Percentage Calculator

Five percentage calculators in one — all results update in real time as you type. No button to click.

① What is X% of Y?
What is % of ?
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② X is what percent of Y?
is what % of ?
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③ Percentage change from X to Y
From to
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④ X is Y% of what? (reverse)
is % of what?
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⑤ Add or remove X% from Y
Value ± %
➕ Add X%
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➖ Remove X%
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About percentages

What is a percentage?

A percentage is a way of expressing a number as a fraction of 100. The symbol % literally means "per hundred". Percentages make it easy to compare proportions regardless of the total size: whether you have 50 apples or 5 000 apples, "40% are red" is immediately meaningful.

The five essential formulas

Every percentage problem reduces to one of five formulas. This calculator covers all of them:

  • X% of Y → result = Y × X ÷ 100 — e.g. 15% of 80 = 12
  • X is what % of Y → result = (X ÷ Y) × 100 — e.g. 20 ÷ 80 × 100 = 25%
  • % change → result = ((new − old) ÷ old) × 100 — e.g. 80 → 100 = +25%
  • Reverse (X is Y% of what?) → result = X × 100 ÷ Y — e.g. 12 is 15% of 80
  • Add / remove X% → Y × (1 ± X/100) — e.g. 200 + 20% = 240

Common real-world uses

Discounts: A 30% discount on a €120 item → remove 30% from 120 → €84.
VAT / sales tax: Add 20% VAT to €200 → 200 + 20% = €240.
Salary raise: €35 000 with a 5% raise → 35 000 + 5% = €36 750.
Grade: 68 correct answers out of 80 → 68 is what % of 80? = 85%.
Stock change: Share from $50 to $63 → % change = +26%.

Percentage vs percentage points

A common source of confusion: if an interest rate rises from 3% to 5%, it has increased by 2 percentage points — but by 66.7% in relative terms ((5−3)/3 × 100). News articles often mix these up. The percentage-change calculator above always gives the relative change.

Frequently asked questions

A percentage is a number expressed as a fraction of 100. The symbol % means "per hundred". For example, 25% means 25 out of 100, or 0.25 as a decimal.
Multiply the number by the percentage, then divide by 100. Formula: result = Y × X ÷ 100. Example: 15% of 80 = 80 × 15 ÷ 100 = 12.
Divide X by Y, then multiply by 100. Formula: (X ÷ Y) × 100. Example: 20 is what % of 80? (20 ÷ 80) × 100 = 25%.
Formula: ((new value − old value) ÷ old value) × 100. A positive result is an increase; a negative result is a decrease. Example: from 80 to 100 → ((100−80)÷80)×100 = +25%.
If X is Y% of some number, the original = X × 100 ÷ Y. Example: 12 is 15% of what? 12 × 100 ÷ 15 = 80.
To add X% to Y: Y × (1 + X/100). To subtract X% from Y: Y × (1 − X/100). Example: 200 + 20% = 240. 240 − 20% = 192. Note: adding then removing the same percentage does not return to the original.
A percentage point is an absolute difference between two percentages. If a rate rises from 3% to 5%, that is a 2 percentage-point increase, but a 66.7% relative increase. The percentage-change calculator gives the relative change.
Use calculator ⑤ (remove X% from Y). Enter the original price as Y and the discount rate as X%. Example: 30% off €120 → 120 − 30% = €84.

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