Calculators
Small calculators for questions that come up while studying, shopping, or pricing work. Each one shows the inputs and the result in the same place, so you can change a number and see what moves.
Percentage calculator
Find a percent of a number, a share of a total, or a percent increase and decrease.
Age calculator
Calculate age in years, months, and days from a date of birth.
BMI calculator
Calculate body mass index from height and weight, with WHO adult categories.
Discount calculator
See the sale price and the amount saved after a percent off.
Compound interest calculator
Project a lump sum with yearly, quarterly, or monthly compounding.
CAGR calculator
Find the compound annual growth rate between a start value and an end value.
Date difference calculator
Count the days, weeks, and weekdays between two dates.
Profit margin calculator
Turn cost and selling price into profit, margin, and markup.