Free Percentage Calculator - Calculate Percentages Instantly
Solve percentage problems instantly. Calculate discounts, changes, ratios, and more.
Formula & Methodology
The Percentage Calculator finds a part of a whole by multiplying the whole by the percentage divided by 100, and it works out percentage change by dividing the difference between the new and old values by the old value and multiplying by 100. The same tool handles both 'what is X% of Y' and 'how much did it grow' questions.
- Part = (Percent / 100) × Whole
- Percent Change = ((New − Old) / Old) × 100
Worked Example
Using the Percentage Calculator: apply the formula above to your input values. For instance, Part = (Percent / 100) × Whole, then Percent Change = ((New − Old) / Old) × 100. The tool performs each step instantly and shows the result.
Frequently Asked Questions
How do I calculate a percentage of a number?
Multiply the number by the percentage divided by 100 — for example, 20% of 50 is 50 × 0.20 = 10.
How do I find percentage change?
Subtract the old value from the new, divide by the old value, and multiply by 100 to get the percent increase or decrease.
How do I work out what percent one number is of another?
Divide the part by the whole and multiply by 100 to express it as a percentage.