Everyday

Work out what X% of Y is, what percentage X is of Y, or the percentage change between two numbers.

Work out your exact age in years, months and days, or your age as of any date.

Find the number of days, weeks, months and years between any two dates.

Convert between metric and imperial length units — mm, cm, m, km, inches, feet, yards and miles.

Convert between metric and imperial weight units — mg, g, kg, tonnes, ounces, pounds and stone.

Convert between Celsius, Fahrenheit and Kelvin.

Work out the tip on a bill, the total, and the amount per person when splitting.

Work out the sale price after a percentage discount, and how much you save.

Calculate your semester GPA from letter grades and credit hours, on the standard 4.0 scale.