Percentage Calculator
Solve common percentage questions: a percentage of a value, one value as a percentage of another, or the base value from a part and percentage.
How it works
The selected mode determines the formula: part = percent ÷ 100 × base; percent = part ÷ whole × 100; base = part ÷ (percent ÷ 100).
Formula / calculation method
percent of a number = base × percent ÷ 100what percent = part ÷ base × 100base from percent = part ÷ (percent ÷ 100)
Worked examples
- 20% of 150 is 30.
- 30 is 20% of 150, and if 30 is 20% of a number, that number is 150.
When this tool helps
Useful for discounts, grades, budgets, statistics, comparisons, commissions, tax checks, targets, and everyday proportional calculations.
Related calculations: GPA calculator, weighted grade calculator, and final grade calculator.
Browse this topic: Percentage, Ratio & Finance Calculators · Percentage & Finance Formula Guide.
Quick reference
| Input | Result |
|---|---|
| 20% of 150 | 30 |
| 30 of 150 | 20% |
| 30 is 20% of ? | 150 |
Accuracy and definitions
Percentage calculations are direct arithmetic. Division-based modes require a non-zero denominator or percentage.
Methodology & verification
- Method
- The selected mode determines the formula: part = percent ÷ 100 × base; percent = part ÷ whole × 100; base = part ÷ (percent ÷ 100).
- Verification
- The displayed formula is cross-checked against Solveberry regression cases before release. Calculator inputs and results stay in the browser.
- Last reviewed
- 2026-08-19
Results are calculated locally in your browser. Optional analytics do not include calculator input values or results.
Common questions
What does percent mean?
Percent means per hundred, so 20% is equivalent to 20 ÷ 100 or 0.2.
Why can some percentage calculations be undefined?
If the formula requires division by zero, such as asking what percentage a value is of zero, the percentage is undefined.
Can I use decimal values?
Yes. The calculator accepts decimal values where they are mathematically valid for the selected calculation.
How should I verify an important result?
Use the displayed formula to reproduce the calculation independently, especially before making financial, legal, engineering or other consequential decisions.