CIDR Subnet Calculator
Calculate network, subnet mask, broadcast, first/last usable addresses, and address counts from IPv4/CIDR input.
How to use
- Enter an IPv4/CIDR such as 192.168.1.0/24 and calculate.
Capabilities and scope
The dedicated runner validates octets 0–255 and prefix 0–32, then uses 32-bit bitmask operations.
How it works
IPv4 is converted to uint32, masked to network/broadcast, with host endpoints excluded for prefixes up to /30 and special handling for /31 and /32.
Example
192.168.1.10/24 reports network 192.168.1.0 and broadcast 192.168.1.255.
Useful for
- Inspect IPv4 subnet ranges and usable-address counts
Before you use it
- IPv6 CIDR is unsupported and operational address-reservation policies can differ by environment.
Standards and references
Frequently asked questions
Does /31 show zero usable addresses?
No. The current runner treats /31 as two usable addresses and /32 as one.