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Percent Change Calculator

Use this percent change calculator to compare an old value with a new value and see the percentage increase or decrease.

Method and assumptions documentedFree toolAssumptions visible

Live calculator

Percent change

Percent change25.00% increase

Compares the new value with the original value.

Difference20

New value minus original value.

Multiplier1.25x

New value divided by original value.

Use this as a transparent math check. Percent, average, and fraction results can change if the denominator, original value, count, or rounding choice changes.

Which percentage tool should I use?Use the simpler calculator unless you are comparing an old and new value.
Percentage calculatorUse for percent of a number, part of a whole, or a direct percentage question.Percent change (this tool)Use when you are comparing an original value with a newer value.

Quick answer

Percent Change Calculator: what it calculates

Percent Change Calculator calculates percent change from original value and new value. The visible formula is Percent change = ((new value - original value) / original value) x 100.

ResultPercent change
InputsOriginal value, New value
FormulaPercent change formula

Formula

Percent change formula

Percent change = ((new value - original value) / original value) x 100

A positive result is an increase. A negative result is a decrease.

How to use

Steps

  1. Enter the original value.
  2. Enter the new value.
  3. Read the percentage increase or decrease.
  4. Use the difference and multiplier to double-check the size of the change.

Example

Sample calculation

Original value80
New value100
Percent change25% increase

Calculator use

Best for

  • Use this percent change calculator to compare an old value with a new value and see the percentage increase or decrease.
  • Checking everyday percent, change, average, median, fraction, and decimal math before copying a result into another task.
  • Teaching, homework, shopping, reporting, budgeting, or spreadsheet checks where the formula matters as much as the number.
  • Comparing values only after confirming the denominator, original value, count, or operation matches the question.

Before relying on it

Check first

  • Using the wrong denominator, original value, count, or operation for the math question being asked.
  • Rounding the result early and then reusing that rounded value in a second calculation.
  • Comparing an average, percentage, or fraction without checking whether outliers, zero values, or missing entries change the meaning.

Details

What to know before using the result

Scenario inputsoriginal value and new value

Keep original value and new value aligned to the same scenario so percent change represents a consistent calculation.

Method checkPercent change formula

The tool applies Percent change = ((new value - original value) / original value) x 100 to the entered values, then keeps percent change, examples, assumptions, and limits visible for review.

Benchmarks

How to read the result

Under 5%: Small move.

Often normal variation for prices, metrics, and budgets.

5% - 20%: Noticeable.

Large enough to matter for most everyday comparisons.

20%+: Large move.

Usually worth checking the inputs and the reason for the change.

Calculator accuracy

Methodology and assumptions

Formula

Percent change = ((new value - original value) / original value) x 100

Inputs used

Original value, New value

Limitations

Core math pages show standard formulas, but interpretation still depends on choosing the right denominator, operation, comparison period, and rounding point.

Review record

Catalog QA baseline on June 6, 2026. This date marks the catalog-wide automated and editorial QA baseline, not a tool-specific expert review.

Cite this page

Toolkit Shelf. Percent Change Calculator. https://toolkitshelf.com/tools/percent-change-calculator

FAQ

Common questions

How do I calculate percent change?

Subtract the original value from the new value, divide by the original value, then multiply by 100.

Is percent change the same as percent difference?

No. Percent change compares a new value against an original value. Percent difference compares two values against their average.

What does a negative percent change mean?

A negative percent change means the new value is lower than the original value.

Why does the original value matter?

Percent change divides by the original value, so using the new value as the denominator gives a different and usually misleading result.

What if the original value is zero?

Percent change from zero is not defined in the usual formula because the calculation would divide by zero.