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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.

Network241.3.64.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
241.3.64.0
Broadcast address
241.3.95.255
First usable
241.3.64.1
Last usable
241.3.95.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
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 4043530239
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 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11110001.00000011.01000000.00000000241.3.64.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network11110001.00000011.01000000.00000000241.3.64.0
Broadcast11110001.00000011.01011111.11111111241.3.95.255
Split into smaller subnets/26
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

241.3.64.0/19 makes 128 subnets of /26.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1241.3.64.0/26241.3.64.1 to 241.3.64.62241.3.64.6362
2241.3.64.64/26241.3.64.65 to 241.3.64.126241.3.64.12762
3241.3.64.128/26241.3.64.129 to 241.3.64.190241.3.64.19162
4241.3.64.192/26241.3.64.193 to 241.3.64.254241.3.64.25562
5241.3.65.0/26241.3.65.1 to 241.3.65.62241.3.65.6362
6241.3.65.64/26241.3.65.65 to 241.3.65.126241.3.65.12762
7241.3.65.128/26241.3.65.129 to 241.3.65.190241.3.65.19162
8241.3.65.192/26241.3.65.193 to 241.3.65.254241.3.65.25562
9241.3.66.0/26241.3.66.1 to 241.3.66.62241.3.66.6362
10241.3.66.64/26241.3.66.65 to 241.3.66.126241.3.66.12762
11241.3.66.128/26241.3.66.129 to 241.3.66.190241.3.66.19162
12241.3.66.192/26241.3.66.193 to 241.3.66.254241.3.66.25562
13241.3.67.0/26241.3.67.1 to 241.3.67.62241.3.67.6362
14241.3.67.64/26241.3.67.65 to 241.3.67.126241.3.67.12762
15241.3.67.128/26241.3.67.129 to 241.3.67.190241.3.67.19162
16241.3.67.192/26241.3.67.193 to 241.3.67.254241.3.67.25562
17241.3.68.0/26241.3.68.1 to 241.3.68.62241.3.68.6362
18241.3.68.64/26241.3.68.65 to 241.3.68.126241.3.68.12762
19241.3.68.128/26241.3.68.129 to 241.3.68.190241.3.68.19162
20241.3.68.192/26241.3.68.193 to 241.3.68.254241.3.68.25562
21241.3.69.0/26241.3.69.1 to 241.3.69.62241.3.69.6362
22241.3.69.64/26241.3.69.65 to 241.3.69.126241.3.69.12762
23241.3.69.128/26241.3.69.129 to 241.3.69.190241.3.69.19162
24241.3.69.192/26241.3.69.193 to 241.3.69.254241.3.69.25562
25241.3.70.0/26241.3.70.1 to 241.3.70.62241.3.70.6362
26241.3.70.64/26241.3.70.65 to 241.3.70.126241.3.70.12762
27241.3.70.128/26241.3.70.129 to 241.3.70.190241.3.70.19162
28241.3.70.192/26241.3.70.193 to 241.3.70.254241.3.70.25562
29241.3.71.0/26241.3.71.1 to 241.3.71.62241.3.71.6362
30241.3.71.64/26241.3.71.65 to 241.3.71.126241.3.71.12762
31241.3.71.128/26241.3.71.129 to 241.3.71.190241.3.71.19162
32241.3.71.192/26241.3.71.193 to 241.3.71.254241.3.71.25562
33241.3.72.0/26241.3.72.1 to 241.3.72.62241.3.72.6362
34241.3.72.64/26241.3.72.65 to 241.3.72.126241.3.72.12762
35241.3.72.128/26241.3.72.129 to 241.3.72.190241.3.72.19162
36241.3.72.192/26241.3.72.193 to 241.3.72.254241.3.72.25562
37241.3.73.0/26241.3.73.1 to 241.3.73.62241.3.73.6362
38241.3.73.64/26241.3.73.65 to 241.3.73.126241.3.73.12762
39241.3.73.128/26241.3.73.129 to 241.3.73.190241.3.73.19162
40241.3.73.192/26241.3.73.193 to 241.3.73.254241.3.73.25562
41241.3.74.0/26241.3.74.1 to 241.3.74.62241.3.74.6362
42241.3.74.64/26241.3.74.65 to 241.3.74.126241.3.74.12762
43241.3.74.128/26241.3.74.129 to 241.3.74.190241.3.74.19162
44241.3.74.192/26241.3.74.193 to 241.3.74.254241.3.74.25562
45241.3.75.0/26241.3.75.1 to 241.3.75.62241.3.75.6362
46241.3.75.64/26241.3.75.65 to 241.3.75.126241.3.75.12762
47241.3.75.128/26241.3.75.129 to 241.3.75.190241.3.75.19162
48241.3.75.192/26241.3.75.193 to 241.3.75.254241.3.75.25562
49241.3.76.0/26241.3.76.1 to 241.3.76.62241.3.76.6362
50241.3.76.64/26241.3.76.65 to 241.3.76.126241.3.76.12762
51241.3.76.128/26241.3.76.129 to 241.3.76.190241.3.76.19162
52241.3.76.192/26241.3.76.193 to 241.3.76.254241.3.76.25562
53241.3.77.0/26241.3.77.1 to 241.3.77.62241.3.77.6362
54241.3.77.64/26241.3.77.65 to 241.3.77.126241.3.77.12762
55241.3.77.128/26241.3.77.129 to 241.3.77.190241.3.77.19162
56241.3.77.192/26241.3.77.193 to 241.3.77.254241.3.77.25562
57241.3.78.0/26241.3.78.1 to 241.3.78.62241.3.78.6362
58241.3.78.64/26241.3.78.65 to 241.3.78.126241.3.78.12762
59241.3.78.128/26241.3.78.129 to 241.3.78.190241.3.78.19162
60241.3.78.192/26241.3.78.193 to 241.3.78.254241.3.78.25562
61241.3.79.0/26241.3.79.1 to 241.3.79.62241.3.79.6362
62241.3.79.64/26241.3.79.65 to 241.3.79.126241.3.79.12762
63241.3.79.128/26241.3.79.129 to 241.3.79.190241.3.79.19162
64241.3.79.192/26241.3.79.193 to 241.3.79.254241.3.79.25562
65241.3.80.0/26241.3.80.1 to 241.3.80.62241.3.80.6362
66241.3.80.64/26241.3.80.65 to 241.3.80.126241.3.80.12762
67241.3.80.128/26241.3.80.129 to 241.3.80.190241.3.80.19162
68241.3.80.192/26241.3.80.193 to 241.3.80.254241.3.80.25562
69241.3.81.0/26241.3.81.1 to 241.3.81.62241.3.81.6362
70241.3.81.64/26241.3.81.65 to 241.3.81.126241.3.81.12762
71241.3.81.128/26241.3.81.129 to 241.3.81.190241.3.81.19162
72241.3.81.192/26241.3.81.193 to 241.3.81.254241.3.81.25562
73241.3.82.0/26241.3.82.1 to 241.3.82.62241.3.82.6362
74241.3.82.64/26241.3.82.65 to 241.3.82.126241.3.82.12762
75241.3.82.128/26241.3.82.129 to 241.3.82.190241.3.82.19162
76241.3.82.192/26241.3.82.193 to 241.3.82.254241.3.82.25562
77241.3.83.0/26241.3.83.1 to 241.3.83.62241.3.83.6362
78241.3.83.64/26241.3.83.65 to 241.3.83.126241.3.83.12762
79241.3.83.128/26241.3.83.129 to 241.3.83.190241.3.83.19162
80241.3.83.192/26241.3.83.193 to 241.3.83.254241.3.83.25562
81241.3.84.0/26241.3.84.1 to 241.3.84.62241.3.84.6362
82241.3.84.64/26241.3.84.65 to 241.3.84.126241.3.84.12762
83241.3.84.128/26241.3.84.129 to 241.3.84.190241.3.84.19162
84241.3.84.192/26241.3.84.193 to 241.3.84.254241.3.84.25562
85241.3.85.0/26241.3.85.1 to 241.3.85.62241.3.85.6362
86241.3.85.64/26241.3.85.65 to 241.3.85.126241.3.85.12762
87241.3.85.128/26241.3.85.129 to 241.3.85.190241.3.85.19162
88241.3.85.192/26241.3.85.193 to 241.3.85.254241.3.85.25562
89241.3.86.0/26241.3.86.1 to 241.3.86.62241.3.86.6362
90241.3.86.64/26241.3.86.65 to 241.3.86.126241.3.86.12762
91241.3.86.128/26241.3.86.129 to 241.3.86.190241.3.86.19162
92241.3.86.192/26241.3.86.193 to 241.3.86.254241.3.86.25562
93241.3.87.0/26241.3.87.1 to 241.3.87.62241.3.87.6362
94241.3.87.64/26241.3.87.65 to 241.3.87.126241.3.87.12762
95241.3.87.128/26241.3.87.129 to 241.3.87.190241.3.87.19162
96241.3.87.192/26241.3.87.193 to 241.3.87.254241.3.87.25562
97241.3.88.0/26241.3.88.1 to 241.3.88.62241.3.88.6362
98241.3.88.64/26241.3.88.65 to 241.3.88.126241.3.88.12762
99241.3.88.128/26241.3.88.129 to 241.3.88.190241.3.88.19162
100241.3.88.192/26241.3.88.193 to 241.3.88.254241.3.88.25562
101241.3.89.0/26241.3.89.1 to 241.3.89.62241.3.89.6362
102241.3.89.64/26241.3.89.65 to 241.3.89.126241.3.89.12762
103241.3.89.128/26241.3.89.129 to 241.3.89.190241.3.89.19162
104241.3.89.192/26241.3.89.193 to 241.3.89.254241.3.89.25562
105241.3.90.0/26241.3.90.1 to 241.3.90.62241.3.90.6362
106241.3.90.64/26241.3.90.65 to 241.3.90.126241.3.90.12762
107241.3.90.128/26241.3.90.129 to 241.3.90.190241.3.90.19162
108241.3.90.192/26241.3.90.193 to 241.3.90.254241.3.90.25562
109241.3.91.0/26241.3.91.1 to 241.3.91.62241.3.91.6362
110241.3.91.64/26241.3.91.65 to 241.3.91.126241.3.91.12762
111241.3.91.128/26241.3.91.129 to 241.3.91.190241.3.91.19162
112241.3.91.192/26241.3.91.193 to 241.3.91.254241.3.91.25562
113241.3.92.0/26241.3.92.1 to 241.3.92.62241.3.92.6362
114241.3.92.64/26241.3.92.65 to 241.3.92.126241.3.92.12762
115241.3.92.128/26241.3.92.129 to 241.3.92.190241.3.92.19162
116241.3.92.192/26241.3.92.193 to 241.3.92.254241.3.92.25562
117241.3.93.0/26241.3.93.1 to 241.3.93.62241.3.93.6362
118241.3.93.64/26241.3.93.65 to 241.3.93.126241.3.93.12762
119241.3.93.128/26241.3.93.129 to 241.3.93.190241.3.93.19162
120241.3.93.192/26241.3.93.193 to 241.3.93.254241.3.93.25562
121241.3.94.0/26241.3.94.1 to 241.3.94.62241.3.94.6362
122241.3.94.64/26241.3.94.65 to 241.3.94.126241.3.94.12762
123241.3.94.128/26241.3.94.129 to 241.3.94.190241.3.94.19162
124241.3.94.192/26241.3.94.193 to 241.3.94.254241.3.94.25562
125241.3.95.0/26241.3.95.1 to 241.3.95.62241.3.95.6362
126241.3.95.64/26241.3.95.65 to 241.3.95.126241.3.95.12762
127241.3.95.128/26241.3.95.129 to 241.3.95.190241.3.95.19162
128241.3.95.192/26241.3.95.193 to 241.3.95.254241.3.95.25562

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.