How to Calculate Percentages — All 4 Methods Explained
A percentage is a way to express a number as a fraction of 100. The word "percent" comes from the Latin per centum, meaning "by the hundred." Percentages are used everywhere in daily life — from GST and discounts to salary hikes, investment returns, and exam scores. This calculator solves all four core percentage problem types: proportional share, parts-to-whole ratio, growth/decay change, and value operations.
Percentage Formulas for All 4 Scenarios
Example: 20% of 500 = (20 ÷ 100) × 500 = 100
Example: 100 is what % of 500? → (100 ÷ 500) × 100 = 20%
Example: 200 to 250 → ((250 − 200) ÷ 200) × 100 = +25%
Example: 1000 increased by 15% → 1000 × 1.15 = 1,150 | Decreased by 15% → 1000 × 0.85 = 850
Real-World Percentage Examples
| Problem Type | Question | Formula Used | Answer |
|---|---|---|---|
| GST Calculation | GST @ 18% on ₹5,000 item? | 18% of 5000 = (18÷100)×5000 | ₹900 |
| Salary Hike | ₹50,000 salary with 12% hike? | 50000 × (1 + 12/100) | ₹56,000 |
| Discount Savings | 30% off ₹2,500 product? | 2500 × (1 − 30/100) | ₹1,750 |
| Exam Score | Got 72 out of 80 marks — what %? | (72 ÷ 80) × 100 | 90% |
| Investment Return | Portfolio grew from ₹1L to ₹1.35L | ((1.35−1.00) ÷ 1.00) × 100 | +35% |
Frequently Asked Questions
Percentage Increase = ((New Value − Original Value) ÷ Original Value) × 100. Example: A salary raised from ₹40,000 to ₹46,000 = ((46000 − 40000) ÷ 40000) × 100 = 15% increase. Always use the original value as the denominator.
To find X% of Y: multiply Y by X and divide by 100. Formula: Result = (X ÷ 100) × Y. Example: 15% of ₹2,000 = (15 ÷ 100) × 2000 = ₹300. This is used for GST, discounts, commission, and tip calculations.
To find what % Part is of Total: % = (Part ÷ Total) × 100. Example: 45 marks out of 60 → (45 ÷ 60) × 100 = 75%. This is used for exam scores, market share, and attendance rates.
Percentage Decrease = ((Original Value − New Value) ÷ Original Value) × 100. Example: Price dropped from ₹800 to ₹680 → ((800 − 680) ÷ 800) × 100 = 15% decrease. Use Scenario 3 above to solve this instantly.
Percentage = a proportion out of 100 (e.g., 80% score means 80 out of 100 marks). Percentile = a ranking indicator. If you scored in the 90th percentile, you scored better than 90% of all test-takers, regardless of your raw percentage score. NEET, JEE, and CAT results are expressed in percentiles.
If you know the final amount after a percentage change, reverse the formula: Original = Final ÷ (1 + Rate/100) for increases, or Original = Final ÷ (1 − Rate/100) for discounts. Example: A product after 20% discount costs ₹800. Original price = 800 ÷ 0.80 = ₹1,000.
GST Amount = Price × (GST Rate ÷ 100). Total Price = Price + GST Amount. Example: Item costs ₹1,000 + GST 18%: GST = ₹180, Total = ₹1,180. To find base price from GST-inclusive price: Base = Inclusive Price ÷ (1 + 18/100) = ₹1,180 ÷ 1.18 = ₹1,000. Use our GST Calculator for full breakdown.
Compound growth applies a percentage gain repeatedly each period. Formula: Final Value = Initial × (1 + Rate/100)^n where n = number of periods. Example: ₹1 Lakh at 10% for 5 years compounded annually = 1,00,000 × (1.10)^5 = ₹1,61,051. For compound interest, use our Compound Interest Calculator.