How to Use the Percentage Calculator
This page explains how each of the three calculators on percentify.org works, with step-by-step instructions and worked examples.
Calculator 1 – What is X% of Y?
How it works
Enter a percentage in the first field and a number in the second field, then click Calculate (or press Enter). The result is X% of Y, calculated as Y × X ÷ 100.
Worked examples
| Question | Calculation | Answer |
|---|---|---|
| What is 10% of 200? | 200 × 10 ÷ 100 | 20 |
| What is 15% of 80? | 80 × 15 ÷ 100 | 12 |
| What is 25% of 360? | 360 × 25 ÷ 100 | 90 |
| What is 7.5% of 1000? | 1000 × 7.5 ÷ 100 | 75 |
| What is 20% of 45? | 45 × 20 ÷ 100 | 9 |
Common uses: calculating sales tax, tips, discounts, and commission amounts.
Calculator 2 – X is what percent of Y?
How it works
Enter a number in the first field and a second number in the second field, then click Calculate. The result tells you what percentage the first number is of the second, calculated as (X ÷ Y) × 100.
Worked examples
| Question | Calculation | Answer |
|---|---|---|
| 30 is what % of 150? | (30 ÷ 150) × 100 | 20% |
| 45 is what % of 180? | (45 ÷ 180) × 100 | 25% |
| 7 is what % of 28? | (7 ÷ 28) × 100 | 25% |
| 12 is what % of 96? | (12 ÷ 96) × 100 | 12.5% |
| 55 is what % of 220? | (55 ÷ 220) × 100 | 25% |
Common uses: calculating test scores, survey results, budget proportions, and batting averages.
Calculator 3 – Percentage Increase or Decrease
How it works
Enter the starting value in the first field and the ending value in the second field, then click Calculate. The result is the percentage change, calculated as ((New − Old) ÷ Old) × 100. A positive result means an increase; a negative result means a decrease.
Worked examples
| Scenario | From | To | Change |
|---|---|---|---|
| Price increase | $80 | $100 | +25% |
| Salary cut | $60,000 | $54,000 | −10% |
| Weight loss | 200 lbs | 185 lbs | −7.5% |
| Revenue growth | $1,200,000 | $1,500,000 | +25% |
| Temperature drop | 20°C | 15°C | −25% |
Common uses: comparing prices over time, tracking fitness progress, measuring business growth or decline.
Tips and Troubleshooting
Keyboard navigation
Mouse: Click any input field to select it, then click
Calculate to get the result.
Keyboard: Use Tab to move to the next field,
Shift+Tab to move to the previous field, and Enter
to calculate.
Decimal and thousands separators
You can use either a dot (.) or a comma (,) as a decimal separator —
both are accepted. Do not use thousands separators (e.g.,
do not type 1,000 or 1.000 for one thousand). Enter the number as
1000 instead.
Error handling
If there is a problem with your input, the result field will be empty and the field containing the error will be highlighted in red. Check that both fields contain valid numbers and try again.
Browser requirements
Percentage Calculator requires JavaScript to be enabled in your browser. All modern browsers (Chrome, Firefox, Safari, Edge) support this by default.