Percentage Calculator

Five percentage calculations in one place: percent of a number, what percent X is of Y, add a percent, subtract a percent, and percent change.

What is X% of Y?

% of

X is what % of Y?

of

Y plus X%

+ X%

Y minus X%

− X%

Percent change from A to B

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About the Percentage Calculator

A percentage is a way of expressing a number as a fraction of 100, which makes proportions instantly comparable: 37 out of 50 is harder to feel than 74%. Percentages appear every time you face a discount, a tax slab, an exam score, an interest rate, or a growth figure — and each of those situations asks a slightly different question.

This tool bundles the five questions people actually ask: What is X% of Y? What percent is X of Y? What do you get adding X% to Y? What remains after subtracting X%? And by what percent did A change into B? Each is a separate card; each computes as you submit.

Percent-change deserves special care because it is directional: moving from 100 to 150 is a 50% increase, but moving from 150 back to 100 is only a 33.33% decrease. The base changes, and this tool does that bookkeeping correctly using the absolute value of the starting point.

How to use the Percentage Calculator

  1. 1 Pick the card matching your question — percent of a number, percent of a total, add or subtract a percent, or percent change.
  2. 2 Fill the two inputs in that card; labels make which number goes where unambiguous.
  3. 3 Press Calculate — the answer appears under the card, formatted to a practical number of decimals.
  4. 4 Cross-check unusual results by re-entering the numbers in a different card (for example, verify a 20% discount with the subtract-percent card).

Key features

Five calculators in one

Every common percentage question covered without formula memorisation.

Directional percent change

Increase and decrease are computed against the correct base, with the direction named in the answer.

Zero-division guards

Helpful messages instead of Infinity when a base is zero.

Instant feedback

All computation is local and immediate — nothing is uploaded anywhere.

Who uses the Percentage Calculator?

  • Shoppers verifying discount claims and GST-inclusive prices.
  • Students checking exam percentages and aggregate scores.
  • Employees computing salary hikes (a 10% raise on 50,000 is 55,000).
  • Business owners comparing margins, GST rates, and YoY growth.
  • Fitness and finance tracking — body-fat changes, portfolio moves, savings rates.

Tips and best practices

  • Percent change of a quantity that can pass through zero (like profit) is undefined — use absolute difference or a different metric.
  • A 50% loss needs a 100% gain to recover; percentage moves are not symmetric, which is why drawdowns hurt so much.
  • When stacking changes (a 10% rise then a 10% fall), multiply factors (1.10 × 0.90 = 0.99) — you end 1% lower, not flat.
  • Percentage points are not percentages: an interest rise from 8% to 9% is one percentage point, or a 12.5% increase.
  • For marks, confirm whether the board reports best-of-subjects or all subjects — the denominators differ.

Frequently asked questions

Multiply the number by the percentage and divide by 100: 20% of 150 is 150 × 20 ÷ 100 = 30.

Divide the part by the whole and multiply by 100: 45 out of 60 is 45 ÷ 60 × 100 = 75%.

(New − old) ÷ |old| × 100. Positive results are increases, negative results decreases. The absolute value keeps the base correct when the starting number is negative.

The change is relative to the starting value: 100 → 150 is +50%, but 150 → 100 is −33.33%. Same absolute gap, different base.

A percentage point is the arithmetic gap between two percentages (8% to 9% = +1 point), while a percentage is relative (9% is 12.5% more than 8%).