Netmask ⇄ CIDR Converter

Type a subnet mask (255.255.255.0) or a CIDR prefix (/24 or 24) — the converter shows the other form, the wildcard mask and the address count.

Both directions work: 255.255.240.0 → /20 and /20 → 255.255.240.0.

CIDR reference table

Every prefix with its mask, wildcard and address count.

CIDRNetmaskWildcardAddressesUsable hosts