Percentage Calculator — Four Ways to Calculate Percentages
Our free percentage calculator handles four common percentage problems in one tool. Find what percent of a number is, calculate what percentage one number is of another, find the percentage increase or decrease between two values, or calculate the percentage difference between two numbers. All results appear instantly as you type.
How to Calculate a Percentage
Finding a Percentage of a Number
To find X percent of a number, multiply the number by the percentage expressed as a decimal (percentage ÷ 100).
Formula: Result = (Percentage ÷ 100) × Value
Example: What is 35% of 240? 35 ÷ 100 = 0.35. Then 0.35 × 240 = 84. So 35% of 240 = 84.
Finding What Percentage One Number Is of Another
To find what percentage a part is of a whole, divide the part by the whole and multiply by 100.
Formula: Percentage = (Part ÷ Whole) × 100
Example: 45 is what percent of 180? (45 ÷ 180) × 100 = 25%. So 45 is 25% of 180.
How to Calculate Percentage Change
Percentage Increase
Percentage increase measures how much a value has grown relative to its original amount.
Formula: % Increase = ((New − Original) ÷ Original) × 100
Example: A product price increased from $40 to $52. ((52 − 40) ÷ 40) × 100 = (12 ÷ 40) × 100 = 30% increase.
Percentage Decrease
Percentage decrease measures how much a value has fallen relative to its original amount.
Formula: % Decrease = ((Original − New) ÷ Original) × 100
Example: A product price dropped from $80 to $60. ((80 − 60) ÷ 80) × 100 = (20 ÷ 80) × 100 = 25% decrease.
Percentage Change vs Percentage Difference
These two calculations are often confused but serve different purposes:
| Calculation | When to use | Formula | Example |
|---|---|---|---|
| Percentage change | One value is the original/reference point | ((New − Old) ÷ Old) × 100 | Price went from $50 to $60 = 20% increase |
| Percentage difference | No defined original; comparing two equal values | (|A − B| ÷ ((A + B) ÷ 2)) × 100 | Difference between $50 and $60 = 18.18% |
Common Percentage Calculations Reference
Quick reference for the most frequently searched percentage calculations:
| Question | Answer | Formula used |
|---|---|---|
| What is 10% of 100? | 10 | 100 × 0.10 |
| What is 15% of 200? | 30 | 200 × 0.15 |
| What is 20% of 50? | 10 | 50 × 0.20 |
| What is 25% of 80? | 20 | 80 × 0.25 |
| What is 30% of 150? | 45 | 150 × 0.30 |
| What is 5% of 1000? | 50 | 1000 × 0.05 |
| 50 is what % of 200? | 25% | (50 ÷ 200) × 100 |
| 75 is what % of 300? | 25% | (75 ÷ 300) × 100 |
| 18 is what % of 72? | 25% | (18 ÷ 72) × 100 |
| From 50 to 75 = ? | 50% increase | ((75 − 50) ÷ 50) × 100 |
| From 100 to 80 = ? | 20% decrease | ((100 − 80) ÷ 100) × 100 |
| From 200 to 250 = ? | 25% increase | ((250 − 200) ÷ 200) × 100 |
Real-World Uses of Percentage Calculations
Finance and Investing
Percentage calculations are essential in finance. Investment returns, interest rates, tax rates, inflation, and portfolio changes are all expressed as percentages. For example, if a stock rises from $120 to $150, that is a 25% gain. If it falls back to $120, that is a 20% loss — not 25%, because the base has changed.
Shopping and Discounts
Quickly verify whether a sale price is accurate by calculating the percentage discount yourself. If an item was $85 and is now $68, that is a ((85 − 68) ÷ 85) × 100 = 20% discount.
School and Grades
Convert raw scores to percentages to understand performance. If you scored 43 out of 50, your percentage score is (43 ÷ 50) × 100 = 86%. Many grading systems work on percentage thresholds for letter grades.
Health and Nutrition
Daily value percentages on nutrition labels show what portion of your recommended daily intake a serving provides. A food with 15g of protein where the daily value is 50g provides (15 ÷ 50) × 100 = 30% of your daily protein.
Frequently Asked Questions
What is 20% of 300?
20% of 300 is 60. Calculated as 300 × 0.20 = 60.
What percentage is 12 out of 50?
12 out of 50 is 24%. Calculated as (12 ÷ 50) × 100 = 24%.
How do I calculate a 15% tip using percentages?
Find 10% of the bill by moving the decimal one place left, then add half of that for the remaining 5%. For a $60 bill: 10% = $6.00, half of that = $3.00, so 15% tip = $9.00.
What is the percentage increase from 50 to 75?
The percentage increase from 50 to 75 is 50%. Calculated as ((75 − 50) ÷ 50) × 100 = 50%.
How do I reverse a percentage increase?
To find the original value before a percentage increase, divide the new value by (1 + the percentage as a decimal). For example, if a price increased 25% to reach $125, the original was $125 ÷ 1.25 = $100.