Guides
Step-by-step explanations of common calculations, with worked examples and links to the matching calculators.
How to Calculate BMI
Learn how to calculate body mass index (BMI) using the metric or imperial formula, understand what your result means, and see a worked example.
How to Calculate Percentage Change
Learn the percentage change formula, see worked examples of increases and decreases, and understand the difference between percentage change and percentage points.
How to Calculate a Mortgage Payment
Learn how monthly mortgage payments are calculated, what's included in the payment, and how interest rate and loan term affect your total cost.
How to Calculate Days Between Dates
Learn how to count the number of days between two dates, the difference between calendar days and business days, and how to add or subtract days from a date.