Percentage Calculator
Find X% of a number, what percent X is of Y, and percentage increase or decrease — three percentage calculators in one.
About the Percentage Calculator
This percentage calculator combines the three percentage problems people search for most into one page. Find what X% of a number is (15% of 200), work out what percent one number is of another (30 is what percent of 120?), and calculate the percentage increase or decrease between two values — all live, with no submit button.
Each section uses the standard formula. A percentage of a number is (percent ÷ 100) × value. A share is (part ÷ whole) × 100. Percentage change is (new − old) ÷ old × 100, with a positive result meaning an increase and a negative one a decrease. The tool handles decimals, so you can compute 12.5% of 87.30 just as easily as round numbers.
It is a daily driver for students checking exam marks, shoppers estimating discounts, business owners comparing month-on-month sales, and anyone splitting costs or working out tax. Because everything runs in the browser, results appear the instant you finish typing.
How to Use the Percentage Calculator
- 1Pick the section that matches your question — percent of a number, percent share, or percent change.
- 2Type the two numbers into that section's fields.
- 3Read the live result below the inputs.
- 4Repeat in any other section — each one works independently.
Frequently Asked Questions
How do I calculate the percentage of a number?
Multiply the number by the percentage and divide by 100. For example, 15% of 200 is 200 × 15 ÷ 100 = 30. In the first section of this calculator, enter 15 as the percentage and 200 as the number, and the answer appears instantly.
How do I find what percent one number is of another?
Divide the part by the whole and multiply by 100. For example, 30 out of 120 is 30 ÷ 120 × 100 = 25%. This is the formula used for exam scores, market share, completion rates and any "X out of Y" style question.
How is percentage increase or decrease calculated?
Percentage change equals (final value − initial value) ÷ initial value × 100. Going from 80 to 100 is a 25% increase; going from 100 to 80 is a 20% decrease. Note the two are not symmetric because the base value changes — a common source of confusion.
Why can't the initial value be zero in percentage change?
Percentage change divides by the initial value, and division by zero is undefined mathematically. Any growth from zero is infinite in percentage terms. If your starting value is zero, report the change in absolute terms instead (for example, "grew from 0 to 50 users").
Can I use this calculator for discounts and tax?
Yes. A 20% discount on 1,500 is simply 20% of 1,500 = 300 off, leaving 1,200. For a dedicated experience with bill splitting and final-price display, try our tip and discount calculator, or the GST calculator for Indian tax rates.