IP Subnet Calculator

IPv4 and IPv6 CIDR calculator: network, mask, host range, subnet splitting and membership checks

Split into subnets

New prefix length /

Calculate a network, then split it.

Is this address in the network?

About this tool

Enter an address with a prefix length (CIDR) — or a bare address, or an IPv4 dotted mask such as 10.0.0.1/255.255.255.0. All math uses BigInt, so IPv4 and IPv6 (including :: shorthand and embedded IPv4) share the same code path. Everything runs locally in your browser.

Network, broadcast, netmask, wildcard, first/last usable host and host counts (RFC 3021 /31 and /32 handled)
Address scope detection (private, loopback, link-local, multicast, documentation, CGNAT, ULA)
Split a network into equal smaller subnets
Test whether an address belongs to the network