Percentage & Everyday Math Calculators
These calculators handle the percentage and arithmetic problems that come up in ordinary life — splitting a bill, checking a sale price, adding sales tax, or figuring out how much a number has grown or shrunk. Each one shows the underlying formula so the answer is never a black box, and each includes examples you can follow step by step.
- Percent Change CalculatorCalculate the percentage change between two values. Free calculator showing the formula, worked examples, and the difference between percent increase and decrease.
- Percentage CalculatorCalculate what percentage one number is of another. Free calculator with the formula, worked examples, and common use cases.
- Percentage Increase CalculatorCalculate the percentage increase from an old value to a new higher value. Free calculator with formula and examples.
- Percentage Decrease CalculatorCalculate the percentage decrease from an old value to a new lower value. Free calculator with formula and worked examples.
- Discount CalculatorCalculate the sale price and dollar savings after a percentage discount. Free calculator with formula and examples.
- Sales Tax CalculatorCalculate the final price of an item after adding sales tax. Free calculator with formula and worked examples.
- Tip CalculatorCalculate the tip amount, total bill, and per-person share. Free calculator with formula and worked examples.
Percentages in Plain English
A percentage is just a fraction out of 100. To find a percentage of a number, convert the percent to a decimal (divide by 100) and multiply. For example, 20% of 80 is 0.20 × 80 = 16. The Percentage Calculator handles the most common forms of this question, including "what percent is X of Y" and "X is what percent of Y."
Increase, Decrease, and Change
Percentage increase and decrease describe how much a value goes up or down relative to its starting point, while percent change is the general version that can be positive or negative. The formula is the difference divided by the original value, times 100. These tools are useful for tracking price moves, measuring growth, or comparing before-and-after figures. Try the Percent Change, Percentage Increase, and Percentage Decrease calculators.
Shopping and Dining Math
Three of the most-used everyday tools live here: the Discount Calculator tells you the sale price and how much you save, the Sales Tax Calculator adds tax at any rate, and the Tip Calculator works out a gratuity and can split it across a group. Together they cover the percentage math behind almost every purchase.
All calculators provide estimates for educational purposes only. See our Financial Disclaimer and Methodology.