Percentage Calculator
Three percentage calculations in one tool. Select the type of calculation you need, enter your numbers, and get an instant result — no manual formula required.
The Three Percentage Formulas
What is X% of Y?
Result = (X ÷ 100) × Y
Example: What is 15% of 200? → (15 ÷ 100) × 200 = 30
Percentage change from X to Y
Result = ((Y − X) ÷ |X|) × 100
Example: Change from 50 to 75 → ((75 − 50) ÷ 50) × 100 = +50%
X is what % of Y?
Result = (X ÷ Y) × 100
Example: 30 is what % of 120? → (30 ÷ 120) × 100 = 25%
Common Percentage Uses
Percentages appear constantly in everyday life — from sales discounts and tax rates to investment returns, test scores, and nutritional labels. Understanding how to calculate them quickly is a practical skill with wide applications:
- Shopping: Calculating sale prices and discount savings
- Finance: Interest rates, investment returns, fee percentages
- Health: Macronutrient percentages, body fat percentage
- Work: Raise calculations, commission structures, growth rates
- Tipping: Restaurant tips based on bill amount
Frequently Asked Questions
- What is the basic percentage formula?
- The basic formula is: Percentage = (Part ÷ Whole) × 100. For example, if 30 out of 150 students passed a test, the pass rate is (30 ÷ 150) × 100 = 20%. To find a percentage of a number, use: Result = (Percentage ÷ 100) × Number.
- How do I calculate percentage increase or decrease?
- Percentage change = ((New Value − Old Value) ÷ |Old Value|) × 100. A positive result means an increase; a negative result means a decrease. For example, a price that goes from $80 to $100 is a 25% increase. A price that drops from $100 to $80 is a 20% decrease. Note that percentage increases and decreases are not symmetric.
- What is the difference between percentage points and percent change?
- Percentage points measure the arithmetic difference between two percentages. Percent change measures the relative change. If interest rates rise from 2% to 5%, that is a 3 percentage-point increase but a 150% percent change. This distinction matters in finance, polling, and economics reporting.
- How do I calculate 15% or 20% tip quickly?
- For a 10% tip, move the decimal point one place left (e.g., $64 → $6.40). For 20%, double that figure ($12.80). For 15%, take the 10% figure and add half of it ($6.40 + $3.20 = $9.60). Our percentage calculator handles any tip percentage instantly.
- What is percentage error and how is it calculated?
- Percentage error measures how far an estimated or experimental value is from the true or accepted value: Percentage error = (|Estimated − Actual| ÷ |Actual|) × 100. It is commonly used in science and engineering to evaluate measurement accuracy.