Free browser tool

Percentage Change Calculator

Calculate a percentage increase or decrease from an original value to a new value.

Old valueNew value

Difference

Percentage change

Increase and decrease use the original value

The calculation divides the signed difference by the absolute original value. Percentage change is undefined when the original value is zero.

Worked example and guidance

Use Percentage Change Calculator with a checkable example

Example input

Old value 80; new value 100

Expected output

+25%

For the example above, the output should be read as a calculation under the input and branch conventions shown by the tool. Percentage Change Calculator performs the browser-side transformation or calculation, but the mathematical convention, units, domain, and intended publishing format still come from your problem.

How to use it

Enter or paste a small known number or algebraic expression before using a larger real-world example.
Choose the required options and run Percentage Change Calculator; keep the original input available for comparison.
Read the result together with its domain restrictions, substituted values, and independent recomputation, then copy or export only after the check passes.

Useful for

Checking a worked example
Exploring how inputs change a result
Preparing a clean result for a technical note

Limits and checks

The tool may show numeric rather than symbolic results
Extraneous or excluded solutions still require a domain check
Browser floating-point arithmetic has finite precision

Percentage Change Calculator FAQ

Does Percentage Change Calculator upload my input?

No. The published tool runs in the browser. Avoid placing confidential material in share URLs or exported files that you later send elsewhere.

How should I verify a Percentage Change Calculator result?

Start with the worked example, inspect the domain restrictions, substituted values, and independent recomputation, and compare one result with an independent calculation or representation.

What should I do when the input is rejected?

Reduce the input to the smallest failing number or algebraic expression, check delimiters and supported syntax, then add the remaining structure back one step at a time.

Next steps

Continue after Percentage Change Calculator

Your inputs stay in this browser. Use a related guide or reference to verify the result and reuse it correctly.

How to Calculate Percentage ChangeCalculate percentage increase or decrease from an old value to a new value, with the original value as the reference denominator.Percentage Change FormulaMeasures relative increase or decrease from an original nonzero value.% Percent SignMeans per hundred.

Maintained reference

How this tool was checked

Tool documentation records what was tested, which sources define compatibility, and where the browser utility stops.

Supporting tool

Review record

Last reviewed: 2026-07-27
Method: Ran the documented small example for Percentage Change Calculator, checked the result independently, reviewed invalid-input behavior, and inspected browser-local output and copy actions.
Verified against: The displayed calculation and constraints were compared with standard definitions relevant to Percentage Change Calculator; unsupported or ambiguous inputs remain explicitly limited.
Maintainer: Chevee Math Tools

Known limits

Percentage Change Calculator supports the input forms exposed by its interface, not every symbolic or domain-specific variant.
Browser floating-point arithmetic and displayed rounding can differ from exact symbolic results.
Verify high-stakes, graded, engineering, financial, or publication results with an independent method.

Primary sources

amsmath packageCTAN — Aligned equations, matrices, cases, operators, and advanced mathematical typesetting.

See the editorial and review policy, the source hierarchy, or submit a correction.