IP Subnet Calculator

Find the network, broadcast, host range, and masks for an IPv4 address and CIDR prefix

About this calculator

The IP Subnet Calculator takes an IPv4 address and a CIDR prefix length (or a dotted subnet mask) and returns the network address, broadcast address, first and last usable host, the number of usable hosts and total addresses, the subnet and wildcard masks, the address in binary, its historic class, and whether it is private, public, or another special-purpose range. It uses exact 32-bit arithmetic: network = IP AND mask, broadcast = network OR NOT mask, and usable hosts = 2^(32 − prefix) − 2, with /31 point-to-point links counted as 2 usable hosts (RFC 3021) and /32 as a single host. Non-contiguous masks and octets above 255 are rejected.

How to use the IP Subnet Calculator tool

  1. Enter or paste your input into the field.
  2. Read the output — it updates instantly as you type.
  3. Adjust the options, if any, to fit your use case.
  4. Copy the page URL to share the exact result.

Common examples

  • 192.168.1.130/26 → network 192.168.1.128, broadcast 192.168.1.191, hosts .129–.190 (62 usable), mask 255.255.255.192, wildcard 0.0.0.63
  • 172.20.37.200/20 → mask 255.255.240.0, network 172.20.32.0, broadcast 172.20.47.255, 4,094 usable hosts
  • 10.0.0.0/8 → broadcast 10.255.255.255, 16,777,214 usable hosts, private (RFC 1918)
  • 10.1.1.0/31 → a point-to-point link with 2 usable hosts, 10.1.1.0 and 10.1.1.1

Frequently asked questions

How does the IP Subnet Calculator tool work?

Enter or paste your input and the tool processes it directly in your browser, showing the result immediately. Nothing you type is uploaded to a server — the entire computation happens on your device.

When would I use the IP Subnet Calculator tool?

It is handy for development, debugging, design and administration tasks — whenever you need this transformation or check done quickly without installing anything or trusting a third-party service with your data.

How reliable are the results?

The tool implements the relevant standard or specification directly, so its output matches what compliant software produces. Edge cases such as empty or malformed input are reported clearly instead of failing silently.

Can I share a specific result with someone else?

Yes. Your input updates the URL, so copying the address bar and sharing the link reopens the tool in the same state for whoever clicks it.