Percentage Calculator

What is Percentage Calculator?

The Percentage Calculator handles multiple calculations: find X% of a number, calculate percentage change (increase or decrease), find what percentage one number is of another, and reverse-calculate the original value from a percentage result.

How to Calculate Percentage

1. Enter the base value
2. Enter the percentage to apply
3. Click Calculate to see the result and reverse calculations

How Percentage Calculator is Calculated

X% of Y = (X/100) × Y. Percentage increase = ((New − Old) / Old) × 100. Percentage decrease = ((Old − New) / Old) × 100. Reverse: If result = X% of ?, then ? = result × 100 / X.

Worked Example

What is 15% of ₹2,500? Answer: (15/100) × 2,500 = ₹375. Percentage increase from ₹200 to ₹250: ((250−200)/200) × 100 = 25% increase.

Common Use Cases

• Shop discount calculations
• Tax percentage computation
• Exam marks percentage
• Salary hike percentage calculation

Common Mistakes to Avoid

• Calculating percentage change using the wrong base — always divide by the original (old) value, not the new value.
• Adding percentages incorrectly — a 20% increase followed by a 20% decrease does NOT give you the original number (it gives 4% less).
• Confusing percentage points with percentages — going from 5% to 10% is a 5 percentage-point increase but a 100% increase.
• Using the wrong formula for discount stacking — two successive 20% discounts give 36% total discount, not 40%.

Related Guides

Why You Need This Calculator

Percentage calculations are used daily — from exam scores and discounts to tax rates and growth metrics. In Indian competitive exams like JEE, NEET, and UPSC, understanding percentile vs percentage is crucial. A 95 percentile in JEE means you scored better than 95% of candidates, which may correspond to only 45-50% marks depending on difficulty.

Calculator Features

• Calculate percentage of any number
• Percentage increase and decrease
• Percentage difference between two values
• Mark to percentage converter
• Discount and sale price calculator
• Percentage to fraction/decimal conversion

The Math Behind It

Percentage = (Part / Whole) × 100. Percentage Change = [(New – Old) / Old] × 100. Value after % change = Value × (1 ± %/100).

Calculation Example

Scored 432 out of 500: (432/500) × 100 = 86.4%. Price dropped from ₹2,000 to ₹1,600: change = [(1600–2000)/2000] × 100 = -20%.

Quick Reference

Common percentage calculation examples

Pro Tips & Expert Insights

• 💡 Percentage change formula: [(New – Old) / Old] × 100.
• 💡 For successive discounts: don't add them. 20% + 10% = 28% total discount, not 30%.
• 💡 In competitive exams, percentile rank ≠ percentage marks.
• 💡 Profit percentage is always calculated on cost price, not selling price.
• 💡 CAGR is more meaningful than simple average percentage growth.

Who Benefits From This?

Students calculating exam scores, shoppers calculating discounts, business analysts, and anyone working with data.