IP/CIDR Subnet Calculator
Enter an IPv4 CIDR block to calculate subnet mask, network address, broadcast address, first and last host, and address counts.
Runs locally in your browser. This tool does not upload your input.
IPv4 CIDR
Initial support for IPv4.
Subnet
- Mask
- 255.255.255.0
- Network
- 192.168.1.0
- Broadcast
- 192.168.1.255
- First host
- 192.168.1.1
- Last host
- 192.168.1.254
- Addresses
- 256
- Usable hosts
- 254
How to calculate IPv4 subnets
Enter an IPv4 CIDR block to see mask, network, broadcast, host range, and address counts.
How to use it
Enter or load your data, adjust the available options, and review the generated result before copying or downloading it.
What the result includes
IP Subnet Calculator focuses on the practical output most users need first, with clear validation messages when the input cannot be processed.
Good inputs
- Use representative sample data before applying the result to production work.
- Check warnings and edge cases shown by the tool.
- Copy only the final output once it matches your expected format.
Local processing
This tool runs in your browser. The content you enter or the files you choose are not sent to a ProntoUso server.
IP Subnet Calculator FAQ
- Does this tool upload my input?
- No. It runs locally in your browser and does not send the input to a ProntoUso server.
- Can I use the result directly?
- Yes, but review it first when the output affects production code, SEO files, campaigns, or business calculations.
- What happens if the input is invalid?
- The tool shows a clear error or warning so you can fix the input before using the result.