Percentage Calculator: Formula, Examples, and Everyday Uses
Learn how to calculate percentages, find percentage increase or decrease, and solve everyday percentage problems with simple formulas and examples.
Percentages help explain marks, discounts, price changes, budgets, and many other everyday calculations. A Percentage Calculator makes it easier to find a percentage of a number, work out what percentage one value is of another, or compare a change between two values.
What Does Percent Mean?
Percent means “per hundred.” For example, 25% means 25 out of every 100. Percentages make it easier to compare values even when the totals are different.
Useful Percentage Formulas
Find a percentage of a number
Result = (Percentage ÷ 100) × Number
Example: What is 20% of ₹1,500?
20 ÷ 100 × 1,500 = ₹300.
Find what percentage one number is of another
Percentage = (Part ÷ Whole) × 100
Example: You scored 72 marks out of 90.
72 ÷ 90 × 100 = 80%.
Calculate percentage increase
Percentage Increase = ((New Value − Old Value) ÷ Old Value) × 100
If a price rises from ₹800 to ₹920, the increase is ₹120. The percentage increase is 120 ÷ 800 × 100 = 15%.
Calculate percentage decrease
Percentage Decrease = ((Old Value − New Value) ÷ Old Value) × 100
If a product drops from ₹2,000 to ₹1,700, the decrease is ₹300, or 15%.
How to Use a Percentage Calculator
- Choose the calculation you need: percentage of a number, part-to-whole percentage, or percentage change.
- Enter the relevant values.
- Calculate the result.
- Check that you selected the correct starting value when measuring a change.
Common Mistakes to Avoid
- Using the wrong base value: Percentage change is calculated relative to the original value.
- Confusing percentage points with percent change: A rate moving from 10% to 15% rises by 5 percentage points, which is a 50% relative increase.
- Rounding too early: Keep full precision during calculations and round the final answer.
- Dividing by zero: A percentage relative to a zero original value is undefined using the standard percentage-change formula.
Frequently Asked Questions
How do I calculate 10% quickly?
Move the decimal point one place left, or divide the amount by 10. For example, 10% of ₹450 is ₹45.
How do I calculate marks percentage?
Divide marks obtained by total possible marks and multiply by 100. Make sure both values use the same marking scale.
Can a percentage be greater than 100%?
Yes. If a value is larger than the reference total, the resulting percentage can exceed 100%.
Final Thoughts
A Percentage Calculator is useful for school results, shopping discounts, business figures, and tracking changes. Choose the formula that matches your question and always verify which value is the base.
This article is for general educational purposes. Check your inputs and rounding requirements when using percentages for official or financial calculations.