PERCENTAGE
Calculator & Formula Tool
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Understanding Percentages
Percentages are a core part of daily life, used in everything from calculating tips at a restaurant to understanding interest rates on loans. A percentage is simply a number or ratio expressed as a fraction of 100.
Using the calculators below, you can solve three common types of percentage problems instantly. We also provide the specific formulas used so you can learn the math behind the magic.
Interactive Calculations
1. What is % of ?
2. is what % of ?
3. Change from to ?
4. Successive Changes (Start Value & up to 5 ±%)
5. If by %, adjust consumption by?
6. Population Growth / Decay
Real World Applications
Why is this important? Because percentages dictate financial decisions.
- Discounts: If a $50 shirt is 20% off, you save $10.
- Taxes: Sales tax adds a percentage to your subtotal.
- Growth: Businesses track year-over-year revenue growth in percentages.
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Frequently Asked Questions
What is the formula for Percentage?
The basic formula is:
(Part / Whole) × 100 = Percentage. For example, if you have 2 apples out of 10, that is (2/10)*100 = 20%.
How do I calculate percentage increase?
Subtract the old number from the new number, divide by the old number, and multiply by 100.
((New - Old) / Old) × 100.
How to convert a decimal to a percentage?
Simply multiply the decimal by 100. For example, 0.75 becomes 75%.
Formula for Successive Percentage Change?
Multiply the initial value by (1 + percentage/100) for each step.
Use negative values for decrements (e.g., -10 for 10% decrease).
Final = Initial × (1 + r1/100) × (1 + r2/100)...Use negative values for decrements (e.g., -10 for 10% decrease).
Formula for Price vs Consumption?
To keep expenditure constant:
If Price Increases by R%: Decrease Consumption by
If Price Decreases by R%: Increase Consumption by
If Price Increases by R%: Decrease Consumption by
R / (100 + R) × 100.If Price Decreases by R%: Increase Consumption by
R / (100 - R) × 100.
Formulas for Population Growth/Decay?
After n years (Growth):
n years ago (Growth):
After n years (Decay):
P(1 + R/100)nn years ago (Growth):
P / (1 + R/100)nAfter n years (Decay):
P(1 - R/100)n