Subnet Calculator
IPv4 CIDR subnet calc: network, broadcast, mask, hosts.
A free IPv4 subnet calculator: enter an address with a CIDR prefix (e.g. 192.168.1.10/24) to get the network address, broadcast address, subnet mask, wildcard mask, usable host range and host count. It computes locally with 32-bit integer math.
How to use
- Enter an IPv4 address with a prefix, e.g. 10.0.0.5/22.
- Read the network, broadcast, mask, wildcard, host range and count.
- Change the prefix to recompute live.
FAQ
- What does the CIDR prefix (/24) mean?
- The prefix is the number of leading 1-bits in the subnet mask. /24 means the first 24 bits are the network part (mask 255.255.255.0), leaving 8 bits for hosts.
- Why are there two fewer usable hosts than total addresses?
- In each subnet the first address is the network and the last is the broadcast, normally not assigned to hosts, so usable = 2^(32−prefix) − 2. Exceptions: /31 makes both addresses usable (RFC 3021), and /32 is a single address.
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