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Percentage Calculator

Calculate percentages, increases, decreases, and ratios

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Enter your values below

The number to calculate percentage from

The percentage to calculate (e.g., 25 for 25%)

For calculating what percentage a value is of a total

About Percentage Calculator

Calculate percentages, percentage increases/decreases, and determine what percentage one number is of another. Perfect for discounts, tips, taxes, and financial calculations.

Why Use This Tool?

  • ✓ Instantly calculate any percentage operation - find X% of a number, determine what % one number is of another, calculate increases/decreases all in one place
  • ✓ Avoid common percentage mistakes (like thinking a 50% increase followed by 50% decrease returns to original - it doesn't!) with accurate calculations
  • ✓ Compare discounts instantly - see if '30% off' or 'buy 2 get 1 free' (33% off) is better, calculate final prices with multiple discounts and taxes
  • ✓ Perfect for shopping, grades, finance, and statistics - more versatile than your phone's basic calculator which requires you to do the percentage math yourself
  • ✓ Free and instant - no ads interrupting your shopping decisions, no account needed, works on any device in your browser

Formulas

  • Percentage of value: \text{Result} = \frac{\text{value} \times \text{percentage}}{100}
  • Value as percentage: \text{Percentage} = \frac{\text{value}}{\text{total}} \times 100
  • Percentage increase: \text{New} = \text{value} \times (1 + \frac{\text{percentage}}{100})
  • Percentage decrease: \text{New} = \text{value} \times (1 - \frac{\text{percentage}}{100})

Common Calculations

  • Percentage of a number: What is 25% of 200? = 50
  • Percentage ratio: What percentage is 50 of 200? = 25%
  • Percentage increase: 200 + 25% = 250
  • Percentage decrease: 200 - 25% = 150

Real-World Examples

  • Sales tax: Calculate 8.5% tax on $100 purchase
  • Discounts: Find 20% off original price
  • Tips: Calculate 15% tip on restaurant bill
  • Interest: Determine 5% annual interest on savings
  • Growth rates: Calculate percentage change over time

How to Use

  • Enter the base value you want to calculate from
  • Enter the percentage (just the number, e.g., 25 for 25%)
  • Optionally enter a total to find what percentage your value represents
  • View all calculated results including increases and decreases

Common Questions

  • Q: How do I calculate percentage change between two numbers? Formula: ((New - Old) / Old) × 100. For increase from 50 to 75: ((75-50)/50) × 100 = 50% increase. For decrease from 100 to 80: ((80-100)/100) × 100 = -20% decrease. Common mistake: dividing by the new number instead of old. If price goes from 20 to 25, that's 5 increase on 20 base = 25% increase, not on $25 base which would be 20%. Always divide by the original (old) value.
  • Q: If something increases 50% then decreases 50%, do you end up at the original value? No! This is a common misconception. Start with 100. Increase 50%: 100 × 1.5 = 150. Decrease 50%: 150 × 0.5 = 75. You end at 75, not 100! The 50% decrease applies to the larger number (150), so you lose more than you gained. Percentages aren't commutative. To return to original after 50% increase, you need ~33% decrease: 150 × 0.667 ≈ 100.
  • Q: What's the difference between percentage points and percent change? Percentage points measure absolute difference in percentages. Percent change measures relative change. If interest rate goes from 5% to 8%, that's +3 percentage points (8-5=3) but a 60% increase ((8-5)/5 × 100). If approval rating drops from 50% to 45%, that's -5 percentage points but a -10% decrease. Media often confuses these - '5 point drop' is different from '5% drop'. For rates, always clarify which you mean.
  • Q: How do I work backwards from a discounted price to find the original? If you know final price and discount %, divide by (100 - discount%) × 100. Sale item is 60 after 25% off. Original: 60 ÷ 0.75 = 80. Check: 80 × 0.25 = 20 off, 80 - 20 = 60 ✓. Another example: paid 85 after 15% discount. Original: 85 ÷ 0.85 = $100. This is 'reverse percentage' - dividing instead of multiplying because you're undoing the discount.
  • Q: How do multiple discounts stack - do you add them? No, never add sequential discounts! Each applies to the reduced price. A 100 item with 20% off then additional 10% off: First: 100 × 0.8 = 80. Second: 80 × 0.9 = 72 final. Total savings: 28 = 28% (not 30%). To calculate stacked discount: multiply the 'keep' percentages: 0.8 × 0.9 = 0.72, meaning you pay 72%, so 28% off. '20% + 10% off' really means ~28% off, not 30%. Stores use this to make deals seem bigger than they are.

Pro Tips & Best Practices

  • 💡 Mental math shortcuts for common percentages: 10% = divide by 10 (move decimal left), 5% = half of 10%, 1% = move decimal left twice. To find 15% of 80: 10% = 8, 5% = 4, total = 12. For 25% (quarter), divide by 4. For 33% (third), divide by 3. For 75% (three-quarters), divide by 4 then multiply by 3. These let you calculate tips, discounts, and taxes instantly without a calculator - impress friends and make faster shopping decisions.
  • 💡 Always calculate sales tax on the discounted price, not original: Common mistake: item is 100, 20% off = 80, 8% sales tax. WRONG: 100 × 0.08 = 8 tax. RIGHT: 80 × 0.08 = 6.40 tax. You pay tax on what you actually buy (80), not original price. Final: 80 + 6.40 = 86.40. To calculate in one step: original × (1 - discount%) × (1 + tax%), here: 100 × 0.8 × 1.08 = 86.40. This saves money - $1.60 in this example.
  • 💡 Understand 'up to' vs 'at least' percentage changes: In finance and statistics, direction matters. Stock down 50% needs 100% gain to recover (not 50%). If you lose 50% of 100 = 50 left, you need 50 gain on 50 base = 100% increase to return to $100. Conversely, 100% increase only needs ~33% decrease to undo. Always calculate from current value, not original. This is why market crashes are harder to recover from - 50% crash needs 100% rally.
  • 💡 Compare discounts fairly using final price, not percentage: Store A: 100 item, 30% off = 70. Store B: 90 item, 20% off = 72. Store A is better despite smaller original price. Or: Store A offers 40% off 150 = 90. Store B offers 30% off 120 = 84. Store B wins! Don't assume bigger percentage means better deal. Also beware 'original price' inflation where stores mark up before 'discounting' back to normal price. Use this calculator to find true final costs.
  • 💡 Grade calculations with percentages: To find needed score on final exam, use: (target grade - current weighted %) / final weight. If you have 75% and want 80% total, with final worth 40%: (80 - 75×0.6) / 0.4 = (80 - 45) / 0.4 = 87.5% needed on final. Or to calculate current grade: sum (score × weight) for each assignment. Quiz 80% (20% weight): 80×0.2=16. Test 90% (30% weight): 90×0.3=27. Current: 16+27=43% of total so far. If 50% remains, you can still reach any grade between 43% and 93%.

When to Use This Tool

  • Shopping & Discounts: Calculate final prices after sales discounts and coupons, compare deals (30% off vs $20 off - which is better?), determine if sale prices beat competitor prices, calculate savings on Black Friday/Cyber Monday deals
  • Finance & Investing: Calculate investment returns and losses, determine compound interest percentages, analyze stock price changes, compare savings account interest rates (APY), calculate loan interest or down payment percentages
  • School & Grading: Calculate current class grades from weighted assignments, determine needed score on final exam to reach target grade, convert raw scores to percentage grades, calculate GPA contributions
  • Work & Business: Calculate sales commission (7% of $50,000 sales), determine profit margins (profit/revenue × 100), calculate percentage of budget used, analyze year-over-year growth rates, determine raise or salary increase percentages
  • Health & Fitness: Calculate percentage of daily calorie goals achieved, determine body fat percentage changes, track weight loss progress as percentage, calculate macro nutrient percentages (40/30/30 carbs/protein/fat)
  • Taxes & Tips: Calculate sales tax on purchases (varies by state: 0-10%), determine restaurant tips (15-20% of bill), calculate property tax rates, estimate tax refunds as percentage of income

Related Tools

  • Try our Tip Calculator for specialized restaurant tipping with bill splitting features beyond basic percentages
  • Use our Loan Calculator to calculate percentage-based interest rates, APR, and total interest paid over loan terms
  • Check our BMI Calculator for health percentiles and body mass percentage categories based on height and weight
  • Explore our Scientific Calculator for complex percentage calculations involving exponents, logarithms, or multi-step operations

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