Percentage Calculator
Quickly calculate percentages, find what percent one number is of another, or compute percentage increases and decreases.
About This Calculator
The Percentage Calculator offers three essential modes: finding what X% of Y is, determining what percentage X is of Y, and computing the percentage change between two values (increase or decrease). Percentages are fundamental in everyday life — from calculating tips and discounts to understanding financial returns and grade scores.
How to Use
- Enter your values in the input fields above
- Click the calculate button to see results
- Review your results displayed below the inputs
- Use the reset button to clear all fields and start over
The Formula
How the calculation works under the hood
Percent of a number
Used when you want a portion of a number — tips, discounts, sales tax, commissions.
What percent is X of Y
Used for scores, share of budget, completion rates, and ratios expressed as percentages.
Percent change
Used to measure growth or shrinkage — price changes, investment returns, demographic shifts.
Worked Example
Step-by-step walkthrough with real numbers
“A shirt originally priced at $80 is now on sale for $60. What percent discount is that?”
- 1Old value = 80, new value = 60.
- 2Difference = 60 - 80 = -20.
- 3Divide by old value: -20 / 80 = -0.25.
- 4Multiply by 100: -25%.
The shirt is 25% off.
⚠️Common Mistakes
- ✕Forgetting to divide by 100 when using a percentage as a multiplier — 15% is 0.15, not 15.
- ✕Reversing percentages by simply adding the discount back (a $60 shirt after 20% off is NOT $72 originally — it is $75, because 60 / 0.80 = 75).
- ✕Confusing percentage points with percent change (going from 5% to 6% is a 1 percentage point increase but a 20% relative increase).
💡Pro Tips
- ✓Move the decimal one place left to find 10% of anything instantly.
- ✓Halve 10% to get 5% and combine for tips and quick estimates (15% = 10% + 5%).
- ✓When reversing a percentage discount, divide by 1 minus the discount rate, never subtract.
Related Guides
Go deeper with these in-depth articles
Percentage Calculations Made Simple
Every percentage problem solved by one of three formulas. Learn them once, add a couple of mental-math shortcuts, and you will never be stumped by a discount tag again.
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Read guide →How to Add and Subtract Fractions (Step-by-Step)
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Read guide →How to Budget Using the 50/30/20 Rule
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Read guide →How to Calculate Sales Tax in Any US State
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Read guide →How GPA Is Calculated: High School and College
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Read guide →How to Split a Bill and Tip Fairly
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Read guide →How to Use the Discount Formula for Shopping Deals
The discount formula explained for every deal type — percentage off, stacked coupons, BOGO, and rebates — with mental math shortcuts and worked examples.
Read guide →How to Add, Subtract, Multiply, and Divide Fractions
Step-by-step rules for every fraction operation — common denominators, cross-multiplication, reciprocals — with worked examples and simplification tips.
Read guide →Understanding Currency Exchange Rates for Travellers
How exchange rates work, where travellers get the best rates, hidden fees at airports and banks, and quick mental conversion tricks for any currency.
Read guide →Mental Math Tricks for Everyday Calculations
Ten mental math techniques for tips, discounts, multiplication, division, and quick estimation — with worked examples and practice tips.
Read guide →How to Calculate Electricity Costs for Home Appliances
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Read guide →Frequently Asked Questions
What is the "X% of Y" mode?
This mode calculates a specific percentage of a given number. For example, 15% of 200 equals 30.
How does the "X is what % of Y" mode work?
Enter two numbers and the calculator tells you what percentage the first number is of the second. For example, 50 is 25% of 200.
What does "% Change" calculate?
It computes the percentage increase or decrease from the original value to the new value. For example, going from 100 to 125 is a 25% increase.
Is this calculator free to use?
Yes! All calculators on Get Precision Calculator are completely free with no limitations or sign-up required.
Is my data saved or tracked?
No. All calculations are performed locally in your web browser. Get Precision Calculator does not store, collect, or track your calculation data.
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