123.0/25241.3.123.1 to 241.3.123.126241.3.123.127126
120241.3.123.128/25241.3.123.129 to 241.3.123.254241.3.123.255126
121241.3.124.0/25241.3.124.1 to 241.3.124.126241.3.124.127126
122241.3.124.128/25241.3.124.129 to 241.3.124.254241.3.124.255126
123241.3.125.0/25241.3.125.1 to 241.3.125.126241.3.125.127126
124241.3.125.128/25241.3.125.129 to 241.3.125.254241.3.125.255126
125241.3.126.0/25241.3.126.1 to 241.3.126.126241.3.126.127126
126241.3.126.128/25241.3.126.129 to 241.3.126.254241.3.126.255126
127241.3.127.0/25241.3.127.1 to 241.3.127.126241.3.127.127126
128241.3.127.128/25241.3.127.129 to 241.3.127.254241.3.127.255126

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.