A percentage calculator helps solve common percent problems such as finding a percentage of a number, determining what percent one value is of another, calculating percentage change, and comparing values with percentage difference.
✔ Multiple percentage calculation modes
✔ Clear formulas and step-by-step working
✔ Useful for discounts, scores, prices, growth, and comparisons
How to Use the Percentage Calculator
- Choose the percentage calculation type that matches your problem.
- Enter the required values in the labeled fields.
- Select Calculate to see the answer, formula, and calculation steps.
You can also press Enter while typing in a calculator field. Use Copy Result to copy the full calculation and answer.
Percentage Formulas
What Is X% of Y?
(Percentage ÷ 100) × Number = Result
Use this when you already know the percentage and want to find that percentage of a number. For example, 20% of 150 is 30.
X Is What Percent of Y?
(Part ÷ Whole) × 100 = Percentage
Use this to find what percentage one value represents of another. For example, 30 is 20% of 150.
X Is Y% of What Number?
Part ÷ (Percentage ÷ 100) = Whole
Use this when you know the part and the percentage but need to find the original whole.
Percentage Change
((New Value − Original Value) ÷ |Original Value|) × 100
Percentage change measures the relative increase or decrease from an original value to a new value. A positive result indicates an increase and a negative result indicates a decrease.
Percentage Difference
|Value 1 − Value 2| ÷ ((|Value 1| + |Value 2|) ÷ 2) × 100
Percentage difference compares two values without treating either one as the original. This is useful for comparing independent measurements or results.
Increase or Decrease a Number by a Percentage
Increase: Number + (Percentage ÷ 100 × Number)
Decrease: Number − (Percentage ÷ 100 × Number)
This mode is useful for discounts, price increases, salary changes, markups, and similar calculations.
Worked Percentage Examples
Example 1: What Is 20% of 150?
- 20 ÷ 100 = 0.20
- 0.20 × 150 = 30
Answer: 20% of 150 is 30.
Example 2: 30 Is What Percent of 150?
- 30 ÷ 150 = 0.20
- 0.20 × 100 = 20%
Answer: 30 is 20% of 150.
Example 3: Percentage Increase from 80 to 100
- 100 − 80 = 20
- 20 ÷ 80 = 0.25
- 0.25 × 100 = 25%
Answer: The value increased by 25%.
Example 4: Percentage Difference Between 120 and 100
- |120 − 100| = 20
- (120 + 100) ÷ 2 = 110
- 20 ÷ 110 × 100 ≈ 18.18%
Answer: The percentage difference is approximately 18.18%.
Example 5: 30% Discount on $200
- 30% of 200 = 60
- 200 − 60 = 140
Discount amount: $60. Final price: $140.
Percentage Change vs Percentage Difference
Percentage change uses a specific original value as the reference and shows direction. For example, moving from 80 to 100 is a 25% increase.
Percentage difference treats both values equally and compares their absolute difference with their average. It is better when neither value should be treated as the baseline.
Percentage Points vs Percent Change
Percentage points and percent change are not the same. If a rate moves from 20% to 25%, it increased by 5 percentage points. Relative to the original 20%, however, that is a 25% increase.
Common Percentage Mistakes
- Using the wrong reference value: Percentage change is normally measured relative to the original value.
- Confusing “X% of Y” with “X is what percent of Y”: These are different calculations and use different formulas.
- Confusing percentage points with percent change: A move from 10% to 15% is 5 percentage points but a 50% relative increase.
- Forgetting to multiply by 100: A ratio of 0.25 represents 25%, not 0.25%.
- Using percentage difference when direction matters: Use percentage change when you have an original and a new value.
Common Uses of Percentage Calculations
Shopping: Calculate discount amounts and final sale prices.
Education: Convert obtained marks into a percentage score.
Business: Measure revenue growth, cost changes, and performance differences.
Personal finance: Estimate increases, decreases, taxes, interest-related percentages, and savings.
Comparisons: Compare independent measurements using percentage difference.
How to Verify a Percentage Answer
You can often verify a percentage calculation by reversing the operation. For example, if 20% of 150 equals 30, check the relationship with: 30 ÷ 150 × 100 = 20%.
For calculations involving division, you can also use our Division Calculator. For proportional relationships, try the Ratio Calculator.
Percentage Examples at a Glance
| Problem | Calculation | Result |
|---|---|---|
| 20% of 150 | (20 ÷ 100) × 150 | 30 |
| 30 is what % of 150? | (30 ÷ 150) × 100 | 20% |
| 30 is 20% of what? | 30 ÷ 0.20 | 150 |
| 80 to 100 | ((100 − 80) ÷ 80) × 100 | 25% increase |
| 120 vs 100 | 20 ÷ 110 × 100 | 18.18% difference |
| Decrease 200 by 30% | 200 − 60 | 140 |
Frequently Asked Questions
A percentage calculator solves common percent problems, including finding a percentage of a number, determining what percent one value is of another, calculating percentage change, and finding percentage difference.
To find what percentage one number is of another, divide the part by the whole and multiply by 100. For example, 25 ÷ 200 × 100 = 12.5%.
Yes. Choose the Percentage Change mode, then enter the original and new values. The calculator shows whether the result is an increase or decrease and displays the calculation steps.
Yes. Choose Increase / Decrease, select Decrease, and enter the original price and discount percentage. The calculator shows both the discount amount and the final price.
Yes. Choose “X is what % of Y?”, enter your obtained marks as the Part and total marks as the Whole, then calculate the percentage score.
Yes. A percentage can be greater than 100 when the compared value is larger than the reference whole. For example, 150 is 150% of 100.
Percentage change compares a new value with a specific original value and shows direction. Percentage difference treats both values equally and compares their absolute difference with their average.
Percentage points describe the absolute difference between two percentages. A change from 20% to 25% is 5 percentage points, even though the relative increase is 25%.
Calculation Method
How we calculate: Each calculator mode uses the standard percentage formula displayed with the result. The tool applies that formula directly to the entered values and generates step-by-step working so the answer can be checked independently.
Need another basic math tool? Try the Multiplication Calculator, Division Calculator, Ratio Calculator, or the Fraction to Decimal Converter.
