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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.

Network204.35.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
204.35.0.0
Broadcast address
204.35.127.255
First usable
204.35.0.1
Last usable
204.35.127.254
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 CC230000 · Integer 3424845824 to 3424878591
Reverse DNS zones
0.35.204.in-addr.arpa
1.35.204.in-addr.arpa
2.35.204.in-addr.arpa
3.35.204.in-addr.arpa
4.35.204.in-addr.arpa
5.35.204.in-addr.arpa
6.35.204.in-addr.arpa
7.35.204.in-addr.arpa
8.35.204.in-addr.arpa
9.35.204.in-addr.arpa
10.35.204.in-addr.arpa
11.35.204.in-addr.arpa
12.35.204.in-addr.arpa
13.35.204.in-addr.arpa
14.35.204.in-addr.arpa
15.35.204.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
Address11001100.00100011.00000000.00000000204.35.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network11001100.00100011.00000000.00000000204.35.0.0
Broadcast11001100.00100011.01111111.11111111204.35.127.255
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)

204.35.0.0/17 makes 128 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1204.35.0.0/24204.35.0.1 to 204.35.0.254204.35.0.255254
2204.35.1.0/24204.35.1.1 to 204.35.1.254204.35.1.255254
3204.35.2.0/24204.35.2.1 to 204.35.2.254204.35.2.255254
4204.35.3.0/24204.35.3.1 to 204.35.3.254204.35.3.255254
5204.35.4.0/24204.35.4.1 to 204.35.4.254204.35.4.255254
6204.35.5.0/24204.35.5.1 to 204.35.5.254204.35.5.255254
7204.35.6.0/24204.35.6.1 to 204.35.6.254204.35.6.255254
8204.35.7.0/24204.35.7.1 to 204.35.7.254204.35.7.255254
9204.35.8.0/24204.35.8.1 to 204.35.8.254204.35.8.255254
10204.35.9.0/24204.35.9.1 to 204.35.9.254204.35.9.255254
11204.35.10.0/24204.35.10.1 to 204.35.10.254204.35.10.255254
12204.35.11.0/24204.35.11.1 to 204.35.11.254204.35.11.255254
13204.35.12.0/24204.35.12.1 to 204.35.12.254204.35.12.255254
14204.35.13.0/24204.35.13.1 to 204.35.13.254204.35.13.255254
15204.35.14.0/24204.35.14.1 to 204.35.14.254204.35.14.255254
16204.35.15.0/24204.35.15.1 to 204.35.15.254204.35.15.255254
17204.35.16.0/24204.35.16.1 to 204.35.16.254204.35.16.255254
18204.35.17.0/24204.35.17.1 to 204.35.17.254204.35.17.255254
19204.35.18.0/24204.35.18.1 to 204.35.18.254204.35.18.255254
20204.35.19.0/24204.35.19.1 to 204.35.19.254204.35.19.255254
21204.35.20.0/24204.35.20.1 to 204.35.20.254204.35.20.255254
22204.35.21.0/24204.35.21.1 to 204.35.21.254204.35.21.255254
23204.35.22.0/24204.35.22.1 to 204.35.22.254204.35.22.255254
24204.35.23.0/24204.35.23.1 to 204.35.23.254204.35.23.255254
25204.35.24.0/24204.35.24.1 to 204.35.24.254204.35.24.255254
26204.35.25.0/24204.35.25.1 to 204.35.25.254204.35.25.255254
27204.35.26.0/24204.35.26.1 to 204.35.26.254204.35.26.255254
28204.35.27.0/24204.35.27.1 to 204.35.27.254204.35.27.255254
29204.35.28.0/24204.35.28.1 to 204.35.28.254204.35.28.255254
30204.35.29.0/24204.35.29.1 to 204.35.29.254204.35.29.255254
31204.35.30.0/24204.35.30.1 to 204.35.30.254204.35.30.255254
32204.35.31.0/24204.35.31.1 to 204.35.31.254204.35.31.255254
33204.35.32.0/24204.35.32.1 to 204.35.32.254204.35.32.255254
34204.35.33.0/24204.35.33.1 to 204.35.33.254204.35.33.255254
35204.35.34.0/24204.35.34.1 to 204.35.34.254204.35.34.255254
36204.35.35.0/24204.35.35.1 to 204.35.35.254204.35.35.255254
37204.35.36.0/24204.35.36.1 to 204.35.36.254204.35.36.255254
38204.35.37.0/24204.35.37.1 to 204.35.37.254204.35.37.255254
39204.35.38.0/24204.35.38.1 to 204.35.38.254204.35.38.255254
40204.35.39.0/24204.35.39.1 to 204.35.39.254204.35.39.255254
41204.35.40.0/24204.35.40.1 to 204.35.40.254204.35.40.255254
42204.35.41.0/24204.35.41.1 to 204.35.41.254204.35.41.255254
43204.35.42.0/24204.35.42.1 to 204.35.42.254204.35.42.255254
44204.35.43.0/24204.35.43.1 to 204.35.43.254204.35.43.255254
45204.35.44.0/24204.35.44.1 to 204.35.44.254204.35.44.255254
46204.35.45.0/24204.35.45.1 to 204.35.45.254204.35.45.255254
47204.35.46.0/24204.35.46.1 to 204.35.46.254204.35.46.255254
48204.35.47.0/24204.35.47.1 to 204.35.47.254204.35.47.255254
49204.35.48.0/24204.35.48.1 to 204.35.48.254204.35.48.255254
50204.35.49.0/24204.35.49.1 to 204.35.49.254204.35.49.255254
51204.35.50.0/24204.35.50.1 to 204.35.50.254204.35.50.255254
52204.35.51.0/24204.35.51.1 to 204.35.51.254204.35.51.255254
53204.35.52.0/24204.35.52.1 to 204.35.52.254204.35.52.255254
54204.35.53.0/24204.35.53.1 to 204.35.53.254204.35.53.255254
55204.35.54.0/24204.35.54.1 to 204.35.54.254204.35.54.255254
56204.35.55.0/24204.35.55.1 to 204.35.55.254204.35.55.255254
57204.35.56.0/24204.35.56.1 to 204.35.56.254204.35.56.255254
58204.35.57.0/24204.35.57.1 to 204.35.57.254204.35.57.255254
59204.35.58.0/24204.35.58.1 to 204.35.58.254204.35.58.255254
60204.35.59.0/24204.35.59.1 to 204.35.59.254204.35.59.255254
61204.35.60.0/24204.35.60.1 to 204.35.60.254204.35.60.255254
62204.35.61.0/24204.35.61.1 to 204.35.61.254204.35.61.255254
63204.35.62.0/24204.35.62.1 to 204.35.62.254204.35.62.255254
64204.35.63.0/24204.35.63.1 to 204.35.63.254204.35.63.255254
65204.35.64.0/24204.35.64.1 to 204.35.64.254204.35.64.255254
66204.35.65.0/24204.35.65.1 to 204.35.65.254204.35.65.255254
67204.35.66.0/24204.35.66.1 to 204.35.66.254204.35.66.255254
68204.35.67.0/24204.35.67.1 to 204.35.67.254204.35.67.255254
69204.35.68.0/24204.35.68.1 to 204.35.68.254204.35.68.255254
70204.35.69.0/24204.35.69.1 to 204.35.69.254204.35.69.255254
71204.35.70.0/24204.35.70.1 to 204.35.70.254204.35.70.255254
72204.35.71.0/24204.35.71.1 to 204.35.71.254204.35.71.255254
73204.35.72.0/24204.35.72.1 to 204.35.72.254204.35.72.255254
74204.35.73.0/24204.35.73.1 to 204.35.73.254204.35.73.255254
75204.35.74.0/24204.35.74.1 to 204.35.74.254204.35.74.255254
76204.35.75.0/24204.35.75.1 to 204.35.75.254204.35.75.255254
77204.35.76.0/24204.35.76.1 to 204.35.76.254204.35.76.255254
78204.35.77.0/24204.35.77.1 to 204.35.77.254204.35.77.255254
79204.35.78.0/24204.35.78.1 to 204.35.78.254204.35.78.255254
80204.35.79.0/24204.35.79.1 to 204.35.79.254204.35.79.255254
81204.35.80.0/24204.35.80.1 to 204.35.80.254204.35.80.255254
82204.35.81.0/24204.35.81.1 to 204.35.81.254204.35.81.255254
83204.35.82.0/24204.35.82.1 to 204.35.82.254204.35.82.255254
84204.35.83.0/24204.35.83.1 to 204.35.83.254204.35.83.255254
85204.35.84.0/24204.35.84.1 to 204.35.84.254204.35.84.255254
86204.35.85.0/24204.35.85.1 to 204.35.85.254204.35.85.255254
87204.35.86.0/24204.35.86.1 to 204.35.86.254204.35.86.255254
88204.35.87.0/24204.35.87.1 to 204.35.87.254204.35.87.255254
89204.35.88.0/24204.35.88.1 to 204.35.88.254204.35.88.255254
90204.35.89.0/24204.35.89.1 to 204.35.89.254204.35.89.255254
91204.35.90.0/24204.35.90.1 to 204.35.90.254204.35.90.255254
92204.35.91.0/24204.35.91.1 to 204.35.91.254204.35.91.255254
93204.35.92.0/24204.35.92.1 to 204.35.92.254204.35.92.255254
94204.35.93.0/24204.35.93.1 to 204.35.93.254204.35.93.255254
95204.35.94.0/24204.35.94.1 to 204.35.94.254204.35.94.255254
96204.35.95.0/24204.35.95.1 to 204.35.95.254204.35.95.255254
97204.35.96.0/24204.35.96.1 to 204.35.96.254204.35.96.255254
98204.35.97.0/24204.35.97.1 to 204.35.97.254204.35.97.255254
99204.35.98.0/24204.35.98.1 to 204.35.98.254204.35.98.255254
100204.35.99.0/24204.35.99.1 to 204.35.99.254204.35.99.255254
101204.35.100.0/24204.35.100.1 to 204.35.100.254204.35.100.255254
102204.35.101.0/24204.35.101.1 to 204.35.101.254204.35.101.255254
103204.35.102.0/24204.35.102.1 to 204.35.102.254204.35.102.255254
104204.35.103.0/24204.35.103.1 to 204.35.103.254204.35.103.255254
105204.35.104.0/24204.35.104.1 to 204.35.104.254204.35.104.255254
106204.35.105.0/24204.35.105.1 to 204.35.105.254204.35.105.255254
107204.35.106.0/24204.35.106.1 to 204.35.106.254204.35.106.255254
108204.35.107.0/24204.35.107.1 to 204.35.107.254204.35.107.255254
109204.35.108.0/24204.35.108.1 to 204.35.108.254204.35.108.255254
110204.35.109.0/24204.35.109.1 to 204.35.109.254204.35.109.255254
111204.35.110.0/24204.35.110.1 to 204.35.110.254204.35.110.255254
112204.35.111.0/24204.35.111.1 to 204.35.111.254204.35.111.255254
113204.35.112.0/24204.35.112.1 to 204.35.112.254204.35.112.255254
114204.35.113.0/24204.35.113.1 to 204.35.113.254204.35.113.255254
115204.35.114.0/24204.35.114.1 to 204.35.114.254204.35.114.255254
116204.35.115.0/24204.35.115.1 to 204.35.115.254204.35.115.255254
117204.35.116.0/24204.35.116.1 to 204.35.116.254204.35.116.255254
118204.35.117.0/24204.35.117.1 to 204.35.117.254204.35.117.255254
119204.35.118.0/24204.35.118.1 to 204.35.118.254204.35.118.255254
120204.35.119.0/24204.35.119.1 to 204.35.119.254204.35.119.255254
121204.35.120.0/24204.35.120.1 to 204.35.120.254204.35.120.255254
122204.35.121.0/24204.35.121.1 to 204.35.121.254204.35.121.255254
123204.35.122.0/24204.35.122.1 to 204.35.122.254204.35.122.255254
124204.35.123.0/24204.35.123.1 to 204.35.123.254204.35.123.255254
125204.35.124.0/24204.35.124.1 to 204.35.124.254204.35.124.255254
126204.35.125.0/24204.35.125.1 to 204.35.125.254204.35.125.255254
127204.35.126.0/24204.35.126.1 to 204.35.126.254204.35.126.255254
128204.35.127.0/24204.35.127.1 to 204.35.127.254204.35.127.255254

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.