Subnet calculator

Paste a prefix. Get the network, the range you can use, and the mask without opening a spreadsheet.

Notes

• Usable hosts exclude the network and broadcast address for IPv4 prefixes shorter than /31.
• /31 returns both addresses usable (RFC 3021); /32 returns the single address.
• IPv6 output is the compressed network form and the size of the range, because counting hosts is not useful there.