Percentage Calculator
Calculate percentages, ratios, and percentage change.
Enter both values to see your result.
This handles the three percentage questions people actually ask: what is X percent of Y, X is what percent of Y, and what is the percentage change from X to Y. They are different calculations and confusing them is the source of most percentage errors — particularly the difference between a percentage change and a percentage point difference, which are not the same thing. The formulas are (X ÷ 100) × Y, (X ÷ Y) × 100, and ((new − old) ÷ old) × 100. A rate moving from 4 percent to 6 percent has risen two percentage points but 50 percent — both statements are true and they describe the same move. The other trap is asymmetry: a 50 percent fall needs a 100 percent rise to recover, because the base has changed. Percentage change is undefined when the starting value is zero.
About the Percentage Calculator
A clean, three-in-one percentage calculator. Find a percentage of any number, work out what percentage one number is of another, or measure the percentage change between two values — with instant results as you type.
How to use the Percentage Calculator
- 01Pick the calculation mode that matches your question.
- 02Enter your two numbers into the input fields.
- 03Read the answer instantly — no "Calculate" button needed.
- 04Switch modes to run another calculation right away.
Why use our Percentage Calculator
- 01
Three modes
X% of Y, X is what % of Y, and percentage change — covers every common question.
- 02
Instant results
Answers update live as you type, with sensible decimal formatting.
- 03
Handles negatives
Percentage change works correctly for both increases and decreases.
- 04
Private & free
Everything is calculated locally in your browser — no sign-up, no tracking.
How do you calculate a percentage?
Finding a percentage of a number multiplies: X percent of Y is (X ÷ 100) × Y, so 15 percent of 80 is 12. This is the calculation behind tips, tax, commission and discounts. Expressing one number as a percentage of another divides: X is (X ÷ Y) × 100 percent of Y, so 12 out of 80 is 15 percent. This is the calculation behind test scores, completion rates and market share. Percentage change measures movement between two values: ((new − old) ÷ old) × 100, so going from 80 to 92 is a 15 percent increase. The critical detail is that the denominator is the original value, which is why the direction matters — an increase from 80 to 100 is 25 percent, but the decrease from 100 back to 80 is only 20 percent, because the base changed. That asymmetry is not a quirk to be corrected; it is what the measure means.
Percentage points versus percentages
This distinction causes real confusion in reporting and is worth stating precisely. If an interest rate rises from 4 percent to 6 percent, that is an increase of two percentage points and a 50 percent increase — both are correct descriptions of the same change, and they sound wildly different. Reporting that mixes them up, deliberately or otherwise, produces misleading impressions in both directions: 'rates up 50 percent' is technically true and alarming, while 'rates up two points' is technically true and calm. The rule is that percentage points describe the arithmetic difference between two percentages, while percentage change describes the proportional difference. Use points when both figures are already percentages — unemployment, interest rates, market share, poll numbers — and percentage change when comparing quantities. When reading a statistic, checking which one is being used is often the difference between understanding it and being misled by it.
Why successive percentages do not add
A 10 percent increase followed by a 10 percent decrease does not return you to where you started. Take 100, add 10 percent to get 110, then subtract 10 percent of 110 — which is 11, not 10 — leaving 99. The loss occurs because each percentage applies to a different base. The same effect explains why a 50 percent fall requires a 100 percent rise to recover: dropping from 100 to 50 is a halving, and getting back to 100 from 50 is a doubling. This matters practically in investment returns, where a portfolio that falls 20 percent needs a 25 percent gain to break even, and in any sequence of price changes. To combine successive percentage changes correctly, multiply the factors rather than adding the percentages: a 10 percent rise then a 5 percent fall is 1.10 × 0.95 = 1.045, a 4.5 percent net increase, not 5 percent.
Recovering from a percentage fall
| Fall | Gain needed to recover | Why |
|---|---|---|
| 10% | 11.1% | 90 → 100 is a larger proportional step |
| 20% | 25% | 80 → 100 |
| 33% | 50% | 67 → 100 |
| 50% | 100% | 50 → 100 is a doubling |
| 75% | 300% | 25 → 100 is a quadrupling |
Percentage changes are asymmetric because the base changes. Multiply factors to combine them, never add.
Frequently asked questions
How do I find X% of a number?
Multiply: (X ÷ 100) × Y. So 15% of 80 is 0.15 × 80 = 12.
How do I express one number as a percentage of another?
Divide and multiply by 100: (X ÷ Y) × 100. So 12 out of 80 is 15%.
How is percentage change calculated?
((new − old) ÷ old) × 100. The denominator is always the original value, which is why increases and decreases between the same pair differ.
Why isn't a 25% increase reversed by a 25% decrease?
Because each applies to a different base. 100 up 25% is 125; 125 down 25% is 93.75, not 100.
What is the difference between percent and percentage points?
If a rate goes from 4% to 6%, that is 2 percentage points and a 50% increase. Points describe the arithmetic gap; percentage change describes the proportional one.
How much do I need to gain back after a 50% loss?
100%. Falling from 100 to 50 is a halving; returning to 100 requires doubling.
How do I combine two percentage changes?
Multiply the factors. A 10% rise then a 5% fall is 1.10 × 0.95 = 1.045, a 4.5% net increase — not 5%.
Can a percentage be over 100?
Yes. A value can be more than the whole it is compared against — 150% of 80 is 120, and growth from 40 to 120 is a 200% increase.
Is my input stored?
No. All arithmetic runs in your browser and nothing is transmitted.
Last updated
Standard percentage arithmetic. Percentage-point terminology follows conventional statistical usage as used by national statistics offices.