The Percentage Calculator answers the three questions people search for most: what is X% of Y, X is what percent of Y, and what is the percentage increase (or decrease) from A to B. Percentages appear in tax, tips, interest, grades, sales, statistics and news headlines — this tool covers each case with the correct formula.
The three core formulas
- Part = Percent × Whole ÷ 100 — e.g. 20% of 250 = 50.
- Percent = Part ÷ Whole × 100 — e.g. 30 of 120 = 25%.
- % change = (New − Old) ÷ Old × 100 — e.g. 80 → 100 = +25%.
Worked examples
Tip on a restaurant bill
Bill 86.40, tip 18%. Tip = 86.40 × 18 ÷ 100 = 15.55. Total = 101.95.
Exam score
You got 63 out of 75. Score = 63 ÷ 75 × 100 = 84%.
Salary rise
From 52,000 to 58,240. Change = (58,240 − 52,000) ÷ 52,000 × 100 = 12%.
Where percentages are used
- Sales tax, VAT and GST added at checkout.
- Interest rates on loans, credit cards and savings accounts.
- Discounts on retail prices, coupons and Black Friday deals.
- Statistics: unemployment, election polls, market share.
- Fitness and nutrition: body-fat %, macros, RDA of nutrients.
Tips and common mistakes
- Don't confuse a 5% rise with a 5 percentage-point rise — they mean different things.
- A 50% increase followed by a 50% decrease does not return you to the start (100 → 150 → 75).
- Always divide by the original value when computing percentage change, not the new one.
Frequently asked questions
What is a percentage?+
A percentage is a ratio expressed out of 100. So 25% means 25 per 100, or 0.25 as a decimal. Percentages let you compare quantities of different sizes on a common scale.
How do I find X% of a number?+
Multiply the number by X and divide by 100. For example, 15% of 240 = 240 × 15 ÷ 100 = 36.
How do I calculate what percent one number is of another?+
Divide the part by the whole and multiply by 100. If 45 out of 180 students passed, that's 45 ÷ 180 × 100 = 25%.
How do I find the percentage change?+
Percentage change = (new − old) ÷ old × 100. A positive result is an increase, negative is a decrease.
Is percentage increase the same as percentage points?+
No. Going from 20% to 25% is a 5 percentage-point rise but a 25% relative increase. Journalists often confuse the two.