Calculator Blog
Guides that explain the maths behind the tools — how percentages, compound interest, mortgages and more actually work.
How to Calculate Percentages: The Complete Guide
Learn how to calculate percentages by hand: percent of a number, percentage increase, percentage decrease and …
Read articleHow Compound Interest Works (and Why Time Matters)
Compound interest explained simply: the formula, how contributions grow it, the rule of 72, and why starting e…
Read articleHow to Calculate Your Age (Exactly)
How age is calculated in years, months and days: the birthday rule, leap years and month lengths, with example…
Read articleHow BMI Is Calculated (and What It Really Tells You)
How BMI is calculated in metric and imperial, the WHO categories, BMI prime, and the important limitations of …
Read articleHow Mortgage Payments Are Calculated
The mortgage payment formula explained: principal, interest, taxes and insurance (PITI), how amortization spli…
Read articleHow to Calculate ROI (Return on Investment)
ROI and CAGR explained: the formulas, worked examples, the difference between them, and how to compare investm…
Read articleHow to Calculate Loan Interest
How loan interest works: simple vs compound, monthly interest on balances, total interest over a term, and the…
Read articleHow to Calculate a Percentage Increase
The percentage increase formula, worked examples, the reverse calculation (finding the original value), and co…
Read articleHow to Calculate Monthly Payments on Any Loan
The amortization formula that powers every loan payment: worked examples for loans and mortgages, and how to u…
Read articleHow to Use a Scientific Calculator: A Practical Guide
How to use a scientific calculator: order of operations, trig in degrees and radians, powers and roots, logari…
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