IPv4 CIDR calculator
Enter an IPv4 address with a prefix like 192.168.1.42/24 to get the network, broadcast, netmask and usable host range.
- Runs in your browser
- No upload
- Result stays on your device
Privacy & limitsRuns in your browser. Nothing is uploaded.
Input content stays in this tab; Refentra does not upload or store it. Optional aggregate action counts are sent only with your usage consent. Clear the workspace when finished.
Supported profile: IPv4 /0–/32 only; /31 point-to-point, /32 single host; no scanning or IPv6.
Maximum text: 200,000 UTF-16 units; parser limits can be smaller. Worker time limit: 15 seconds (regex 1.5 seconds).
Check the input and the result
- Prepare and choose the operation
Enter an IPv4 address with its prefix length, and keep the host address you supplied apart from the computed network address.
- Check a concrete example
Use this sample and compare the indicated result: 192.168.1.42/24 → network=192.168.1.0/24; broadcast=192.168.1.255; 192.168.1.1–192.168.1.254; usableHosts=254
- Check the output before you reuse it
Review the network, mask, broadcast and usable range. /31 and /32 follow the point-to-point and single-host conventions instead of subtracting two.
Answers for this task
Does the host range prove addresses are available?
No. It is subnet arithmetic only. DHCP leases, routing, reservations and the devices that can actually be reached are not queried.
What should I check if the input fails?
Use four integer octets from 0–255 and a prefix of 0–32. IPv6, hostnames and partial IPv4 shorthand are not accepted in this input format.
Where does this tool stop?
IPv4 calculations run locally. They don't scan networks, assign addresses or validate your provider’s routing policy.