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, how to read the result, and the difference between percent change and percentage points.
- Percentage CalculatorFree multi-mode percentage calculator: percent of a number, what percent X is of Y, reverse percentage, percentage change, increase/decrease by a percent, decimal ↔ percent, and fraction → percent. Each answer shows the formula, the substituted equation, and step-by-step working.
- Percentage Increase CalculatorFree percentage increase calculator: find the percent growth from an old value to a new higher value, or the new value after a given increase. Formula, worked examples, and common mistakes.
- Percentage Decrease CalculatorFree percentage decrease calculator: find the percent drop from an old value to a new lower value, or the value after a given decrease. Formula, worked examples, and common mistakes.
- Discount CalculatorFree discount calculator: find the sale price and dollar savings from a percent-off deal, and see how stacked discounts really combine. Formula, worked examples, and a percent-off reference table.
- Sales Tax CalculatorFree sales tax calculator: add any sales tax rate to a price to get the tax amount and total, or reverse-calculate the pre-tax price from a total. Formula, worked examples, and a US rate reference.
- Tip CalculatorFree tip calculator: work out the tip amount, the total bill, and each person's share when splitting. Formula, worked examples, a US tipping reference, and answers on pre-tax vs post-tax tipping.
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.