How to use the CIDR Calculator
Use this calculator to turn a CIDR block into its network boundary, mask, address range, and usable host range without sending the address anywhere.
- Enter an IPv4 or IPv6 block in address/prefix form, such as 10.0.0.0/24.
- Check the normalized network and final address to confirm the block boundaries.
- Use the host range and address counts when planning allocations, routes, firewall rules, or overlap checks.
How to read the result
The prefix fixes the network portion of every address in the block. The first and last values define the full range; IPv4 usable-host figures normally exclude the network and broadcast addresses.
Example
- Input
10.0.0.0/24- What to look for
- The block runs from 10.0.0.0 through 10.0.0.255, with the ordinary IPv4 host range from 10.0.0.1 through 10.0.0.254.
Before you act on the result
The calculation proves address boundaries only. It cannot inspect a live route table, detect another network that overlaps the block, or show whether a firewall permits traffic.
Read the CIDR Calculator Guide for the technology overview and troubleshooting steps.