Percentage Calculator is a free online tool from Tool Hub Zone that works out percentages in seconds. You can find a percent of a number, see what percent one number is of another, and calculate a percentage increase, decrease, or change. It is useful for discounts, grades, tips, taxes, and prices. No account is needed.
How to Use the Percentage Calculator
- Choose the type of calculation you need.
- Enter your numbers in the boxes.
- Read the answer that appears.
- Change a number to try another case.
Percentage Formulas at a Glance
| Question | Formula | Example |
|---|---|---|
| What is X% of Y? | Y × X ÷ 100 | 15% of 200 = 200 × 15 ÷ 100 = 30 |
| X is what percent of Y? | X ÷ Y × 100 | 50 is 50 ÷ 200 × 100 = 25% of 200 |
| Increase a number by X% | Y × (1 + X ÷ 100) | 80 + 25% = 80 × 1.25 = 100 |
| Decrease a number by X% | Y × (1 − X ÷ 100) | 80 − 25% = 80 × 0.75 = 60 |
| Percentage change | (New − Old) ÷ Old × 100 | From 40 to 50: 10 ÷ 40 × 100 = 25% |
How Do I Calculate a Discount?
Take the discount percentage of the original price, then subtract it. For a jacket priced at 2,500 with 20% off, the discount is 2,500 × 20 ÷ 100 = 500, so the final price is 2,000. A shortcut is to multiply the price by 0.80, which gives the same answer in one step.
How Do I Find the Original Price After a Discount?
This is a common mistake. If an item costs 800 after a 20% discount, you cannot add 20% back to 800. The 800 is 80% of the original, so divide: 800 ÷ 0.80 = 1,000. The original price was 1,000.
How Do I Calculate a Percentage Change?
Subtract the old value from the new one, divide by the old value, and multiply by 100. A positive result means an increase and a negative result means a decrease. Going from 50 to 40 is a change of −20%, because (40 − 50) ÷ 50 × 100 = −20.
Notice that going from 40 to 50 is +25%, but going from 50 back to 40 is −20%. The two changes are different because each one is measured against a different starting value.
Why Does +50% Then −50% Not Return to the Start?
Start with 100 and add 50%, and you get 150. Now take away 50% of 150, which is 75, and you are left with 75, not 100. Each percentage is applied to a new base, so equal-looking percentages do not cancel each other out.
Percent vs. Percentage Points
These are often mixed up in news and reports. If an interest rate rises from 10% to 15%, it has gone up by 5 percentage points. In percent terms, though, the rate has grown by 50%, since 5 ÷ 10 × 100 = 50. Use percentage points for the plain difference between two percentages, and percent for the relative change.
Everyday Uses
- Shopping: Work out sale prices and compare deals.
- School: Turn marks into a percentage, for example 42 out of 60 is 70%.
- Tips and service charges: A 10% tip on a bill of 1,200 is 120.
- Business: Measure growth in sales, traffic, or costs from one period to another.
- Savings and loans: Understand how an interest rate affects an amount.
Tips for Accurate Results
- Check which number is the whole (the base). Most mistakes come from using the wrong one.
- Do not type the percent sign if the box asks only for a number.
- Round at the end, not in the middle of a calculation.
- If your numbers use different units, such as kilograms and grams, convert them first with the Unit Converter.
- For health-related ratios, such as body mass index, use the BMI Calculator.
Frequently Asked Questions
Is the percentage calculator free?
Yes. It is free to use, and you do not need to sign up.
Does it work on a phone?
Yes. You can use it in a browser on a phone, tablet, or computer.
Can I enter decimals?
Yes. You can use numbers such as 12.5 for the percentage or the amount.
Is the result financial advice?
No. The tool only does the math. For money decisions, please check the numbers with a qualified professional.
Last updated: October 11, 2026
