Calculate percentages instantly — find percent of a number, increase/decrease, and more
A percentage is a way of expressing a number as a fraction of 100. The percent sign (%) literally means "per hundred." So 25% means 25 out of 100, equivalent to the fraction 1/4 or the decimal 0.25. Percentages are used everywhere in daily life — calculating sales tax, restaurant tips, retail discounts, school grades, interest rates, statistics, and price changes. Even though the math is simple, doing it manually is error-prone, especially for percentage increase/decrease, markup calculations, and reverse percentages. The FileTools Percentage Calculator handles 6 different percentage operations in one tool, with instant results and no math required on your part.
Common use cases: calculating sales tax on a purchase; figuring out the tip at a restaurant; determining the discount on a sale item; calculating grades and test scores; computing markups on products in retail; finding interest on a loan or savings account; calculating percentage change in stock prices; figuring out commission on sales; computing growth rates for businesses or websites; determining nutritional values; checking percentage difference in scientific measurements; and any time you need to compare two numbers as a ratio of 100.
What is X% of Y: the most common calculation — find a percentage of a number. Useful for tip, tax, and discount calculations.
X is what % of Y: reverse calculation — given two numbers, what percentage is one of the other? Useful for grades, ratios, and statistics.
Percentage Increase: calculate growth between two values. Useful for price changes, sales growth, weight gain, or any positive change.
Percentage Decrease: calculate reduction between two values. Useful for discount analysis, weight loss, or any negative change.
Add X% to a number: apply markup or tax. Useful for retail pricing, sales tax, or service charges.
Subtract X% from a number: apply discount or deduction. Useful for sale prices, post-tax amounts, or net values after fees.
X% of Y = (X × Y) ÷ 100
X is what % of Y = (X ÷ Y) × 100
% Increase = ((New − Old) ÷ Old) × 100
% Decrease = ((Old − New) ÷ Old) × 100
Add X% = Y + (Y × X ÷ 100)
Subtract X% = Y − (Y × X ÷ 100)
1. Find the calculator that matches your need (6 cards above)
2. Enter your numbers in the input fields
3. Click "Calculate" to see the result
4. The result shows the answer plus a clear explanation
5. Use multiple calculators in parallel — each works independently
✅ 100% free — no signup, no ads in tool, no tracking
✅ 6 different percentage operations in one tool
✅ Clear explanation of each result
✅ Client-side only — your numbers never leave your device
✅ Handles decimals and large numbers
✅ Works on Windows, Mac, Linux, Android, iOS — any browser
✅ Works offline once page is loaded
To find X% of Y, multiply Y by X and divide by 100. For example, 25% of 200 is (25 × 200) ÷ 100 = 50. Use the "What is X% of Y" calculator at the top of this page to compute this instantly without doing the math yourself.
Percentage change = ((New value − Old value) ÷ Old value) × 100. If the result is positive, it's an increase; if negative, a decrease. For example, a price going from $100 to $150 is a 50% increase. Use the dedicated Percentage Increase or Percentage Decrease cards above to calculate automatically.
To add X% to a number Y: Y + (Y × X ÷ 100). For example, adding 20% tax to $200 gives $200 + $40 = $240. To subtract: Y − (Y × X ÷ 100). Useful for calculating sales tax, tips, discounts, or markups. Use the Add or Subtract cards above for instant results.
Percent (%) is the symbol used after a number — like 25%. Percentage refers to the concept itself or a quantity expressed as a fraction of 100. In casual use, the terms are interchangeable. Mathematically, 25% means 25 per 100, or 0.25 as a decimal, or 1/4 as a fraction.
No. All percentage calculations happen entirely in your browser using JavaScript — nothing is uploaded, logged, or stored. Your numbers stay private on your device. The calculator works offline once the page is loaded.
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