Percentage Calculator — Free Online % Calculator
By RupeesCalc Editorial Team · Reviewed by a SEBI-registered financial planner · Last updated:
What is a Percentage Calculator?
A percentage calculator handles the 5 most common percentage problems instantly — finding X% of a number, calculating what % one number is of another, computing percentage change, increasing/decreasing by a percentage, and reverse percentage. No formula memorisation needed.
Percentage Formulas
| Question | Formula | Example |
|---|---|---|
| What is 15% of 200? | (15 ÷ 100) × 200 | = 30 |
| 30 is what % of 200? | (30 ÷ 200) × 100 | = 15% |
| % change from 80 to 100 | ((100−80) ÷ 80) × 100 | = +25% |
| 500 increased by 20% | 500 × (1 + 20/100) | = 600 |
| 30 is 15% of what? | 30 ÷ (15 ÷ 100) | = 200 |
Common Uses of Percentage Calculations
- Discounts & shopping: 30% off ₹2,000 = ₹2,000 × 0.70 = ₹1,400
- Tax calculations: 18% GST on ₹1,000 = ₹1,180 total
- Exam marks: 425/500 = 85% score
- Salary hikes: ₹50,000 + 10% hike = ₹55,000
- Investment returns: ₹1L grew to ₹1.25L = 25% gain
- Tip calculation: 15% tip on $60 bill = $9
Note: Percentage increase and decrease are not symmetric. Increasing by 50% then decreasing by 50% gives you 75% of the original value, not 100%. Always calculate on the correct base value.
Frequently Asked Questions
How do you calculate a percentage of a number?
To find X% of Y: multiply Y by X and divide by 100. Formula: Result = (X ÷ 100) × Y. Examples: 15% of 200 = (15/100) × 200 = 30. 25% of 80 = (25/100) × 80 = 20. 7.5% of 1000 = (7.5/100) × 1000 = 75. Quick shortcut: To find 10%, move decimal point one place left (10% of 350 = 35). To find 5%, halve the 10% answer (5% of 350 = 17.5). To find 1%, move decimal two places left (1% of 350 = 3.5).
How do you calculate what percentage one number is of another?
To find what percentage A is of B: divide A by B and multiply by 100. Formula: Percentage = (A ÷ B) × 100. Examples: 30 is what % of 200? = (30/200) × 100 = 15%. 45 is what % of 180? = (45/180) × 100 = 25%. 7 is what % of 28? = (7/28) × 100 = 25%. Real-world use: Your test score is 72/90 — what %? = (72/90) × 100 = 80%. You spent ₹3,500 out of ₹15,000 budget — what %? = (3500/15000) × 100 = 23.3%.
How do you calculate percentage change?
Percentage change formula: % Change = ((New Value − Old Value) ÷ Old Value) × 100. If positive = increase. If negative = decrease. Examples: Price increases from ₹80 to ₹100: ((100−80)/80) × 100 = +25% increase. Salary drops from $60,000 to $54,000: ((54000−60000)/60000) × 100 = −10% decrease. Stock price moves from $150 to $180: ((180−150)/150) × 100 = +20% gain. Important: % increase and % decrease are NOT symmetrical. A 50% increase followed by a 50% decrease returns you to 75% of the original (not 100%).
How do you add or subtract a percentage from a number?
To increase a number by X%: New Value = Original × (1 + X/100). To decrease a number by X%: New Value = Original × (1 − X/100). Examples: Increase 500 by 20%: 500 × 1.20 = 600. Decrease 500 by 20%: 500 × 0.80 = 400. Price of ₹1,200 with 18% GST added: 1,200 × 1.18 = ₹1,416. Salary of $50,000 with 8% hike: 50,000 × 1.08 = $54,000. Discount: Product costs ₹2,000 with 15% off: 2,000 × 0.85 = ₹1,700.
What is reverse percentage?
Reverse percentage finds the original number when you know what percentage it represents. Formula: Original = Known Value ÷ (Percentage / 100). Examples: 30 is 15% of what number? Original = 30 ÷ 0.15 = 200. A shirt costs ₹850 after a 15% discount — what was the original price? Original = 850 ÷ 0.85 = ₹1,000. VAT-inclusive price is ₹1,180 at 18% VAT — what is the pre-tax price? Pre-tax = 1,180 ÷ 1.18 = ₹1,000. Common use: Working backwards from discounted or tax-inclusive prices.
What is the percentage difference formula?
Percentage difference measures the difference between two values relative to their average. Formula: % Difference = |V1 − V2| / ((V1 + V2) / 2) × 100. Example: Comparing 80 and 100: |80−100| / ((80+100)/2) × 100 = 20/90 × 100 = 22.2%. Note: Percentage difference is different from percentage change. Percentage change has a clear 'before' and 'after'. Percentage difference is used when comparing two equal-status values (e.g., two different prices). Use percentage change for before/after comparisons, percentage difference for comparing two alternatives.
How do you calculate percentage marks?
Percentage of marks = (Marks Obtained / Total Marks) × 100. Examples: You scored 425 out of 500: (425/500) × 100 = 85%. CBSE result: 456/500 = 91.2%. JEE score: 240/300 = 80%. To find marks needed for a target %: Marks needed = (Target % × Total Marks) / 100. To score 90% in a 500-mark exam: (90 × 500) / 100 = 450 marks needed. CGPA to percentage (approximate): CGPA × 9.5 = percentage (used by many Indian universities).
How do you calculate percentage profit or loss?
Percentage profit = ((Selling Price − Cost Price) / Cost Price) × 100. Percentage loss = ((Cost Price − Selling Price) / Cost Price) × 100. Examples: Bought for ₹500, sold for ₹600: Profit = (100/500) × 100 = 20% profit. Bought for ₹1,000, sold for ₹850: Loss = (150/1000) × 100 = 15% loss. Stock bought at $50, sold at $75: Profit = (25/50) × 100 = 50% gain. Property bought for ₹50L, sold for ₹70L: Profit = (20L/50L) × 100 = 40% gain.
How do you calculate tip percentage?
Tip amount = Bill Amount × (Tip % / 100). Total with tip = Bill Amount × (1 + Tip % / 100). Common tip percentages: 10% tip on $45 bill: $45 × 0.10 = $4.50 tip → $49.50 total. 15% tip on $60 bill: $60 × 0.15 = $9.00 tip → $69 total. 20% tip on $80 bill: $80 × 0.20 = $16 tip → $96 total. Quick mental math for 20% tip: Double the bill and move decimal left one place. $75 bill → double = $150 → 20% tip = $15. Use our percentage calculator above with the 'Increase by %' mode for any tip calculation.
How do you calculate percentage increase in salary?
Salary increase % = ((New Salary − Old Salary) / Old Salary) × 100. New salary after % increase = Old Salary × (1 + % / 100). Examples: Salary increases from ₹50,000 to ₹57,500: ((57,500 − 50,000) / 50,000) × 100 = 15% hike. What will ₹80,000 salary be after 12% hike? 80,000 × 1.12 = ₹89,600. After 3 years of 10% annual hikes from ₹60,000: Year 1: 66,000, Year 2: 72,600, Year 3: ₹79,860. Compound effect: Multiple percentage increases compound — a 10% hike each year for 3 years is NOT 30% total, it's 33.1%.
What is the percentage formula for GST calculation?
GST amount = Original Price × GST Rate / 100. Price with GST = Original Price × (1 + GST Rate / 100). To find original price from GST-inclusive price: Original = Inclusive Price / (1 + GST Rate / 100). Examples (18% GST): Product costs ₹1,000 → GST = ₹180 → Total = ₹1,180. Product costs ₹2,500 + 18% GST: 2,500 × 1.18 = ₹2,950. Bill shows ₹1,416 inclusive of 18% GST → Original = 1,416 / 1.18 = ₹1,200. Use our GST Calculator for split CGST/SGST/IGST breakdown.
Related Calculators
Sources & Methodology: Calculations are based on standard mathematical formulas. Tax slabs and rates are sourced from the Income Tax Department of India, Reserve Bank of India, and AMFI India. All calculators are for educational and planning purposes only — not financial advice. Last updated: .