Percentage Calculator
Perform percentage calculations easily with three modes.
Input Information
Result
Enter values to calculate
Percentage Calculator is a tool that makes it easy to perform percentage (%) calculations frequently used in daily life and work. It is used in various situations such as discount rate calculations, tax calculations, grade analysis, and return rate comparisons.
This calculator provides three basic percentage calculation modes:
- What is B% of A? - Calculates a certain proportion of a specific value.
- A is what % of B? - Finds the ratio (percentage) between two values.
- A +/- B% - Applies a percentage to a value and calculates the final value after increase or decrease.
Percentage is a mathematical expression meaning "one hundredth," making it easy to compare and express ratios. For example, 50% means half, 25% means one-quarter.
Term Glossary
- Percentage (%)
- A mathematical expression representing a ratio based on 100.
- Ratio
- Represents the size relationship between two values; percentage expresses this ratio based on 100.
- Decrease Rate
- The rate at which a value has decreased, which can be expressed as a negative percentage.
- 1
Choose the calculation type
Select the calculation type: 'B% of A' (proportion of a value), 'A is what % of B' (ratio comparison), or 'A +/- B%' (applying a change rate).
- 2
Enter your values
Enter the base value, percentage, or the two values to compare depending on the chosen type. For example: base value 150 and percentage 20.
- 3
Calculate
Press the calculate button to see the result. The calculator computes and displays the percentage result instantly based on your input.
- 4
Read the result
Review the result value and interpret it in your real-life context (discounted price, return rate, score, etc.). A negative result indicates a decrease.
Example 1 — Proportion of a value
What is 20% of 150? Formula: 150 × (20/100) = 150 × 0.20 = 30. So 20% of 150 is 30.
Example 2 — Ratio comparison
45 is what percent of 180? Formula: (45/180) × 100 = 0.25 × 100 = 25%. So 45 is 25% of 180.
Example 3 — Percentage change
What is the percentage change from 50 to 60? Formula: (60 − 50) ÷ 50 × 100 = 20%. So it is a 20% increase.
Mode 1: B% of A
- A - Base value (total)
- B - Percentage value (%)
- Result: The value corresponding to B% of A
Mode 2: A is what % of B?
- A - Part value
- B - Whole value
- Result: The ratio (%) that A represents of the whole B
Mode 3: A +/- B%
- A - Original value
- B - Change rate (%). Positive for increase, negative for decrease
- Result: Final value after increase/decrease
Examples
Mode 1: 15% of 200,000 = 200,000 × 0.15 = 30,000
Mode 2: 30 is what % of 200? = (30/200) × 100 = 15%
Mode 3: 100,000 increased by 20% = 100,000 × 1.2 = 120,000
Real-Life Applications
- Shopping discounts: Actual price of a 30% discounted item at 59,900: 59,900 × 0.7 = 41,930
- Tax calculation: Price including 10% VAT: 10,000 × 1.1 = 11,000
- Return rate: If 10 million becomes 11.5 million, the return rate is 15%
- Test scores: 42 correct out of 50: (42/50) × 100 = 84%
Common Percentage Conversions
Did you know?
30% off plus another 30% off is NOT 60% off! A 100,000 item with 30% off → 70,000, then another 30% off → 49,000 (total 51% off). This is because the "base value" changes for each percentage.
QWhat is the formula for calculating percentage?
A percentage means one hundredth. To find 'B% of A', compute A × (B/100). For example, 20% of 150 is 150 × 0.20 = 30. To find 'what percent A is of B', compute (A / B) × 100.
QHow do you calculate percentage change?
Percentage change is calculated as (new value − old value) ÷ old value × 100. For example, an increase from 50 to 60 is (60 − 50) ÷ 50 × 100 = 20% increase. A decrease yields a negative result, representing the decrease rate.
QHow do I calculate a discount and the discounted price?
Discount amount = original price × discount rate. Discounted price = original price × (1 − discount rate). For example, a 59,900 item at 30% off costs 59,900 × 0.70 = 41,930.
QWhat is the difference between percentage (%) and percentage point (%p)?
Percentage (%) is a relative unit of ratio, while percentage point (%p) is the absolute difference between two percentage values. For example, an interest rate rising from 3% to 5% is a '2 percentage point increase', which is a 66.7% relative increase. The two are easily confused but mean different things.
QHow do you do reverse percentage calculations?
To find the whole when you know it is B% of it, divide the known value by (B/100). For example, if a discounted price is 70% of the original, the original = discounted price ÷ 0.70. So a 70,000 discounted price means the original was 70,000 ÷ 0.70 = 100,000.