%
Percentage Calculator
Calculate percentages, discounts & changes
Calculate percentages, discounts & changes
This percentage calculator handles three different percentage operations. Pick the one you need, plug in your numbers, and get instant results.
Find what percentage of a number equals. Super useful for calculating discounts, tips, or portions.
Example: What is 20% of 500? Answer: 100
Find what percentage one number is of another. Perfect for test scores, completion rates, or progress tracking.
Example: 50 is what % of 200? Answer: 25%
Calculate how much something increased or decreased. Essential for tracking growth, price changes, or performance improvements.
Example: From 80 to 100? Answer: 25% increase
Here are the three formulas this calculator uses. Understanding them helps you do quick mental math:
Formula 1: Finding a Percentage of a Number
Part = (Percentage / 100) × Whole
Use this when you want to find what amount equals a certain percentage. For example, to find 15% of 80: (15 / 100) × 80 = 12.
Formula 2: Finding What Percentage One Number Is
Percentage = (Part / Whole) × 100
Use this when comparing two numbers. To find what percent 25 is of 200: (25 / 200) × 100 = 12.5%.
Formula 3: Finding Percentage Change
Change% = ((New - Old) / Old) × 100
Use this to measure growth or decline. If a price goes from 100 to 150: ((150 - 100) / 100) × 100 = 50% increase.
These mental math shortcuts make percentage calculations faster without a calculator:
Pro Tip
Master these six tricks and you can estimate most percentages in your head. When you need exact numbers, use our calculator!
Percentages are everywhere in retail. When you see "30% off," stores want you to quickly understand the discount. Our calculator shows you the actual savings instantly. A 30% discount on a $200 item saves you $60, leaving you paying $140. Understanding percentages helps you spot real deals from fake discounts.
Interest rates, investment returns, loan APR, and salary increases all use percentages. If your bank offers 2% interest on savings or a mutual fund shows 8% annual returns, percentages help you compare and make smart financial decisions. Percentage change is particularly important for tracking investment performance over time.
Body fat percentage, BMI categories, and progress tracking all rely on percentages. If you want to track fitness progress, percentages let you compare your current stats to your starting point. A 10% weight loss of 200 pounds means losing 20 pounds, which is measurable and motivating.
Test scores are expressed as percentages to show performance relative to total points possible. A 92% on an exam means you answered questions worth 92 points out of 100. Grade cutoffs are also percentages (90-100% = A, 80-89% = B, etc.). Understanding your percentage helps you know where you stand academically.
Here are common errors to avoid:
These terms sound similar but mean completely different things. A percentage is a portion of 100 (so 50% = 50 out of 100). A percentile is your ranking compared to others. If you score in the 90th percentile on a test, you performed better than 90% of test-takers. Percentages are absolute values, while percentiles are relative rankings. This calculator handles percentages. For percentile information, you'd need to know the full distribution of all test scores.
To calculate a discount, use Mode 1 (What is X% of Y?). If an item costs $100 and has a 25% discount, calculate 25% of 100 to get $25, then subtract from the original price: $100 - $25 = $75 final price. Our calculator does this instantly. Many retailers prefer showing percentage discounts because they sound better than dollar amounts, even when they're mathematically equivalent. Always calculate the actual savings to comparison shop effectively.
Percentage increase means something grew in value. If sales went from 1000 units to 1250 units, that's a 25% increase. Percentage decrease means something lost value. If sales dropped from 1000 to 800 units, that's a 20% decrease. Both are calculated using Mode 3 (Percentage Change). The formulas are identical, just the direction changes. A positive result is an increase, and a negative result is a decrease.
Use Mode 2 (X is what % of Y?). If you scored 85 marks out of 100 total, enter 85 as the part and 100 as the whole to get 85%. This shows your performance as a percentage. Schools use percentages to standardize grades across different tests and subjects. If one exam is out of 100 points and another is out of 150, converting both to percentages lets you fairly compare your performance. This is essential for calculating GPA and academic standing.
Yes, absolutely. Percentages over 100% represent amounts greater than the whole. If you increased your investment from $1000 to $2500, that's a 150% increase (you now have 150% of your original amount, or 50% more). This happens regularly with growth metrics, performance bonuses, and inventory. In sales, if you exceed your target by 25%, you've achieved 125% of quota. Percentages above 100% are common and meaningful in many contexts.
Percentage error measures the difference between an estimated or measured value and the actual value. The formula is: ((Actual - Estimated) / Actual) × 100. If you estimated 50 people would attend and 45 actually came, your percentage error is ((45 - 50) / 45) × 100 = about 11% error. This is useful in science experiments, forecasting, and quality control. Percentage error helps quantify how far off a prediction or measurement is from reality, which is essential for assessing reliability and making improvements.
Beyond percentages, explore our full suite of useful calculators for grades, compatibility, and more.
Browse All Calculators