Subnet Calculator

Works with IPv4 and IPv6. Type an address with a prefix or mask. Everything is calculated in your browser.

IPv4
Network preset
/24

Accepted: 10.0.0.5/22, 10.0.0.5 255.255.252.0, 10.0.0.5 0.0.3.255 (wildcard), 2001:db8::1/48

Details

Split into subnets

VLSM planner

Carves into subnets sized to host counts, largest first

IPv4 prefix reference