IP Address & Wildcard Mask Converter

An IPv4 address (RFC 791) is a 32-bit number. Dotted decimal writes its four bytes from the most significant down, so 192.168.1.10 is 192 × 2²⁴ + 168 × 2¹⁶ + 1 × 2⁸ + 10 = 3,232,235,786, or 0xc0a8010a in hex. The page accepts any of those forms — dotted decimal, a plain integer, 0x-prefixed hex or dotted binary — and shows the others, which is what you need when a log stores integers, a script wants hex or a course asks for the binary.

A CIDR prefix /n (RFC 4632) means the top n bits are network bits. The subnet mask is n ones followed by zeros — /26 is 255.255.255.192 — and the wildcard mask used in access lists and OSPF statements is its bitwise inverse, 0.0.0.63: a one marks a bit that may vary. Enter whichever you have and the other two are derived; a dotted value that is not a run of ones (or of zeros) is refused. Network = address AND mask, broadcast = network OR wildcard, and usable hosts are 2^(32 − n) − 2, except /31 point-to-point links (RFC 3021) and /32 host routes where every address is usable.

It does not look anything up — no WHOIS, geolocation or DNS — and it handles IPv4 only. For splitting a block into subnets use the Subnet Calculator. The two all-ones and all-zeros dotted values are read as masks (/32 and /0), not wildcards. Nothing leaves the browser; the same four anonymous usage counts as the rest of the site apply.