See the answer. Understand the maths.
Choose a calculator, enter your numbers, and select Calculate. Your answer appears with the steps used to reach it. Each page also includes a formula, examples, and answers to common questions.
Transparent methods
Percentage tools use fractions out of 100. The average tool adds values and divides by their count. Date calculations use the Gregorian calendar and UTC date boundaries. Time duration uses minutes after midnight. Nothing relies on a prediction or an AI-generated answer.
Rounding and precision
Most results display up to 12 significant digits. Discounts display two decimal places. Calculations use JavaScript floating-point numbers, so they are approximate and are not a substitute for an exact-decimal accounting system. The displayed steps may be rounded separately from the underlying calculation.
Input limits
Numeric values must be finite and between −1 trillion and 1 trillion. The average calculator accepts up to 1,000 entries. Percentage change requires a positive starting value, and discounts must lie between 0% and 100%.
Private calculations
Calculations run on your device. We do not put input values into URLs, save them to browser storage, or send them to an API. The Copy resultbutton writes the result to your clipboard only when you select it.
Reproducible examples
The source includes automated tests for the formulas, invalid inputs, leap days, overnight periods, and generated pages. Each calculator presents worked examples so you can check its approach yourself.