Blog & Guides
In-depth explainers on developer tools, calculators, and online utilities. Learn the math and code behind 696+ free tools.
10 articles in calculator
Unit Price Calculator — Find the Best Deal Per Unit Instantly
Compare prices per unit, per kg, per litre or per item with our free unit price calculator. Find which pack size is the best value — works for groceries, bulk buying and more.
How to Make Random Teams Online — Fair, Fast, and Free
Stop arguing about who picks teams. Use a random team generator to split any group into balanced, unbiased teams in seconds — no signup needed.
How to Calculate BMI: Formula, Ranges, and Limitations
The complete guide to Body Mass Index — the formula, WHO ranges, what BMI actually tells you, and its well-known limitations.
How Mortgage Payments Are Calculated: The Math Behind Your Monthly Bill
Understand the amortization formula, how your payment splits between principal and interest, and how extra payments can save you thousands.
Compound Interest Explained: The Most Powerful Force in Finance
How compound interest works, the formula, compounding frequencies, the Rule of 72, and why it matters for both savings and debt.
Percentage Calculations: The Complete Guide with Formulas
Master every type of percentage calculation — basic percentages, percentage change, working backwards, and real-world examples for discounts, tax, and grades.
How Currency Exchange Rates Work: A Plain-English Guide
Understand spot rates, bid/ask spreads, what moves exchange rates, and how to get the best rate when converting currency for travel or business.
Understanding TDEE and Macros: How to Calculate Your Daily Calorie Needs
A complete guide to calculating your TDEE (Total Daily Energy Expenditure) and macros — the Mifflin-St Jeor formula, activity multipliers, and practical nutrition planning.
How EMI Is Calculated: Understanding Your Loan Repayment
A complete guide to EMI calculation — the formula, flat rate vs reducing balance, how tenure affects total interest, and prepayment benefits.
How to Calculate ROI: Formulas, Examples, and Common Mistakes
Master ROI calculation — the basic formula, annualized ROI, what counts as costs and gains, and how ROI compares to IRR and NPV.