TetraKits
Percentage Calculator
Quick percentage math for discounts, tips, markups, growth rates, and everyday calculations.
- 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
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 X percent of a number?
Select % of Number, enter the percentage and the base value. The result is the base multiplied by the percentage divided by 100. For example, 20% of 150 is 30.
How do I calculate a percentage increase?
Use the Increase mode. Enter the original value and the percentage to add. The calculator shows the new value and the amount added.
How is percent change calculated?
Percent change is ((new value − original value) ÷ original value) × 100. Use the % Change mode and enter both values.
Is this calculator free?
Yes. TetraKits Percentage Calculator is completely free with no signup, subscriptions, or usage limits.
Everyday Percentage Math Made Simple
Percentages appear everywhere: sale discounts, restaurant tips, exam scores, tax rates, and business markups. This calculator handles the most common scenarios so you get accurate answers in seconds without mental math or spreadsheets.
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.
