Percentage Calculator

Calculate percentages, increases and decreases

Mode

Result

30.00

How it works

Percentage Calculator — Calculate percentages, increases and decreases. All processing happens in your browser — no upload, no signup, no email required. Free forever.

Last updated: 2026-05-06

Editor's note

We got tired of mistyping percentage change in pricing meetings. Somebody would say "the price went from 80 to 100, that's a 20% increase" and someone else would push back "no it's 25%" and both were right depending on which number you put on the bottom of the fraction. Smart people trip on (old − new) vs (new − old) every single week. We wanted a screen where the formula is visible in the UI, not a thing you have to hold in your head while a client is on the phone.

So we split it into three modes named after the question you're actually asking, not the math behind it. "X% of Y", "X is what % of Y", "% change from X to Y". The wording matters more than the equation — once you read the mode out loud, your two inputs go in the right slots. VAT and discount math are just mode one plus a sum. We resisted adding a fourth mode for tax-inclusive prices on purpose; one less button beats one more confusion.

About Percentage Calculator

Percentages are everywhere — VAT lines, tip jars, sale stickers, mortgage spreadsheets, exam scores, performance reviews — and yet most of us reach for a phone calculator and start typing a chain of multiplications and divisions, hoping the parentheses land right. The percentage calculator removes the math entirely. Pick which kind of percentage question you are answering, type the two numbers, and read the result. There are no formulas to remember and no order-of-operations traps.

Three modes cover the questions that make up the vast majority of real-world percentage work. 'X% of Y' answers "what is the discount?" — for example 20% of 150 is 30, so a $150 jacket marked 20% off saves you $30. 'X is what % of Y' answers "what proportion?" — 30 out of 60 is 50%, useful for grading, conversion rates, or progress bars. '% change from X to Y' answers "how much did it grow or shrink?" — going from 100 to 120 is +20%, from 100 to 80 is −20%. Behind the scenes the formulas are (X/100)·Y, (X/Y)·100, and ((Y−X)/X)·100.

A fourth common question — "add 18% VAT to 100" — is just X% of Y plus the original: 100 + (18/100)·100 = 118. Use mode one to compute the tax part and add it to the base. Likewise, removing tax from a gross price is mode two in disguise: 118 is what % of 100 returns 118%, so the tax fraction is 18%.

How to use Percentage Calculator

Pick the Mode that matches your question: X% of Y, X is what % of Y, or % change from X to Y.
Type the first number into the X field.
Type the second number into the Y field.
Read the Result instantly — it updates as you type.
Switch modes at any time without retyping; X and Y stay populated so you can ask several questions about the same pair of numbers.

Common use cases

Calculating a restaurant tip — 18% of a $74 bill is $13.32.
Working out a sale price — a $250 coat at 30% off costs $250 − (30% of 250) = $175.
Tracking month-over-month growth — revenue from $42,000 to $48,300 is a +15% change.
Verifying a statistics homework answer like "45 is what % of 180" → 25%.
Pricing your hourly rate after a 12% raise — multiply your old rate by mode one with X = 112.

Tips & common mistakes

Percentage change uses the OLD value as the denominator. A drop from 200 to 100 is −50%, but a recovery from 100 back to 200 is +100% — the percentages are not symmetric.
If your second input is zero in mode two or three, the answer is mathematically undefined and the result will display NaN. Adjust to a non-zero divisor.
A discount stack does not add: 20% off then 10% off is not 30% off. It is 0.8 × 0.9 = 0.72, i.e. 28% off the original.
Negative numbers are accepted — useful for cost reductions or temperature drops — but check the sign of the result to make sure the framing matches your question.

Frequently asked questions

Which percentage formulas are available?

Three: 'X% of Y' (e.g. 20% of 150), 'X is what % of Y' (e.g. 30 is what % of 60), and '% change from X to Y' (positive for increase, negative for decrease).

How is percentage change calculated?

It's ((new − old) / old) × 100. So going from 100 to 120 is +20%, and from 100 to 80 is −20%.

Why does my result show NaN?

It usually means a divisor is zero (you can't compute X / 0). Adjust the second input to a non-zero number.

How do I add tax or VAT to a price?

Use mode one to compute the tax: e.g. 18% of 250 = 45. Then add it back: 250 + 45 = 295. Some people prefer the shortcut 250 × 1.18 = 295, which is mathematically identical.

What is the difference between percentage points and percent change?

If unemployment moves from 5% to 7%, that is a 2 percentage-point increase but a 40% relative increase ((7−5)/5×100). Mode three computes the relative change; subtraction gives the point change.

Can I chain calculations, like apply two successive discounts?

Run mode one twice. After the first discount, copy the result into X for the next round. The combined discount is always less than the simple sum because the second percentage applies to a smaller base.

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