TetraKits
Percentage Calculator
Solve three common percentage problems in one tool: what is X% of a number, what percent X is of Y, and percent increase or decrease between two values. Enter values and read results instantly.
Read: Percentage Calculator Guide: Discounts, Tax, Markup & More →
- 5 Calculation Modes
- Free to Use
- Instant Results
- Tip: 18% of a $85 bill = $15.30
- Discount: 25% off $120 = $90 (save $30)
- Grade: 42 out of 50 = 84%
- Growth: From $1,000 to $1,150 = +15% change
How to calculate percentages
- 1
Choose calculation type
Select % of (what is 20% of 80?), what % (15 is what % of 60?), or change (percent increase/decrease).
- 2
Enter your values
Type the numbers for your problem. Results update as you type.
- 3
Read the answer
See result with formula explanation. For sale pricing, use the discount calculator.
Why Use This Calculator?
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Free Forever
Run unlimited percentage calculations with no subscriptions.
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Five Modes
Cover percent-of, what-percent, increase, decrease, and change.
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Live Updates
Results update instantly as you type. Works on any device.
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Privacy Friendly
All math runs in your browser. Nothing is sent to a server.
Frequently Asked Questions
How do I find what percent one number is of another?
Select "what %" mode. Enter the part and the whole. Result = (part ÷ whole) × 100. Example: 15 of 60 = 25%.
How is percent increase calculated?
Percent change = ((new − old) ÷ old) × 100. A rise from 80 to 100 is a 25% increase.
Can I calculate X% of a number?
Yes. Select "% of" mode, enter the percentage and base number. 20% of 150 = 30.
What about negative percent change?
A decrease produces a negative percent change. Dropping from 100 to 80 is −20%.
Is this percentage calculator free?
Yes. Unlimited calculations with no signup.
Three Percent Problems, One Tool
Tips, tax rates, grade curves, and growth metrics phrase the same math three different ways. Switch modes to solve "X% of Y," "X is what % of Y," or percent change without relearning formulas.
Switch between calculation modes using the tabs at the top of the tool. Each mode shows a plain-language summary of the result so you know exactly what the numbers mean.
