Percentage Calculator

Use this percentage calculator to compare values and changes quickly

This Percentage Calculator helps you answer three common questions: what is a percentage of a number, what percent one value is of another, and how much a value has increased or decreased in percentage terms.

Choose the type of calculation you need at the top of the calculator box. Enter your numbers and the result will update automatically. You can also use the Calculate button if you prefer.

This tool is useful for checking discounts, test scores, personal goals, financial changes, and any quick comparison between two values where you want the percentage or percentage change.

Assumptions and how to use this calculator

• All values are treated as plain numbers with optional commas.
• Percentages are entered as simple numbers, not decimals. For example, type 15 for 15%, not 0.15.
• For the “X is what percent of Y” mode, the second value (Y) must be non-zero.
• For the percent change mode, the calculator uses: ((new value − original value) / original value) × 100.
• Results are rounded to two decimal places for readability.

Common questions

How do I work out a percentage of a number?

Select “What is X% of Y?”, enter the percentage in the first box and the base number in the second box. The result shows the value that represents that percentage of the base number.

How do I find what percent one number is of another?

Choose “X is what percent of Y?”, put the part or smaller number in the first field and the whole or comparison number in the second field. The calculator returns the percentage that the first value represents of the second value.

How is percent change calculated?

In “Percent change from X to Y” mode, the first value is treated as the starting point and the second as the new value. The calculator applies ((new − original) / original) × 100.

Can this calculator handle negative numbers?

Yes. Negative values are allowed in all modes, but you should ensure negative inputs make sense for your situation.

When should I use percent change instead of a simple percentage?

Use percent change for “before vs after” comparisons like prices or performance. Use the other modes for one-off comparisons.