Subnet calculator

Work out the range, broadcast and host count of an IPv4 or IPv6 network.

Processed on your device, never uploaded

Network

Address and prefix

IPv4 or IPv6, as CIDR (/24) or with a netmask (255.255.255.0)

Result

The network, range and host count appear here.

What it does

The subnet calculator takes an address with a prefix, such as 192.168.1.0/24 or 2001:db8::/48, and shows the network address, netmask, wildcard, broadcast, first and last host and how many hosts fit. It also splits the network into smaller subnets and lists them. A netmask like 255.255.255.0 works too.

How to use it

1Enter an address with a prefix, like 10.0.0.0/16.
2Read the network, range and host count.
3Choose a longer prefix to split it into subnets, and copy the list.

Questions

Does it do IPv6?

Yes, with the same table and a split list. Counts are shown in full, even for a /48.

Why are there two fewer hosts than addresses?

In IPv4 the first address is the network and the last is the broadcast. A /31 and a /32 are special cases and use all addresses.

Is anything sent?

No. It is plain arithmetic in your browser.