Instant Percentage Calculator - Ask in Plain English
PercentMath lets you calculate percentages the way you naturally think about them. Type questions like "What is 15% of 200?" and get instant, accurate results - no formulas or setup required.
Use it for discounts, grades, taxes, financial comparisons, or quick math checks. Prefer structured inputs? The calculators below cover percentage, percent-of, and percentage change.
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Calculate Percentage
Find What Percent
Percentage Change
How to Use the Percentage Calculator
Calculate Percentage
Use this calculator when you need to find what a percentage of a number is. For example, "What is 25% of 80?" Simply enter 25 in the first field and 80 in the second field. The calculator instantly shows you that 25% of 80 equals 20.
Common uses: Calculating discounts, finding tip amounts, determining sales tax, or figuring out what portion of a budget to allocate.
Find What Percent
This calculator helps you determine what percentage one number is of another. For example, "30 is what percent of 120?" Enter 30 in the first field and 120 in the second field to find that 30 is 25% of 120.
Common uses: Calculating test scores, determining completion rates, finding what percentage of a goal you've achieved, or comparing values.
Percentage Change
Use this calculator to find the percentage increase or decrease between two numbers. For example, if a price increased from $50 to $65, enter 50 as the starting value and 65 as the ending value. The calculator shows a 30% increase.
Common uses: Calculating salary increases, tracking stock price changes, measuring sales growth, or determining price changes over time.
Understanding Percentage Calculations
What is a Percentage?
A percentage is a way of expressing a number as a fraction of 100. The word "percent" literally means "per hundred." For example, 50% means 50 out of 100, or one half. Percentages make it easy to compare values and understand proportions.
Basic Percentage Formulas
- Find percentage of a number: (Percentage ÷ 100) × Number
- Find what percent: (Part ÷ Whole) × 100
- Percentage change: ((New Value - Old Value) ÷ Old Value) × 100
Real-World Examples
Example 1: Shopping Discount
A shirt costs $40 and is on sale for 25% off. How much do you save?
Solution: 25% of $40 = (25 ÷ 100) × 40 = $10
You save $10, so the sale price is $30.
Example 2: Test Score
You answered 42 questions correctly out of 50 total questions. What's your percentage score?
Solution: (42 ÷ 50) × 100 = 84%
Your test score is 84%.
Example 3: Salary Increase
Your salary increased from $45,000 to $49,500. What's the percentage increase?
Solution: (($49,500 - $45,000) ÷ $45,000) × 100 = 10%
Your salary increased by 10%.
Why Use PercentMath?
- Fast Results: Get instant calculations as you type - no button pressing required
- Natural Language: Type questions naturally like "what is 15% of 80" and get immediate answers
- Ad-Free Experience: Clean, distraction-free interface with no annoying advertisements
- Mobile Friendly: Works perfectly on phones, tablets, and computers
- Copy Results: One-click copy button to paste results anywhere you need them
- Shows Formulas: Learn the math behind the calculations for educational value
- Always Free: No signup, no subscription, no hidden fees - completely free forever
Frequently Asked Questions
How do I calculate what percentage one number is of another?
Divide the first number by the second number, then multiply by 100. For example, to find what percent 30 is of 120: (30 ÷ 120) × 100 = 25%. Use our "Find What Percent" calculator above for instant results.
How do I calculate a percentage increase?
Subtract the original number from the new number, divide by the original number, and multiply by 100. For example, an increase from 50 to 75: ((75 - 50) ÷ 50) × 100 = 50%. Use our "Percentage Change" calculator for automatic calculations.
What's the difference between percentage and percentage points?
Percentage points measure the arithmetic difference between two percentages. If something increases from 20% to 30%, that's a 10 percentage point increase, but a 50% relative increase (because 10 is 50% of 20).
Can I use this calculator for negative percentages?
Yes! The percentage change calculator automatically detects whether there's an increase or decrease. If the final value is less than the starting value, it will show a percentage decrease.
How accurate are the calculations?
All calculations are performed using standard mathematical formulas and are accurate to two decimal places. The calculator uses JavaScript to perform calculations instantly in your browser.