Online calculators
Calculate percentages, dates and unit conversions locally, with your numbers and inputs kept in the browser.
Tools in this category
Pick a calculator for your question
- To recover a price before a discount, choose Percentage calculator and use the original amount calculation.
- When a form asks for age on a particular day, use Age calculator with that reference date.
- For a recipe using unfamiliar measurements, open Unit Converter and select the matching mass or volume units.
- To work with trigonometric functions or supported algebra operations, choose Scientific Calculator and check the relevant mode.
- When you need a set of numbers within chosen bounds, use Random number generator and configure the draw.
Inputs, formulas and interpretation
This collection brings together everyday arithmetic, calendar calculations, measurement conversion and scientific functions. Calculations run locally in your browser, so entered numbers and dates are not uploaded. Start by identifying what the input represents: a starting value, a reference date or a measurement with units. That choice matters as much as the figures themselves.
Displayed values may be rounded, and estimates should be read with their assumptions. Calendar age is different from elapsed clock time, while adult BMI is an indicator rather than a diagnosis. Unit conversion covers length, mass, temperature and volume. The scientific engine supports selected operations and requires its library to load before symbolic features become available.
Understanding your calculation
Why does my percentage result look wrong?
Check the base value and the operation. Percentage change uses a starting amount, while percentage points compare rates directly. A change from zero has no defined relative percentage, and display precision can hide small differences.
Does the age result include my exact birth time?
The calculator uses dates, without a birth time. Its hours and minutes come from calendar days, so they do not account for clock changes. Check the leap-day setting when a birthday falls on 29 February.
Can I use the BMI tool for a child?
The categories shown are intended for adults aged 18 and over, rather than children or pregnancy. The displayed weight interval comes from the formula and should not be treated as a personal target.
Do I need to pay for scientific functions?
The scientific calculator is free to use, alongside the simpler calculators. The site is supported by ads. Symbolic operations depend on the available engine and supported expressions, rather than a paid upgrade.