Nightroll

Free Subnet & CIDR Calculator

Type an address with its prefix to see the whole subnet.

IPv4 addresses without a prefix are read as /24.

How to make a subnet calculation

  1. Type an address and prefix, like 192.168.1.10/24 or 2001:db8::/48.
  2. Read the network, mask and host range.
  3. Use the prefix buttons to compare sizes.

Frequently asked questions

Why are there 2 fewer hosts?
In IPv4 the first address names the network and the last is for broadcast. /31 and /32 are special cases with no such loss.
Is my data stored?
No. Everything happens in your browser and your inputs are saved only on this device.