Security

IP Range Calculator

Calculate the size of an IPv4 range between a starting IP address and an ending IP address.

Last reviewed: April 30, 2026Free toolMethodology

IP Range Calculator

These fields start with sample inputs. Keep them or replace them, then run the tool to show a fresh result.

Result

Calculating the sample result.

Why it matters

IP range math comes up in firewall rules, vendor allowlists, and migration planning where teams need to understand how broad a range really is.

When to use

  • Checking firewall rule scope
  • Comparing manually specified IP ranges
  • Estimating the size of a migration or allowlist block

Inputs & Outputs

Inputs

  • Start IP and end IP define the inclusive IPv4 range.

Outputs

  • Address count shows the total number of IPv4 addresses in the inclusive range.
  • Range summary helps verify that the start and end boundaries are in the right order.

Range-count method

The tool converts both IPv4 addresses into numeric form, subtracts the start from the end, and adds one to account for the inclusive range.

Address count = end IP - start IP + 1

Worked example

1

Allowlist review

An admin wants to know how many addresses are covered from 203.0.113.10 to 203.0.113.25.

Inputs

  • Start IP: 203.0.113.10
  • End IP: 203.0.113.25

Steps

  • Convert both IPs to integers
  • Subtract and add one for the inclusive range

Result

  • The tool returns the total address count in the range.

Edge cases & caveats

  • This tool focuses on manual IPv4 ranges rather than CIDR blocks.
  • It does not tell you whether the range is operationally safe to allowlist.

Frequently Asked Questions

Why use this instead of CIDR notation?

Because many operational tickets and third-party forms still use explicit start and end IP ranges.

Can the start IP be higher than the end IP?

No. The tool expects the lower address first so the range can be interpreted correctly.

Keep going

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