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Percentage Calculator

Runs in your browser

Six percentage calculations in one place, each showing the arithmetic so you can check the answer.

Calculators

What is X% of Y?

Enter two numbers

Fill in both fields above and the answer appears here, along with the arithmetic behind it.

Your data never leaves your device

This tool runs entirely in your browser. Nothing you enter is uploaded, stored or logged by BeeTools.

How to use the percentage calculator

  1. Choose the question you are asking

    Pick one of the six tabs. This is the step that matters most — most percentage errors are the right arithmetic applied to the wrong question.

  2. Enter your two numbers

    The field labels change with the mode so you always know which number goes where. Negative values and decimals are fine.

  3. Read the answer and check the working

    The result appears immediately, with the formula underneath and a supporting note — such as what the remainder is, or the absolute size of the change.

  4. Copy the result if you need it

    Copy places the formatted answer on your clipboard.

Features

  • Six calculations, one page

    X% of Y, X is what % of Y, increase, decrease, change and difference — no mode hunting.

  • Shows the working

    Every answer includes the formula, so you can verify the question was interpreted correctly.

  • Change vs difference

    Handles both measures properly, and explains which one you are looking at.

  • Answers as you type

    No calculate button. Results update immediately when both fields have numbers.

  • Tolerant input

    Commas, spaces and stray percent signs are accepted, so pasting from a spreadsheet works.

  • Handles the edge cases

    Division by zero and undefined change from zero are reported clearly rather than shown as Infinity.

About this tool

Percentage questions are ambiguous in ordinary English, which is why they are so easy to get wrong. "20% off 50" and "20 is what percent of 50" and "50 increased by 20%" are three different sums, and the phrase "a 20% difference" could reasonably mean either of two more. This calculator separates them into six explicit modes so you pick the question first and get the right answer second.

Every result comes with the working written out. That is not decoration — it is how you confirm the tool understood the question the way you meant it. If the formula shown is not the one you had in mind, switch modes.

Two distinctions are worth knowing. Percentage change is directional and measured against the starting value, which is why 100 → 150 is +50% but 150 → 100 is −33.3%; it is the measure meant by "sales grew 20%". Percentage difference is symmetric and measured against the average of the two values, which makes it the right choice when neither number is a baseline — comparing two independent measurements of the same thing, for example.

  • Six calculations, one page. X% of Y, X is what % of Y, increase, decrease, change and difference — no mode hunting.
  • Shows the working. Every answer includes the formula, so you can verify the question was interpreted correctly.
  • Change vs difference. Handles both measures properly, and explains which one you are looking at.
  • Answers as you type. No calculate button. Results update immediately when both fields have numbers.
  • Tolerant input. Commas, spaces and stray percent signs are accepted, so pasting from a spreadsheet works.
  • Handles the edge cases. Division by zero and undefined change from zero are reported clearly rather than shown as Infinity.

Frequently asked questions

How do I calculate a percentage of a number?

Divide the percentage by 100 and multiply by the number. For 15% of 240: 15 ÷ 100 = 0.15, and 0.15 × 240 = 36. Use the "X% of Y" mode, which also tells you what the remaining 85% comes to.

What is the difference between percentage change and percentage difference?

Percentage change is directional and relative to the starting value: from 100 to 150 is a +50% change, while from 150 to 100 is a −33.3% change. Percentage difference is symmetric and relative to the average of the two values, so 100 and 150 differ by 40% whichever order you give them. Use change for something that moved over time, and difference for comparing two independent values.

Why is a 20% increase followed by a 20% decrease not back where I started?

Because each percentage applies to a different base. 100 increased by 20% is 120; 20% of 120 is 24, so decreasing gives 96, not 100. To reverse a 20% increase you need a decrease of 16.67%. This trips people up constantly with discounts and tax calculations.

How do I work out a discount?

Use the "Decrease by %" mode: enter the original price and the discount percentage, and you get the sale price plus the amount saved. To go the other way — you know the original and the sale price and want the discount percentage — use "Percentage change", which will show it as a negative change.

Why does percentage change from zero show a dash?

Because it is genuinely undefined, not because the tool failed. Percentage change divides by the starting value, and any increase from zero is infinitely large in relative terms. When your baseline is zero, report the absolute change instead — "went from 0 to 50" is meaningful where "increased by ∞%" is not.

Can I use negative numbers?

Yes. All six modes handle negative values, and percentage change divides by the absolute value of the starting number so that a move from −100 to −50 reads as a 50% increase, which is the intuitive answer.

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