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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.

Network170.44.0.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
170.44.0.0
Broadcast address
170.44.63.255
First usable
170.44.0.1
Last usable
170.44.63.254
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
Public public
Old class
B (default /16)
As numbers
Hex AA2C0000 · Integer 2855010304 to 2855026687
Reverse DNS zones
0.44.170.in-addr.arpa
1.44.170.in-addr.arpa
2.44.170.in-addr.arpa
3.44.170.in-addr.arpa
4.44.170.in-addr.arpa
5.44.170.in-addr.arpa
6.44.170.in-addr.arpa
7.44.170.in-addr.arpa
8.44.170.in-addr.arpa
9.44.170.in-addr.arpa
10.44.170.in-addr.arpa
11.44.170.in-addr.arpa
12.44.170.in-addr.arpa
13.44.170.in-addr.arpa
14.44.170.in-addr.arpa
15.44.170.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
Address10101010.00101100.00000000.00000000170.44.0.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network10101010.00101100.00000000.00000000170.44.0.0
Broadcast10101010.00101100.00111111.11111111170.44.63.255
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)

170.44.0.0/18 makes 128 subnets of /25.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1170.44.0.0/25170.44.0.1 to 170.44.0.126170.44.0.127126
2170.44.0.128/25170.44.0.129 to 170.44.0.254170.44.0.255126
3170.44.1.0/25170.44.1.1 to 170.44.1.126170.44.1.127126
4170.44.1.128/25170.44.1.129 to 170.44.1.254170.44.1.255126
5170.44.2.0/25170.44.2.1 to 170.44.2.126170.44.2.127126
6170.44.2.128/25170.44.2.129 to 170.44.2.254170.44.2.255126
7170.44.3.0/25170.44.3.1 to 170.44.3.126170.44.3.127126
8170.44.3.128/25170.44.3.129 to 170.44.3.254170.44.3.255126
9170.44.4.0/25170.44.4.1 to 170.44.4.126170.44.4.127126
10170.44.4.128/25170.44.4.129 to 170.44.4.254170.44.4.255126
11170.44.5.0/25170.44.5.1 to 170.44.5.126170.44.5.127126
12170.44.5.128/25170.44.5.129 to 170.44.5.254170.44.5.255126
13170.44.6.0/25170.44.6.1 to 170.44.6.126170.44.6.127126
14170.44.6.128/25170.44.6.129 to 170.44.6.254170.44.6.255126
15170.44.7.0/25170.44.7.1 to 170.44.7.126170.44.7.127126
16170.44.7.128/25170.44.7.129 to 170.44.7.254170.44.7.255126
17170.44.8.0/25170.44.8.1 to 170.44.8.126170.44.8.127126
18170.44.8.128/25170.44.8.129 to 170.44.8.254170.44.8.255126
19170.44.9.0/25170.44.9.1 to 170.44.9.126170.44.9.127126
20170.44.9.128/25170.44.9.129 to 170.44.9.254170.44.9.255126
21170.44.10.0/25170.44.10.1 to 170.44.10.126170.44.10.127126
22170.44.10.128/25170.44.10.129 to 170.44.10.254170.44.10.255126
23170.44.11.0/25170.44.11.1 to 170.44.11.126170.44.11.127126
24170.44.11.128/25170.44.11.129 to 170.44.11.254170.44.11.255126
25170.44.12.0/25170.44.12.1 to 170.44.12.126170.44.12.127126
26170.44.12.128/25170.44.12.129 to 170.44.12.254170.44.12.255126
27170.44.13.0/25170.44.13.1 to 170.44.13.126170.44.13.127126
28170.44.13.128/25170.44.13.129 to 170.44.13.254170.44.13.255126
29170.44.14.0/25170.44.14.1 to 170.44.14.126170.44.14.127126
30170.44.14.128/25170.44.14.129 to 170.44.14.254170.44.14.255126
31170.44.15.0/25170.44.15.1 to 170.44.15.126170.44.15.127126
32170.44.15.128/25170.44.15.129 to 170.44.15.254170.44.15.255126
33170.44.16.0/25170.44.16.1 to 170.44.16.126170.44.16.127126
34170.44.16.128/25170.44.16.129 to 170.44.16.254170.44.16.255126
35170.44.17.0/25170.44.17.1 to 170.44.17.126170.44.17.127126
36170.44.17.128/25170.44.17.129 to 170.44.17.254170.44.17.255126
37170.44.18.0/25170.44.18.1 to 170.44.18.126170.44.18.127126
38170.44.18.128/25170.44.18.129 to 170.44.18.254170.44.18.255126
39170.44.19.0/25170.44.19.1 to 170.44.19.126170.44.19.127126
40170.44.19.128/25170.44.19.129 to 170.44.19.254170.44.19.255126
41170.44.20.0/25170.44.20.1 to 170.44.20.126170.44.20.127126
42170.44.20.128/25170.44.20.129 to 170.44.20.254170.44.20.255126
43170.44.21.0/25170.44.21.1 to 170.44.21.126170.44.21.127126
44170.44.21.128/25170.44.21.129 to 170.44.21.254170.44.21.255126
45170.44.22.0/25170.44.22.1 to 170.44.22.126170.44.22.127126
46170.44.22.128/25170.44.22.129 to 170.44.22.254170.44.22.255126
47170.44.23.0/25170.44.23.1 to 170.44.23.126170.44.23.127126
48170.44.23.128/25170.44.23.129 to 170.44.23.254170.44.23.255126
49170.44.24.0/25170.44.24.1 to 170.44.24.126170.44.24.127126
50170.44.24.128/25170.44.24.129 to 170.44.24.254170.44.24.255126
51170.44.25.0/25170.44.25.1 to 170.44.25.126170.44.25.127126
52170.44.25.128/25170.44.25.129 to 170.44.25.254170.44.25.255126
53170.44.26.0/25170.44.26.1 to 170.44.26.126170.44.26.127126
54170.44.26.128/25170.44.26.129 to 170.44.26.254170.44.26.255126
55170.44.27.0/25170.44.27.1 to 170.44.27.126170.44.27.127126
56170.44.27.128/25170.44.27.129 to 170.44.27.254170.44.27.255126
57170.44.28.0/25170.44.28.1 to 170.44.28.126170.44.28.127126
58170.44.28.128/25170.44.28.129 to 170.44.28.254170.44.28.255126
59170.44.29.0/25170.44.29.1 to 170.44.29.126170.44.29.127126
60170.44.29.128/25170.44.29.129 to 170.44.29.254170.44.29.255126
61170.44.30.0/25170.44.30.1 to 170.44.30.126170.44.30.127126
62170.44.30.128/25170.44.30.129 to 170.44.30.254170.44.30.255126
63170.44.31.0/25170.44.31.1 to 170.44.31.126170.44.31.127126
64170.44.31.128/25170.44.31.129 to 170.44.31.254170.44.31.255126
65170.44.32.0/25170.44.32.1 to 170.44.32.126170.44.32.127126
66170.44.32.128/25170.44.32.129 to 170.44.32.254170.44.32.255126
67170.44.33.0/25170.44.33.1 to 170.44.33.126170.44.33.127126
68170.44.33.128/25170.44.33.129 to 170.44.33.254170.44.33.255126
69170.44.34.0/25170.44.34.1 to 170.44.34.126170.44.34.127126
70170.44.34.128/25170.44.34.129 to 170.44.34.254170.44.34.255126
71170.44.35.0/25170.44.35.1 to 170.44.35.126170.44.35.127126
72170.44.35.128/25170.44.35.129 to 170.44.35.254170.44.35.255126
73170.44.36.0/25170.44.36.1 to 170.44.36.126170.44.36.127126
74170.44.36.128/25170.44.36.129 to 170.44.36.254170.44.36.255126
75170.44.37.0/25170.44.37.1 to 170.44.37.126170.44.37.127126
76170.44.37.128/25170.44.37.129 to 170.44.37.254170.44.37.255126
77170.44.38.0/25170.44.38.1 to 170.44.38.126170.44.38.127126
78170.44.38.128/25170.44.38.129 to 170.44.38.254170.44.38.255126
79170.44.39.0/25170.44.39.1 to 170.44.39.126170.44.39.127126
80170.44.39.128/25170.44.39.129 to 170.44.39.254170.44.39.255126
81170.44.40.0/25170.44.40.1 to 170.44.40.126170.44.40.127126
82170.44.40.128/25170.44.40.129 to 170.44.40.254170.44.40.255126
83170.44.41.0/25170.44.41.1 to 170.44.41.126170.44.41.127126
84170.44.41.128/25170.44.41.129 to 170.44.41.254170.44.41.255126
85170.44.42.0/25170.44.42.1 to 170.44.42.126170.44.42.127126
86170.44.42.128/25170.44.42.129 to 170.44.42.254170.44.42.255126
87170.44.43.0/25170.44.43.1 to 170.44.43.126170.44.43.127126
88170.44.43.128/25170.44.43.129 to 170.44.43.254170.44.43.255126
89170.44.44.0/25170.44.44.1 to 170.44.44.126170.44.44.127126
90170.44.44.128/25170.44.44.129 to 170.44.44.254170.44.44.255126
91170.44.45.0/25170.44.45.1 to 170.44.45.126170.44.45.127126
92170.44.45.128/25170.44.45.129 to 170.44.45.254170.44.45.255126
93170.44.46.0/25170.44.46.1 to 170.44.46.126170.44.46.127126
94170.44.46.128/25170.44.46.129 to 170.44.46.254170.44.46.255126
95170.44.47.0/25170.44.47.1 to 170.44.47.126170.44.47.127126
96170.44.47.128/25170.44.47.129 to 170.44.47.254170.44.47.255126
97170.44.48.0/25170.44.48.1 to 170.44.48.126170.44.48.127126
98170.44.48.128/25170.44.48.129 to 170.44.48.254170.44.48.255126
99170.44.49.0/25170.44.49.1 to 170.44.49.126170.44.49.127126
100170.44.49.128/25170.44.49.129 to 170.44.49.254170.44.49.255126
101170.44.50.0/25170.44.50.1 to 170.44.50.126170.44.50.127126
102170.44.50.128/25170.44.50.129 to 170.44.50.254170.44.50.255126
103170.44.51.0/25170.44.51.1 to 170.44.51.126170.44.51.127126
104170.44.51.128/25170.44.51.129 to 170.44.51.254170.44.51.255126
105170.44.52.0/25170.44.52.1 to 170.44.52.126170.44.52.127126
106170.44.52.128/25170.44.52.129 to 170.44.52.254170.44.52.255126
107170.44.53.0/25170.44.53.1 to 170.44.53.126170.44.53.127126
108170.44.53.128/25170.44.53.129 to 170.44.53.254170.44.53.255126
109170.44.54.0/25170.44.54.1 to 170.44.54.126170.44.54.127126
110170.44.54.128/25170.44.54.129 to 170.44.54.254170.44.54.255126
111170.44.55.0/25170.44.55.1 to 170.44.55.126170.44.55.127126
112170.44.55.128/25170.44.55.129 to 170.44.55.254170.44.55.255126
113170.44.56.0/25170.44.56.1 to 170.44.56.126170.44.56.127126
114170.44.56.128/25170.44.56.129 to 170.44.56.254170.44.56.255126
115170.44.57.0/25170.44.57.1 to 170.44.57.126170.44.57.127126
116170.44.57.128/25170.44.57.129 to 170.44.57.254170.44.57.255126
117170.44.58.0/25170.44.58.1 to 170.44.58.126170.44.58.127126
118170.44.58.128/25170.44.58.129 to 170.44.58.254170.44.58.255126
119170.44.59.0/25170.44.59.1 to 170.44.59.126170.44.59.127126
120170.44.59.128/25170.44.59.129 to 170.44.59.254170.44.59.255126
121170.44.60.0/25170.44.60.1 to 170.44.60.126170.44.60.127126
122170.44.60.128/25170.44.60.129 to 170.44.60.254170.44.60.255126
123170.44.61.0/25170.44.61.1 to 170.44.61.126170.44.61.127126
124170.44.61.128/25170.44.61.129 to 170.44.61.254170.44.61.255126
125170.44.62.0/25170.44.62.1 to 170.44.62.126170.44.62.127126
126170.44.62.128/25170.44.62.129 to 170.44.62.254170.44.62.255126
127170.44.63.0/25170.44.63.1 to 170.44.63.126170.44.63.127126
128170.44.63.128/25170.44.63.129 to 170.44.63.254170.44.63.255126

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.