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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.

Network0.7.64.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
0.7.64.0
Broadcast address
0.7.127.255
First usable
0.7.64.1
Last usable
0.7.127.254
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
This network 0.0.0.0/8
Not routed; 0.0.0.0 means "any address" in settings
Old class
A (default /8)
As numbers
Hex 00074000 · Integer 475136 to 491519
Reverse DNS zones
64.7.0.in-addr.arpa
65.7.0.in-addr.arpa
66.7.0.in-addr.arpa
67.7.0.in-addr.arpa
68.7.0.in-addr.arpa
69.7.0.in-addr.arpa
70.7.0.in-addr.arpa
71.7.0.in-addr.arpa
72.7.0.in-addr.arpa
73.7.0.in-addr.arpa
74.7.0.in-addr.arpa
75.7.0.in-addr.arpa
76.7.0.in-addr.arpa
77.7.0.in-addr.arpa
78.7.0.in-addr.arpa
79.7.0.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
Address00000000.00000111.01000000.000000000.7.64.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network00000000.00000111.01000000.000000000.7.64.0
Broadcast00000000.00000111.01111111.111111110.7.127.255
Split into smaller subnets/29
/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)

0.7.64.0/18 makes 2,048 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
10.7.64.0/290.7.64.1 to 0.7.64.60.7.64.76
20.7.64.8/290.7.64.9 to 0.7.64.140.7.64.156
30.7.64.16/290.7.64.17 to 0.7.64.220.7.64.236
40.7.64.24/290.7.64.25 to 0.7.64.300.7.64.316
50.7.64.32/290.7.64.33 to 0.7.64.380.7.64.396
60.7.64.40/290.7.64.41 to 0.7.64.460.7.64.476
70.7.64.48/290.7.64.49 to 0.7.64.540.7.64.556
80.7.64.56/290.7.64.57 to 0.7.64.620.7.64.636
90.7.64.64/290.7.64.65 to 0.7.64.700.7.64.716
100.7.64.72/290.7.64.73 to 0.7.64.780.7.64.796
110.7.64.80/290.7.64.81 to 0.7.64.860.7.64.876
120.7.64.88/290.7.64.89 to 0.7.64.940.7.64.956
130.7.64.96/290.7.64.97 to 0.7.64.1020.7.64.1036
140.7.64.104/290.7.64.105 to 0.7.64.1100.7.64.1116
150.7.64.112/290.7.64.113 to 0.7.64.1180.7.64.1196
160.7.64.120/290.7.64.121 to 0.7.64.1260.7.64.1276
170.7.64.128/290.7.64.129 to 0.7.64.1340.7.64.1356
180.7.64.136/290.7.64.137 to 0.7.64.1420.7.64.1436
190.7.64.144/290.7.64.145 to 0.7.64.1500.7.64.1516
200.7.64.152/290.7.64.153 to 0.7.64.1580.7.64.1596
210.7.64.160/290.7.64.161 to 0.7.64.1660.7.64.1676
220.7.64.168/290.7.64.169 to 0.7.64.1740.7.64.1756
230.7.64.176/290.7.64.177 to 0.7.64.1820.7.64.1836
240.7.64.184/290.7.64.185 to 0.7.64.1900.7.64.1916
250.7.64.192/290.7.64.193 to 0.7.64.1980.7.64.1996
260.7.64.200/290.7.64.201 to 0.7.64.2060.7.64.2076
270.7.64.208/290.7.64.209 to 0.7.64.2140.7.64.2156
280.7.64.216/290.7.64.217 to 0.7.64.2220.7.64.2236
290.7.64.224/290.7.64.225 to 0.7.64.2300.7.64.2316
300.7.64.232/290.7.64.233 to 0.7.64.2380.7.64.2396
310.7.64.240/290.7.64.241 to 0.7.64.2460.7.64.2476
320.7.64.248/290.7.64.249 to 0.7.64.2540.7.64.2556
330.7.65.0/290.7.65.1 to 0.7.65.60.7.65.76
340.7.65.8/290.7.65.9 to 0.7.65.140.7.65.156
350.7.65.16/290.7.65.17 to 0.7.65.220.7.65.236
360.7.65.24/290.7.65.25 to 0.7.65.300.7.65.316
370.7.65.32/290.7.65.33 to 0.7.65.380.7.65.396
380.7.65.40/290.7.65.41 to 0.7.65.460.7.65.476
390.7.65.48/290.7.65.49 to 0.7.65.540.7.65.556
400.7.65.56/290.7.65.57 to 0.7.65.620.7.65.636
410.7.65.64/290.7.65.65 to 0.7.65.700.7.65.716
420.7.65.72/290.7.65.73 to 0.7.65.780.7.65.796
430.7.65.80/290.7.65.81 to 0.7.65.860.7.65.876
440.7.65.88/290.7.65.89 to 0.7.65.940.7.65.956
450.7.65.96/290.7.65.97 to 0.7.65.1020.7.65.1036
460.7.65.104/290.7.65.105 to 0.7.65.1100.7.65.1116
470.7.65.112/290.7.65.113 to 0.7.65.1180.7.65.1196
480.7.65.120/290.7.65.121 to 0.7.65.1260.7.65.1276
490.7.65.128/290.7.65.129 to 0.7.65.1340.7.65.1356
500.7.65.136/290.7.65.137 to 0.7.65.1420.7.65.1436
510.7.65.144/290.7.65.145 to 0.7.65.1500.7.65.1516
520.7.65.152/290.7.65.153 to 0.7.65.1580.7.65.1596
530.7.65.160/290.7.65.161 to 0.7.65.1660.7.65.1676
540.7.65.168/290.7.65.169 to 0.7.65.1740.7.65.1756
550.7.65.176/290.7.65.177 to 0.7.65.1820.7.65.1836
560.7.65.184/290.7.65.185 to 0.7.65.1900.7.65.1916
570.7.65.192/290.7.65.193 to 0.7.65.1980.7.65.1996
580.7.65.200/290.7.65.201 to 0.7.65.2060.7.65.2076
590.7.65.208/290.7.65.209 to 0.7.65.2140.7.65.2156
600.7.65.216/290.7.65.217 to 0.7.65.2220.7.65.2236
610.7.65.224/290.7.65.225 to 0.7.65.2300.7.65.2316
620.7.65.232/290.7.65.233 to 0.7.65.2380.7.65.2396
630.7.65.240/290.7.65.241 to 0.7.65.2460.7.65.2476
640.7.65.248/290.7.65.249 to 0.7.65.2540.7.65.2556
650.7.66.0/290.7.66.1 to 0.7.66.60.7.66.76
660.7.66.8/290.7.66.9 to 0.7.66.140.7.66.156
670.7.66.16/290.7.66.17 to 0.7.66.220.7.66.236
680.7.66.24/290.7.66.25 to 0.7.66.300.7.66.316
690.7.66.32/290.7.66.33 to 0.7.66.380.7.66.396
700.7.66.40/290.7.66.41 to 0.7.66.460.7.66.476
710.7.66.48/290.7.66.49 to 0.7.66.540.7.66.556
720.7.66.56/290.7.66.57 to 0.7.66.620.7.66.636
730.7.66.64/290.7.66.65 to 0.7.66.700.7.66.716
740.7.66.72/290.7.66.73 to 0.7.66.780.7.66.796
750.7.66.80/290.7.66.81 to 0.7.66.860.7.66.876
760.7.66.88/290.7.66.89 to 0.7.66.940.7.66.956
770.7.66.96/290.7.66.97 to 0.7.66.1020.7.66.1036
780.7.66.104/290.7.66.105 to 0.7.66.1100.7.66.1116
790.7.66.112/290.7.66.113 to 0.7.66.1180.7.66.1196
800.7.66.120/290.7.66.121 to 0.7.66.1260.7.66.1276
810.7.66.128/290.7.66.129 to 0.7.66.1340.7.66.1356
820.7.66.136/290.7.66.137 to 0.7.66.1420.7.66.1436
830.7.66.144/290.7.66.145 to 0.7.66.1500.7.66.1516
840.7.66.152/290.7.66.153 to 0.7.66.1580.7.66.1596
850.7.66.160/290.7.66.161 to 0.7.66.1660.7.66.1676
860.7.66.168/290.7.66.169 to 0.7.66.1740.7.66.1756
870.7.66.176/290.7.66.177 to 0.7.66.1820.7.66.1836
880.7.66.184/290.7.66.185 to 0.7.66.1900.7.66.1916
890.7.66.192/290.7.66.193 to 0.7.66.1980.7.66.1996
900.7.66.200/290.7.66.201 to 0.7.66.2060.7.66.2076
910.7.66.208/290.7.66.209 to 0.7.66.2140.7.66.2156
920.7.66.216/290.7.66.217 to 0.7.66.2220.7.66.2236
930.7.66.224/290.7.66.225 to 0.7.66.2300.7.66.2316
940.7.66.232/290.7.66.233 to 0.7.66.2380.7.66.2396
950.7.66.240/290.7.66.241 to 0.7.66.2460.7.66.2476
960.7.66.248/290.7.66.249 to 0.7.66.2540.7.66.2556
970.7.67.0/290.7.67.1 to 0.7.67.60.7.67.76
980.7.67.8/290.7.67.9 to 0.7.67.140.7.67.156
990.7.67.16/290.7.67.17 to 0.7.67.220.7.67.236
1000.7.67.24/290.7.67.25 to 0.7.67.300.7.67.316
1010.7.67.32/290.7.67.33 to 0.7.67.380.7.67.396
1020.7.67.40/290.7.67.41 to 0.7.67.460.7.67.476
1030.7.67.48/290.7.67.49 to 0.7.67.540.7.67.556
1040.7.67.56/290.7.67.57 to 0.7.67.620.7.67.636
1050.7.67.64/290.7.67.65 to 0.7.67.700.7.67.716
1060.7.67.72/290.7.67.73 to 0.7.67.780.7.67.796
1070.7.67.80/290.7.67.81 to 0.7.67.860.7.67.876
1080.7.67.88/290.7.67.89 to 0.7.67.940.7.67.956
1090.7.67.96/290.7.67.97 to 0.7.67.1020.7.67.1036
1100.7.67.104/290.7.67.105 to 0.7.67.1100.7.67.1116
1110.7.67.112/290.7.67.113 to 0.7.67.1180.7.67.1196
1120.7.67.120/290.7.67.121 to 0.7.67.1260.7.67.1276
1130.7.67.128/290.7.67.129 to 0.7.67.1340.7.67.1356
1140.7.67.136/290.7.67.137 to 0.7.67.1420.7.67.1436
1150.7.67.144/290.7.67.145 to 0.7.67.1500.7.67.1516
1160.7.67.152/290.7.67.153 to 0.7.67.1580.7.67.1596
1170.7.67.160/290.7.67.161 to 0.7.67.1660.7.67.1676
1180.7.67.168/290.7.67.169 to 0.7.67.1740.7.67.1756
1190.7.67.176/290.7.67.177 to 0.7.67.1820.7.67.1836
1200.7.67.184/290.7.67.185 to 0.7.67.1900.7.67.1916
1210.7.67.192/290.7.67.193 to 0.7.67.1980.7.67.1996
1220.7.67.200/290.7.67.201 to 0.7.67.2060.7.67.2076
1230.7.67.208/290.7.67.209 to 0.7.67.2140.7.67.2156
1240.7.67.216/290.7.67.217 to 0.7.67.2220.7.67.2236
1250.7.67.224/290.7.67.225 to 0.7.67.2300.7.67.2316
1260.7.67.232/290.7.67.233 to 0.7.67.2380.7.67.2396
1270.7.67.240/290.7.67.241 to 0.7.67.2460.7.67.2476
1280.7.67.248/290.7.67.249 to 0.7.67.2540.7.67.2556
1290.7.68.0/290.7.68.1 to 0.7.68.60.7.68.76
1300.7.68.8/290.7.68.9 to 0.7.68.140.7.68.156
1310.7.68.16/290.7.68.17 to 0.7.68.220.7.68.236
1320.7.68.24/290.7.68.25 to 0.7.68.300.7.68.316
1330.7.68.32/290.7.68.33 to 0.7.68.380.7.68.396
1340.7.68.40/290.7.68.41 to 0.7.68.460.7.68.476
1350.7.68.48/290.7.68.49 to 0.7.68.540.7.68.556
1360.7.68.56/290.7.68.57 to 0.7.68.620.7.68.636
1370.7.68.64/290.7.68.65 to 0.7.68.700.7.68.716
1380.7.68.72/290.7.68.73 to 0.7.68.780.7.68.796
1390.7.68.80/290.7.68.81 to 0.7.68.860.7.68.876
1400.7.68.88/290.7.68.89 to 0.7.68.940.7.68.956
1410.7.68.96/290.7.68.97 to 0.7.68.1020.7.68.1036
1420.7.68.104/290.7.68.105 to 0.7.68.1100.7.68.1116
1430.7.68.112/290.7.68.113 to 0.7.68.1180.7.68.1196
1440.7.68.120/290.7.68.121 to 0.7.68.1260.7.68.1276
1450.7.68.128/290.7.68.129 to 0.7.68.1340.7.68.1356
1460.7.68.136/290.7.68.137 to 0.7.68.1420.7.68.1436
1470.7.68.144/290.7.68.145 to 0.7.68.1500.7.68.1516
1480.7.68.152/290.7.68.153 to 0.7.68.1580.7.68.1596
1490.7.68.160/290.7.68.161 to 0.7.68.1660.7.68.1676
1500.7.68.168/290.7.68.169 to 0.7.68.1740.7.68.1756
1510.7.68.176/290.7.68.177 to 0.7.68.1820.7.68.1836
1520.7.68.184/290.7.68.185 to 0.7.68.1900.7.68.1916
1530.7.68.192/290.7.68.193 to 0.7.68.1980.7.68.1996
1540.7.68.200/290.7.68.201 to 0.7.68.2060.7.68.2076
1550.7.68.208/290.7.68.209 to 0.7.68.2140.7.68.2156
1560.7.68.216/290.7.68.217 to 0.7.68.2220.7.68.2236
1570.7.68.224/290.7.68.225 to 0.7.68.2300.7.68.2316
1580.7.68.232/290.7.68.233 to 0.7.68.2380.7.68.2396
1590.7.68.240/290.7.68.241 to 0.7.68.2460.7.68.2476
1600.7.68.248/290.7.68.249 to 0.7.68.2540.7.68.2556
1610.7.69.0/290.7.69.1 to 0.7.69.60.7.69.76
1620.7.69.8/290.7.69.9 to 0.7.69.140.7.69.156
1630.7.69.16/290.7.69.17 to 0.7.69.220.7.69.236
1640.7.69.24/290.7.69.25 to 0.7.69.300.7.69.316
1650.7.69.32/290.7.69.33 to 0.7.69.380.7.69.396
1660.7.69.40/290.7.69.41 to 0.7.69.460.7.69.476
1670.7.69.48/290.7.69.49 to 0.7.69.540.7.69.556
1680.7.69.56/290.7.69.57 to 0.7.69.620.7.69.636
1690.7.69.64/290.7.69.65 to 0.7.69.700.7.69.716
1700.7.69.72/290.7.69.73 to 0.7.69.780.7.69.796
1710.7.69.80/290.7.69.81 to 0.7.69.860.7.69.876
1720.7.69.88/290.7.69.89 to 0.7.69.940.7.69.956
1730.7.69.96/290.7.69.97 to 0.7.69.1020.7.69.1036
1740.7.69.104/290.7.69.105 to 0.7.69.1100.7.69.1116
1750.7.69.112/290.7.69.113 to 0.7.69.1180.7.69.1196
1760.7.69.120/290.7.69.121 to 0.7.69.1260.7.69.1276
1770.7.69.128/290.7.69.129 to 0.7.69.1340.7.69.1356
1780.7.69.136/290.7.69.137 to 0.7.69.1420.7.69.1436
1790.7.69.144/290.7.69.145 to 0.7.69.1500.7.69.1516
1800.7.69.152/290.7.69.153 to 0.7.69.1580.7.69.1596
1810.7.69.160/290.7.69.161 to 0.7.69.1660.7.69.1676
1820.7.69.168/290.7.69.169 to 0.7.69.1740.7.69.1756
1830.7.69.176/290.7.69.177 to 0.7.69.1820.7.69.1836
1840.7.69.184/290.7.69.185 to 0.7.69.1900.7.69.1916
1850.7.69.192/290.7.69.193 to 0.7.69.1980.7.69.1996
1860.7.69.200/290.7.69.201 to 0.7.69.2060.7.69.2076
1870.7.69.208/290.7.69.209 to 0.7.69.2140.7.69.2156
1880.7.69.216/290.7.69.217 to 0.7.69.2220.7.69.2236
1890.7.69.224/290.7.69.225 to 0.7.69.2300.7.69.2316
1900.7.69.232/290.7.69.233 to 0.7.69.2380.7.69.2396
1910.7.69.240/290.7.69.241 to 0.7.69.2460.7.69.2476
1920.7.69.248/290.7.69.249 to 0.7.69.2540.7.69.2556
1930.7.70.0/290.7.70.1 to 0.7.70.60.7.70.76
1940.7.70.8/290.7.70.9 to 0.7.70.140.7.70.156
1950.7.70.16/290.7.70.17 to 0.7.70.220.7.70.236
1960.7.70.24/290.7.70.25 to 0.7.70.300.7.70.316
1970.7.70.32/290.7.70.33 to 0.7.70.380.7.70.396
1980.7.70.40/290.7.70.41 to 0.7.70.460.7.70.476
1990.7.70.48/290.7.70.49 to 0.7.70.540.7.70.556
2000.7.70.56/290.7.70.57 to 0.7.70.620.7.70.636
2010.7.70.64/290.7.70.65 to 0.7.70.700.7.70.716
2020.7.70.72/290.7.70.73 to 0.7.70.780.7.70.796
2030.7.70.80/290.7.70.81 to 0.7.70.860.7.70.876
2040.7.70.88/290.7.70.89 to 0.7.70.940.7.70.956
2050.7.70.96/290.7.70.97 to 0.7.70.1020.7.70.1036
2060.7.70.104/290.7.70.105 to 0.7.70.1100.7.70.1116
2070.7.70.112/290.7.70.113 to 0.7.70.1180.7.70.1196
2080.7.70.120/290.7.70.121 to 0.7.70.1260.7.70.1276
2090.7.70.128/290.7.70.129 to 0.7.70.1340.7.70.1356
2100.7.70.136/290.7.70.137 to 0.7.70.1420.7.70.1436
2110.7.70.144/290.7.70.145 to 0.7.70.1500.7.70.1516
2120.7.70.152/290.7.70.153 to 0.7.70.1580.7.70.1596
2130.7.70.160/290.7.70.161 to 0.7.70.1660.7.70.1676
2140.7.70.168/290.7.70.169 to 0.7.70.1740.7.70.1756
2150.7.70.176/290.7.70.177 to 0.7.70.1820.7.70.1836
2160.7.70.184/290.7.70.185 to 0.7.70.1900.7.70.1916
2170.7.70.192/290.7.70.193 to 0.7.70.1980.7.70.1996
2180.7.70.200/290.7.70.201 to 0.7.70.2060.7.70.2076
2190.7.70.208/290.7.70.209 to 0.7.70.2140.7.70.2156
2200.7.70.216/290.7.70.217 to 0.7.70.2220.7.70.2236
2210.7.70.224/290.7.70.225 to 0.7.70.2300.7.70.2316
2220.7.70.232/290.7.70.233 to 0.7.70.2380.7.70.2396
2230.7.70.240/290.7.70.241 to 0.7.70.2460.7.70.2476
2240.7.70.248/290.7.70.249 to 0.7.70.2540.7.70.2556
2250.7.71.0/290.7.71.1 to 0.7.71.60.7.71.76
2260.7.71.8/290.7.71.9 to 0.7.71.140.7.71.156
2270.7.71.16/290.7.71.17 to 0.7.71.220.7.71.236
2280.7.71.24/290.7.71.25 to 0.7.71.300.7.71.316
2290.7.71.32/290.7.71.33 to 0.7.71.380.7.71.396
2300.7.71.40/290.7.71.41 to 0.7.71.460.7.71.476
2310.7.71.48/290.7.71.49 to 0.7.71.540.7.71.556
2320.7.71.56/290.7.71.57 to 0.7.71.620.7.71.636
2330.7.71.64/290.7.71.65 to 0.7.71.700.7.71.716
2340.7.71.72/290.7.71.73 to 0.7.71.780.7.71.796
2350.7.71.80/290.7.71.81 to 0.7.71.860.7.71.876
2360.7.71.88/290.7.71.89 to 0.7.71.940.7.71.956
2370.7.71.96/290.7.71.97 to 0.7.71.1020.7.71.1036
2380.7.71.104/290.7.71.105 to 0.7.71.1100.7.71.1116
2390.7.71.112/290.7.71.113 to 0.7.71.1180.7.71.1196
2400.7.71.120/290.7.71.121 to 0.7.71.1260.7.71.1276
2410.7.71.128/290.7.71.129 to 0.7.71.1340.7.71.1356
2420.7.71.136/290.7.71.137 to 0.7.71.1420.7.71.1436
2430.7.71.144/290.7.71.145 to 0.7.71.1500.7.71.1516
2440.7.71.152/290.7.71.153 to 0.7.71.1580.7.71.1596
2450.7.71.160/290.7.71.161 to 0.7.71.1660.7.71.1676
2460.7.71.168/290.7.71.169 to 0.7.71.1740.7.71.1756
2470.7.71.176/290.7.71.177 to 0.7.71.1820.7.71.1836
2480.7.71.184/290.7.71.185 to 0.7.71.1900.7.71.1916
2490.7.71.192/290.7.71.193 to 0.7.71.1980.7.71.1996
2500.7.71.200/290.7.71.201 to 0.7.71.2060.7.71.2076
2510.7.71.208/290.7.71.209 to 0.7.71.2140.7.71.2156
2520.7.71.216/290.7.71.217 to 0.7.71.2220.7.71.2236
2530.7.71.224/290.7.71.225 to 0.7.71.2300.7.71.2316
2540.7.71.232/290.7.71.233 to 0.7.71.2380.7.71.2396
2550.7.71.240/290.7.71.241 to 0.7.71.2460.7.71.2476
2560.7.71.248/290.7.71.249 to 0.7.71.2540.7.71.2556

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.