Percentage Change Calculator

When you need percentage change for percentage, Percentage Change Calculator turns the relevant values into a clear answer. Enter Original Value and New Value, and the calculator uses those values to show percentage change. It helps with percentage when percentages, ratios, grades, statistics or geometry would otherwise require several manual steps. A value used as a denominator cannot be zero, so check the original, total or reference value if the calculator rejects the entry. If you are comparing alternatives, change only the value you want to test so you can see what actually changes the percentage change.

How to use Percentage Change Calculator

To use Percentage Change Calculator, start with the values that apply to your percentage case. Enter the value for Original Value, then enter the value for New Value. Run the calculation to see percentage change, then compare the answer with the values you entered before using it. Make sure the reference or total value used for division is greater than zero. For a second scenario, keep the same units and assumptions and change only the inputs that genuinely differ. Keep any cost, delay, allowance or adjustment that is not represented by a field separate unless the page specifically tells you to include it.

Why use this tool?

Percentage Change Calculator gives percentage a focused calculation so you can check the arithmetic without losing sight of the method. It is useful for working through examples, checking an answer or comparing different values using the same mathematical rule. The calculator is most helpful when you use the result alongside the method shown on the page. Because the calculation is based on Original Value and New Value, you can see which values need to change when you want to test another case. Because Percentage Change Calculator focuses only on percentage, you can change one input at a time and see how that affects percentage change without changing the basis of the comparison.

How the calculation works

Percentage Change Calculator subtracts original from new, divides by original and multiplies by 100. The formula combines Original Value and New Value directly, with each value playing a specific part in the arithmetic. Because division by zero is undefined, the calculator will not produce a numerical answer when the denominator is zero. The result gives percentage change from the stated mathematical rule, making it useful for checking your own working or comparing examples. For a second percentage case, use the same units and counting convention so the two results remain directly comparable. The worked example on the Percentage Change Calculator page provides a practical check of the same method before you enter your own values.

Example

For example, enter Original Value = 100 and New Value = 120. Using those inputs gives 20% for percentage change. This works by subtracting original from new, divide by original and multiply by 100, which gives the displayed percentage change.

Practical tip

For Percentage Change Calculator, use the real values for Original Value and New Value rather than rounded guesses when a small input change could affect the answer. Keep the same units and assumptions whenever you compare two results from this tool. Use the worked example in Percentage Change Calculator to check the method, then enter your own values without changing the mathematical rule. For a second percentage case, keep the same units and conventions and change only the values that genuinely differ.