Percentage Calculator
Calculate percentages, discounts, and percent differences instantly
What is X% of Y?
Result
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Discount Calculator
Discount Amount: -
Final Price: -
Percent Difference
Percent Difference
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What Can a Percentage Calculator Do?
Percentage math shows up constantly — a discount at checkout, a tip, a grade, a year-over-year change — and it's easy to make a small arithmetic slip doing it in your head. This calculator covers the three most common cases: finding a percentage of a number, calculating a discount, and finding the percent difference between two values.
Enter your numbers and get an instant, accurate result — no formula to remember.
Why Use This Percentage Calculator
🧮 Three Calculators in One
Basic percentage, discount price, and percent difference — no need to remember three separate formulas.
⚡ Instant, Live Results
Results update as you type, so you can quickly try different numbers.
🆓 Always Free
Use it as many times as you need, with no signup.
How to Calculate a Percentage
- Basic percentage: enter the Percentage and Number to find, for example, what 15% of 240 is.
- Discount price: enter the Original Price and Discount percentage to see the final price after markdown.
- Percent difference: enter a First Value and Second Value to find how much one changed relative to the other.
Percentage Math Worth Knowing
1. "Percent of" vs. "percent difference" aren't the same
Finding 20% of $100 ($20) is a different calculation from asking how much a price changed by percent — mixing these up is one of the most common percentage mistakes.
2. Stacked discounts don't add up the way you'd expect
Two separate 10% discounts don't equal a flat 20% off — they compound, resulting in a slightly smaller total discount (19%) than adding the percentages directly.
3. Percent change direction matters
A 50% increase followed by a 50% decrease doesn't return you to the original number — the base value changes between the two calculations, so the two 50%'s apply to different amounts.
Frequently Asked Questions (FAQ)
Q: How do I calculate a discount price manually?
A: Multiply the original price by (1 − discount ÷ 100). For example, $80 with a 25% discount: 80 × (1 − 0.25) = $60.
Q: What's the formula for percent difference?
A: (New Value − Old Value) ÷ Old Value × 100. A positive result is an increase; negative is a decrease.
Q: Can I calculate reverse percentages, like finding the original price before a discount?
A: Yes conceptually — if you know the discounted price and the discount percentage, divide the discounted price by (1 − discount ÷ 100) to recover the original price.