Easy Converter

Percentage Calculator

Solve any percentage problem in one click: what is X% of Y, X is what % of Y, percentage increase, percentage decrease, percentage change between two values, reverse percentage. Eight scenarios covered, live-updating, mobile-friendly.

How to use

  1. 1

    Pick a scenario

    Choose the variant that matches your question (e.g. "X% of Y", "X is what % of Y").

  2. 2

    Enter known values

    Type the numbers you have. The calculator solves for the missing variable.

  3. 3

    Read the result

    The result updates live and shows the formula used.

Technical details

Percentages are simply ratios out of 100: `X%` means `X / 100`. Every percentage problem reduces to one of three operations — finding a percentage of a value, finding what percentage one value is of another, or solving for one of the variables given the percentage and another. The calculator presents all variants in a single interface.

Percentage of a value: `result = base × percent / 100`. Example: 15% of 200 = 30. This is the calculation you use for discounts, sales tax and tips.

Percentage change: `change = (new − old) / old × 100`. A negative change is a decrease; a positive one is an increase. Note that decreasing by 50% and then increasing by 50% does not return you to the original — it leaves you 25% lower (50 × 1.5 = 75, not 100).

Reverse percentage: given the discounted price and discount percent, find the original price. Formula: `original = discounted / (1 − discount/100)`. Useful for evaluating sale offers and reverse-engineering markup.

Frequently asked questions

How do I compute a discount?
Use "What is X% of Y" with the discount percent and the original price. Subtract to get the sale price.
Why is a 50% decrease followed by a 50% increase not zero?
Because the percentages apply to different bases. 100 → 50 (−50%) → 75 (+50% of 50).
Can the calculator handle negative numbers?
Yes. Percentage change can be negative, and the calculator displays the sign explicitly.
Is the result precise?
Yes, to 6 significant figures. Display is rounded to 2 decimals by default.
Does it work offline?
Yes. Once loaded, no network is needed.
Reviewed by:Easy Converter Engineering Team

This tool was tested and calibrated by our engineering team. All processing happens locally in your browser — your files and data never leave your device.