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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.

Network73.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
73.0.0.0
Broadcast address
73.127.255.255
First usable
73.0.0.1
Last usable
73.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
A (default /8)
As numbers
Hex 49000000 · Integer 1224736768 to 1233125375
Reverse DNS zones
0.73.in-addr.arpa
1.73.in-addr.arpa
2.73.in-addr.arpa
3.73.in-addr.arpa
4.73.in-addr.arpa
5.73.in-addr.arpa
6.73.in-addr.arpa
7.73.in-addr.arpa
8.73.in-addr.arpa
9.73.in-addr.arpa
10.73.in-addr.arpa
11.73.in-addr.arpa
12.73.in-addr.arpa
13.73.in-addr.arpa
14.73.in-addr.arpa
15.73.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01001001.00000000.00000000.0000000073.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01001001.00000000.00000000.0000000073.0.0.0
Broadcast01001001.01111111.11111111.1111111173.127.255.255
Split into smaller subnets/17
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

73.0.0.0/9 makes 256 subnets of /17.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
173.0.0.0/1773.0.0.1 to 73.0.127.25473.0.127.25532,766
273.0.128.0/1773.0.128.1 to 73.0.255.25473.0.255.25532,766
373.1.0.0/1773.1.0.1 to 73.1.127.25473.1.127.25532,766
473.1.128.0/1773.1.128.1 to 73.1.255.25473.1.255.25532,766
573.2.0.0/1773.2.0.1 to 73.2.127.25473.2.127.25532,766
673.2.128.0/1773.2.128.1 to 73.2.255.25473.2.255.25532,766
773.3.0.0/1773.3.0.1 to 73.3.127.25473.3.127.25532,766
873.3.128.0/1773.3.128.1 to 73.3.255.25473.3.255.25532,766
973.4.0.0/1773.4.0.1 to 73.4.127.25473.4.127.25532,766
1073.4.128.0/1773.4.128.1 to 73.4.255.25473.4.255.25532,766
1173.5.0.0/1773.5.0.1 to 73.5.127.25473.5.127.25532,766
1273.5.128.0/1773.5.128.1 to 73.5.255.25473.5.255.25532,766
1373.6.0.0/1773.6.0.1 to 73.6.127.25473.6.127.25532,766
1473.6.128.0/1773.6.128.1 to 73.6.255.25473.6.255.25532,766
1573.7.0.0/1773.7.0.1 to 73.7.127.25473.7.127.25532,766
1673.7.128.0/1773.7.128.1 to 73.7.255.25473.7.255.25532,766
1773.8.0.0/1773.8.0.1 to 73.8.127.25473.8.127.25532,766
1873.8.128.0/1773.8.128.1 to 73.8.255.25473.8.255.25532,766
1973.9.0.0/1773.9.0.1 to 73.9.127.25473.9.127.25532,766
2073.9.128.0/1773.9.128.1 to 73.9.255.25473.9.255.25532,766
2173.10.0.0/1773.10.0.1 to 73.10.127.25473.10.127.25532,766
2273.10.128.0/1773.10.128.1 to 73.10.255.25473.10.255.25532,766
2373.11.0.0/1773.11.0.1 to 73.11.127.25473.11.127.25532,766
2473.11.128.0/1773.11.128.1 to 73.11.255.25473.11.255.25532,766
2573.12.0.0/1773.12.0.1 to 73.12.127.25473.12.127.25532,766
2673.12.128.0/1773.12.128.1 to 73.12.255.25473.12.255.25532,766
2773.13.0.0/1773.13.0.1 to 73.13.127.25473.13.127.25532,766
2873.13.128.0/1773.13.128.1 to 73.13.255.25473.13.255.25532,766
2973.14.0.0/1773.14.0.1 to 73.14.127.25473.14.127.25532,766
3073.14.128.0/1773.14.128.1 to 73.14.255.25473.14.255.25532,766
3173.15.0.0/1773.15.0.1 to 73.15.127.25473.15.127.25532,766
3273.15.128.0/1773.15.128.1 to 73.15.255.25473.15.255.25532,766
3373.16.0.0/1773.16.0.1 to 73.16.127.25473.16.127.25532,766
3473.16.128.0/1773.16.128.1 to 73.16.255.25473.16.255.25532,766
3573.17.0.0/1773.17.0.1 to 73.17.127.25473.17.127.25532,766
3673.17.128.0/1773.17.128.1 to 73.17.255.25473.17.255.25532,766
3773.18.0.0/1773.18.0.1 to 73.18.127.25473.18.127.25532,766
3873.18.128.0/1773.18.128.1 to 73.18.255.25473.18.255.25532,766
3973.19.0.0/1773.19.0.1 to 73.19.127.25473.19.127.25532,766
4073.19.128.0/1773.19.128.1 to 73.19.255.25473.19.255.25532,766
4173.20.0.0/1773.20.0.1 to 73.20.127.25473.20.127.25532,766
4273.20.128.0/1773.20.128.1 to 73.20.255.25473.20.255.25532,766
4373.21.0.0/1773.21.0.1 to 73.21.127.25473.21.127.25532,766
4473.21.128.0/1773.21.128.1 to 73.21.255.25473.21.255.25532,766
4573.22.0.0/1773.22.0.1 to 73.22.127.25473.22.127.25532,766
4673.22.128.0/1773.22.128.1 to 73.22.255.25473.22.255.25532,766
4773.23.0.0/1773.23.0.1 to 73.23.127.25473.23.127.25532,766
4873.23.128.0/1773.23.128.1 to 73.23.255.25473.23.255.25532,766
4973.24.0.0/1773.24.0.1 to 73.24.127.25473.24.127.25532,766
5073.24.128.0/1773.24.128.1 to 73.24.255.25473.24.255.25532,766
5173.25.0.0/1773.25.0.1 to 73.25.127.25473.25.127.25532,766
5273.25.128.0/1773.25.128.1 to 73.25.255.25473.25.255.25532,766
5373.26.0.0/1773.26.0.1 to 73.26.127.25473.26.127.25532,766
5473.26.128.0/1773.26.128.1 to 73.26.255.25473.26.255.25532,766
5573.27.0.0/1773.27.0.1 to 73.27.127.25473.27.127.25532,766
5673.27.128.0/1773.27.128.1 to 73.27.255.25473.27.255.25532,766
5773.28.0.0/1773.28.0.1 to 73.28.127.25473.28.127.25532,766
5873.28.128.0/1773.28.128.1 to 73.28.255.25473.28.255.25532,766
5973.29.0.0/1773.29.0.1 to 73.29.127.25473.29.127.25532,766
6073.29.128.0/1773.29.128.1 to 73.29.255.25473.29.255.25532,766
6173.30.0.0/1773.30.0.1 to 73.30.127.25473.30.127.25532,766
6273.30.128.0/1773.30.128.1 to 73.30.255.25473.30.255.25532,766
6373.31.0.0/1773.31.0.1 to 73.31.127.25473.31.127.25532,766
6473.31.128.0/1773.31.128.1 to 73.31.255.25473.31.255.25532,766
6573.32.0.0/1773.32.0.1 to 73.32.127.25473.32.127.25532,766
6673.32.128.0/1773.32.128.1 to 73.32.255.25473.32.255.25532,766
6773.33.0.0/1773.33.0.1 to 73.33.127.25473.33.127.25532,766
6873.33.128.0/1773.33.128.1 to 73.33.255.25473.33.255.25532,766
6973.34.0.0/1773.34.0.1 to 73.34.127.25473.34.127.25532,766
7073.34.128.0/1773.34.128.1 to 73.34.255.25473.34.255.25532,766
7173.35.0.0/1773.35.0.1 to 73.35.127.25473.35.127.25532,766
7273.35.128.0/1773.35.128.1 to 73.35.255.25473.35.255.25532,766
7373.36.0.0/1773.36.0.1 to 73.36.127.25473.36.127.25532,766
7473.36.128.0/1773.36.128.1 to 73.36.255.25473.36.255.25532,766
7573.37.0.0/1773.37.0.1 to 73.37.127.25473.37.127.25532,766
7673.37.128.0/1773.37.128.1 to 73.37.255.25473.37.255.25532,766
7773.38.0.0/1773.38.0.1 to 73.38.127.25473.38.127.25532,766
7873.38.128.0/1773.38.128.1 to 73.38.255.25473.38.255.25532,766
7973.39.0.0/1773.39.0.1 to 73.39.127.25473.39.127.25532,766
8073.39.128.0/1773.39.128.1 to 73.39.255.25473.39.255.25532,766
8173.40.0.0/1773.40.0.1 to 73.40.127.25473.40.127.25532,766
8273.40.128.0/1773.40.128.1 to 73.40.255.25473.40.255.25532,766
8373.41.0.0/1773.41.0.1 to 73.41.127.25473.41.127.25532,766
8473.41.128.0/1773.41.128.1 to 73.41.255.25473.41.255.25532,766
8573.42.0.0/1773.42.0.1 to 73.42.127.25473.42.127.25532,766
8673.42.128.0/1773.42.128.1 to 73.42.255.25473.42.255.25532,766
8773.43.0.0/1773.43.0.1 to 73.43.127.25473.43.127.25532,766
8873.43.128.0/1773.43.128.1 to 73.43.255.25473.43.255.25532,766
8973.44.0.0/1773.44.0.1 to 73.44.127.25473.44.127.25532,766
9073.44.128.0/1773.44.128.1 to 73.44.255.25473.44.255.25532,766
9173.45.0.0/1773.45.0.1 to 73.45.127.25473.45.127.25532,766
9273.45.128.0/1773.45.128.1 to 73.45.255.25473.45.255.25532,766
9373.46.0.0/1773.46.0.1 to 73.46.127.25473.46.127.25532,766
9473.46.128.0/1773.46.128.1 to 73.46.255.25473.46.255.25532,766
9573.47.0.0/1773.47.0.1 to 73.47.127.25473.47.127.25532,766
9673.47.128.0/1773.47.128.1 to 73.47.255.25473.47.255.25532,766
9773.48.0.0/1773.48.0.1 to 73.48.127.25473.48.127.25532,766
9873.48.128.0/1773.48.128.1 to 73.48.255.25473.48.255.25532,766
9973.49.0.0/1773.49.0.1 to 73.49.127.25473.49.127.25532,766
10073.49.128.0/1773.49.128.1 to 73.49.255.25473.49.255.25532,766
10173.50.0.0/1773.50.0.1 to 73.50.127.25473.50.127.25532,766
10273.50.128.0/1773.50.128.1 to 73.50.255.25473.50.255.25532,766
10373.51.0.0/1773.51.0.1 to 73.51.127.25473.51.127.25532,766
10473.51.128.0/1773.51.128.1 to 73.51.255.25473.51.255.25532,766
10573.52.0.0/1773.52.0.1 to 73.52.127.25473.52.127.25532,766
10673.52.128.0/1773.52.128.1 to 73.52.255.25473.52.255.25532,766
10773.53.0.0/1773.53.0.1 to 73.53.127.25473.53.127.25532,766
10873.53.128.0/1773.53.128.1 to 73.53.255.25473.53.255.25532,766
10973.54.0.0/1773.54.0.1 to 73.54.127.25473.54.127.25532,766
11073.54.128.0/1773.54.128.1 to 73.54.255.25473.54.255.25532,766
11173.55.0.0/1773.55.0.1 to 73.55.127.25473.55.127.25532,766
11273.55.128.0/1773.55.128.1 to 73.55.255.25473.55.255.25532,766
11373.56.0.0/1773.56.0.1 to 73.56.127.25473.56.127.25532,766
11473.56.128.0/1773.56.128.1 to 73.56.255.25473.56.255.25532,766
11573.57.0.0/1773.57.0.1 to 73.57.127.25473.57.127.25532,766
11673.57.128.0/1773.57.128.1 to 73.57.255.25473.57.255.25532,766
11773.58.0.0/1773.58.0.1 to 73.58.127.25473.58.127.25532,766
11873.58.128.0/1773.58.128.1 to 73.58.255.25473.58.255.25532,766
11973.59.0.0/1773.59.0.1 to 73.59.127.25473.59.127.25532,766
12073.59.128.0/1773.59.128.1 to 73.59.255.25473.59.255.25532,766
12173.60.0.0/1773.60.0.1 to 73.60.127.25473.60.127.25532,766
12273.60.128.0/1773.60.128.1 to 73.60.255.25473.60.255.25532,766
12373.61.0.0/1773.61.0.1 to 73.61.127.25473.61.127.25532,766
12473.61.128.0/1773.61.128.1 to 73.61.255.25473.61.255.25532,766
12573.62.0.0/1773.62.0.1 to 73.62.127.25473.62.127.25532,766
12673.62.128.0/1773.62.128.1 to 73.62.255.25473.62.255.25532,766
12773.63.0.0/1773.63.0.1 to 73.63.127.25473.63.127.25532,766
12873.63.128.0/1773.63.128.1 to 73.63.255.25473.63.255.25532,766
12973.64.0.0/1773.64.0.1 to 73.64.127.25473.64.127.25532,766
13073.64.128.0/1773.64.128.1 to 73.64.255.25473.64.255.25532,766
13173.65.0.0/1773.65.0.1 to 73.65.127.25473.65.127.25532,766
13273.65.128.0/1773.65.128.1 to 73.65.255.25473.65.255.25532,766
13373.66.0.0/1773.66.0.1 to 73.66.127.25473.66.127.25532,766
13473.66.128.0/1773.66.128.1 to 73.66.255.25473.66.255.25532,766
13573.67.0.0/1773.67.0.1 to 73.67.127.25473.67.127.25532,766
13673.67.128.0/1773.67.128.1 to 73.67.255.25473.67.255.25532,766
13773.68.0.0/1773.68.0.1 to 73.68.127.25473.68.127.25532,766
13873.68.128.0/1773.68.128.1 to 73.68.255.25473.68.255.25532,766
13973.69.0.0/1773.69.0.1 to 73.69.127.25473.69.127.25532,766
14073.69.128.0/1773.69.128.1 to 73.69.255.25473.69.255.25532,766
14173.70.0.0/1773.70.0.1 to 73.70.127.25473.70.127.25532,766
14273.70.128.0/1773.70.128.1 to 73.70.255.25473.70.255.25532,766
14373.71.0.0/1773.71.0.1 to 73.71.127.25473.71.127.25532,766
14473.71.128.0/1773.71.128.1 to 73.71.255.25473.71.255.25532,766
14573.72.0.0/1773.72.0.1 to 73.72.127.25473.72.127.25532,766
14673.72.128.0/1773.72.128.1 to 73.72.255.25473.72.255.25532,766
14773.73.0.0/1773.73.0.1 to 73.73.127.25473.73.127.25532,766
14873.73.128.0/1773.73.128.1 to 73.73.255.25473.73.255.25532,766
14973.74.0.0/1773.74.0.1 to 73.74.127.25473.74.127.25532,766
15073.74.128.0/1773.74.128.1 to 73.74.255.25473.74.255.25532,766
15173.75.0.0/1773.75.0.1 to 73.75.127.25473.75.127.25532,766
15273.75.128.0/1773.75.128.1 to 73.75.255.25473.75.255.25532,766
15373.76.0.0/1773.76.0.1 to 73.76.127.25473.76.127.25532,766
15473.76.128.0/1773.76.128.1 to 73.76.255.25473.76.255.25532,766
15573.77.0.0/1773.77.0.1 to 73.77.127.25473.77.127.25532,766
15673.77.128.0/1773.77.128.1 to 73.77.255.25473.77.255.25532,766
15773.78.0.0/1773.78.0.1 to 73.78.127.25473.78.127.25532,766
15873.78.128.0/1773.78.128.1 to 73.78.255.25473.78.255.25532,766
15973.79.0.0/1773.79.0.1 to 73.79.127.25473.79.127.25532,766
16073.79.128.0/1773.79.128.1 to 73.79.255.25473.79.255.25532,766
16173.80.0.0/1773.80.0.1 to 73.80.127.25473.80.127.25532,766
16273.80.128.0/1773.80.128.1 to 73.80.255.25473.80.255.25532,766
16373.81.0.0/1773.81.0.1 to 73.81.127.25473.81.127.25532,766
16473.81.128.0/1773.81.128.1 to 73.81.255.25473.81.255.25532,766
16573.82.0.0/1773.82.0.1 to 73.82.127.25473.82.127.25532,766
16673.82.128.0/1773.82.128.1 to 73.82.255.25473.82.255.25532,766
16773.83.0.0/1773.83.0.1 to 73.83.127.25473.83.127.25532,766
16873.83.128.0/1773.83.128.1 to 73.83.255.25473.83.255.25532,766
16973.84.0.0/1773.84.0.1 to 73.84.127.25473.84.127.25532,766
17073.84.128.0/1773.84.128.1 to 73.84.255.25473.84.255.25532,766
17173.85.0.0/1773.85.0.1 to 73.85.127.25473.85.127.25532,766
17273.85.128.0/1773.85.128.1 to 73.85.255.25473.85.255.25532,766
17373.86.0.0/1773.86.0.1 to 73.86.127.25473.86.127.25532,766
17473.86.128.0/1773.86.128.1 to 73.86.255.25473.86.255.25532,766
17573.87.0.0/1773.87.0.1 to 73.87.127.25473.87.127.25532,766
17673.87.128.0/1773.87.128.1 to 73.87.255.25473.87.255.25532,766
17773.88.0.0/1773.88.0.1 to 73.88.127.25473.88.127.25532,766
17873.88.128.0/1773.88.128.1 to 73.88.255.25473.88.255.25532,766
17973.89.0.0/1773.89.0.1 to 73.89.127.25473.89.127.25532,766
18073.89.128.0/1773.89.128.1 to 73.89.255.25473.89.255.25532,766
18173.90.0.0/1773.90.0.1 to 73.90.127.25473.90.127.25532,766
18273.90.128.0/1773.90.128.1 to 73.90.255.25473.90.255.25532,766
18373.91.0.0/1773.91.0.1 to 73.91.127.25473.91.127.25532,766
18473.91.128.0/1773.91.128.1 to 73.91.255.25473.91.255.25532,766
18573.92.0.0/1773.92.0.1 to 73.92.127.25473.92.127.25532,766
18673.92.128.0/1773.92.128.1 to 73.92.255.25473.92.255.25532,766
18773.93.0.0/1773.93.0.1 to 73.93.127.25473.93.127.25532,766
18873.93.128.0/1773.93.128.1 to 73.93.255.25473.93.255.25532,766
18973.94.0.0/1773.94.0.1 to 73.94.127.25473.94.127.25532,766
19073.94.128.0/1773.94.128.1 to 73.94.255.25473.94.255.25532,766
19173.95.0.0/1773.95.0.1 to 73.95.127.25473.95.127.25532,766
19273.95.128.0/1773.95.128.1 to 73.95.255.25473.95.255.25532,766
19373.96.0.0/1773.96.0.1 to 73.96.127.25473.96.127.25532,766
19473.96.128.0/1773.96.128.1 to 73.96.255.25473.96.255.25532,766
19573.97.0.0/1773.97.0.1 to 73.97.127.25473.97.127.25532,766
19673.97.128.0/1773.97.128.1 to 73.97.255.25473.97.255.25532,766
19773.98.0.0/1773.98.0.1 to 73.98.127.25473.98.127.25532,766
19873.98.128.0/1773.98.128.1 to 73.98.255.25473.98.255.25532,766
19973.99.0.0/1773.99.0.1 to 73.99.127.25473.99.127.25532,766
20073.99.128.0/1773.99.128.1 to 73.99.255.25473.99.255.25532,766
20173.100.0.0/1773.100.0.1 to 73.100.127.25473.100.127.25532,766
20273.100.128.0/1773.100.128.1 to 73.100.255.25473.100.255.25532,766
20373.101.0.0/1773.101.0.1 to 73.101.127.25473.101.127.25532,766
20473.101.128.0/1773.101.128.1 to 73.101.255.25473.101.255.25532,766
20573.102.0.0/1773.102.0.1 to 73.102.127.25473.102.127.25532,766
20673.102.128.0/1773.102.128.1 to 73.102.255.25473.102.255.25532,766
20773.103.0.0/1773.103.0.1 to 73.103.127.25473.103.127.25532,766
20873.103.128.0/1773.103.128.1 to 73.103.255.25473.103.255.25532,766
20973.104.0.0/1773.104.0.1 to 73.104.127.25473.104.127.25532,766
21073.104.128.0/1773.104.128.1 to 73.104.255.25473.104.255.25532,766
21173.105.0.0/1773.105.0.1 to 73.105.127.25473.105.127.25532,766
21273.105.128.0/1773.105.128.1 to 73.105.255.25473.105.255.25532,766
21373.106.0.0/1773.106.0.1 to 73.106.127.25473.106.127.25532,766
21473.106.128.0/1773.106.128.1 to 73.106.255.25473.106.255.25532,766
21573.107.0.0/1773.107.0.1 to 73.107.127.25473.107.127.25532,766
21673.107.128.0/1773.107.128.1 to 73.107.255.25473.107.255.25532,766
21773.108.0.0/1773.108.0.1 to 73.108.127.25473.108.127.25532,766
21873.108.128.0/1773.108.128.1 to 73.108.255.25473.108.255.25532,766
21973.109.0.0/1773.109.0.1 to 73.109.127.25473.109.127.25532,766
22073.109.128.0/1773.109.128.1 to 73.109.255.25473.109.255.25532,766
22173.110.0.0/1773.110.0.1 to 73.110.127.25473.110.127.25532,766
22273.110.128.0/1773.110.128.1 to 73.110.255.25473.110.255.25532,766
22373.111.0.0/1773.111.0.1 to 73.111.127.25473.111.127.25532,766
22473.111.128.0/1773.111.128.1 to 73.111.255.25473.111.255.25532,766
22573.112.0.0/1773.112.0.1 to 73.112.127.25473.112.127.25532,766
22673.112.128.0/1773.112.128.1 to 73.112.255.25473.112.255.25532,766
22773.113.0.0/1773.113.0.1 to 73.113.127.25473.113.127.25532,766
22873.113.128.0/1773.113.128.1 to 73.113.255.25473.113.255.25532,766
22973.114.0.0/1773.114.0.1 to 73.114.127.25473.114.127.25532,766
23073.114.128.0/1773.114.128.1 to 73.114.255.25473.114.255.25532,766
23173.115.0.0/1773.115.0.1 to 73.115.127.25473.115.127.25532,766
23273.115.128.0/1773.115.128.1 to 73.115.255.25473.115.255.25532,766
23373.116.0.0/1773.116.0.1 to 73.116.127.25473.116.127.25532,766
23473.116.128.0/1773.116.128.1 to 73.116.255.25473.116.255.25532,766
23573.117.0.0/1773.117.0.1 to 73.117.127.25473.117.127.25532,766
23673.117.128.0/1773.117.128.1 to 73.117.255.25473.117.255.25532,766
23773.118.0.0/1773.118.0.1 to 73.118.127.25473.118.127.25532,766
23873.118.128.0/1773.118.128.1 to 73.118.255.25473.118.255.25532,766
23973.119.0.0/1773.119.0.1 to 73.119.127.25473.119.127.25532,766
24073.119.128.0/1773.119.128.1 to 73.119.255.25473.119.255.25532,766
24173.120.0.0/1773.120.0.1 to 73.120.127.25473.120.127.25532,766
24273.120.128.0/1773.120.128.1 to 73.120.255.25473.120.255.25532,766
24373.121.0.0/1773.121.0.1 to 73.121.127.25473.121.127.25532,766
24473.121.128.0/1773.121.128.1 to 73.121.255.25473.121.255.25532,766
24573.122.0.0/1773.122.0.1 to 73.122.127.25473.122.127.25532,766
24673.122.128.0/1773.122.128.1 to 73.122.255.25473.122.255.25532,766
24773.123.0.0/1773.123.0.1 to 73.123.127.25473.123.127.25532,766
24873.123.128.0/1773.123.128.1 to 73.123.255.25473.123.255.25532,766
24973.124.0.0/1773.124.0.1 to 73.124.127.25473.124.127.25532,766
25073.124.128.0/1773.124.128.1 to 73.124.255.25473.124.255.25532,766
25173.125.0.0/1773.125.0.1 to 73.125.127.25473.125.127.25532,766
25273.125.128.0/1773.125.128.1 to 73.125.255.25473.125.255.25532,766
25373.126.0.0/1773.126.0.1 to 73.126.127.25473.126.127.25532,766
25473.126.128.0/1773.126.128.1 to 73.126.255.25473.126.255.25532,766
25573.127.0.0/1773.127.0.1 to 73.127.127.25473.127.127.25532,766
25673.127.128.0/1773.127.128.1 to 73.127.255.25473.127.255.25532,766

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.