Guides
Clear, practical explainers that go beyond the numbers — each one paired with the calculators to put it into practice.
Start here — in-depth guides
- Health · Guide The Complete Guide to Healthy Weight How BMI, body fat, BMR and calories fit together — a practical, no-fads framework for reaching and maintaining a healthy weight, backed by the numbers. Read guide →
- Finance · Guide How Loans and Interest Really Work A complete, jargon-free guide to borrowing — interest vs. APR, simple vs. compound, amortization, the main loan types, and how to pay less over the life of a loan. Read guide →
- Finance · Guide Investing for Beginners: Make Your Money Grow A plain-English starter guide to investing — why compounding matters, how to think about risk, what to actually invest in, and how to begin with any budget. Read guide →
- Finance · Guide Rent vs. Buy a Home: How to Decide A complete framework for the rent-or-buy decision — the true costs of each, the break-even horizon, opportunity cost, and how to run your own numbers. Read guide →
More guides
- Health BMI, BMR and Calories, Explained What BMI, BMR and TDEE actually mean, how they relate to each other, and how to use them together to set realistic, healthy goals — with calculators built in. Jul 17, 2026
- Finance How Much House Can You Afford? A practical, plain-English guide to figuring out a home price you can comfortably afford — using the 28/36 rule, down payments and the true cost of a mortgage. Jul 17, 2026
- Finance Compound Interest: How Your Money Grows Understand compound interest in plain English — how it works, why time matters more than timing, and how regular contributions turn small savings into large balances. Aug 30, 2026
- Finance How VAT Works: Adding It, Removing It, and Getting It Right Add VAT to a net price, strip it back out of a gross one, and understand why you divide rather than subtract — with the rate rules that catch people out. Aug 30, 2026
- Health Body Fat Percentage: What's Healthy? Why body fat percentage beats the scale, what a healthy range looks like for men and women, how to measure it at home, and how to lower it sustainably. Jul 17, 2026
- Everyday Calculating Days Between Dates How to count the days between two dates and add or subtract days for deadlines and due dates — with the leap-year and month-length details handled for you. Jul 17, 2026
- Finance Getting the Best Auto Loan How car financing really works — the true cost beyond the sticker price, why loan term matters so much, and how down payments and trade-ins change the math. Aug 30, 2026
- Health What's a Healthy Weight for Your Height? Ideal-weight formulas, what they really tell you, and why a healthy weight is a range — not a single number on the scale. Jul 17, 2026
- Health How Much Protein Do You Really Need? Daily protein targets for everyone from desk workers to lifters, why protein matters, and how to hit your number with everyday foods. Jul 17, 2026
- Everyday How to Calculate Hours Worked Turn clock-in and clock-out times into hours and decimal hours for payroll — including breaks and overnight shifts — without the arithmetic headaches. Jul 17, 2026
- Math How to Calculate Percentages (The Easy Way) Master the three percentage questions that cover almost every real-life situation — percent of a number, one number as a percent of another, and percent change. Aug 30, 2026
- Finance How to Calculate Sales Tax Add sales tax to a price or back it out of a total, understand how rates work, and avoid the rounding mistakes that trip up expense reports. Aug 30, 2026
- Everyday How to Calculate Your Exact Age Working out an exact age in years, months and days is trickier than it looks — here's why leap years and month lengths matter, and how to get it right every time. Jul 17, 2026
- Everyday How to Create a Strong Password What actually makes a password strong, why length beats complexity, and how to generate and manage passwords you never have to remember. Aug 30, 2026
- Math How to Use a Scientific Calculator A friendly tour of the scientific calculator — trigonometry, logarithms, powers, roots, factorials and constants — with worked examples you can follow along. Jul 17, 2026
- Math Working With Fractions: A Clear Guide Add, subtract, multiply and divide fractions with confidence — the rules, why they work, and how to simplify and convert to mixed numbers and decimals. Aug 30, 2026
- Finance Simple Interest Explained What simple interest is, the formula behind it, where you'll encounter it, and how it differs from the compound interest that grows savings. Jul 17, 2026
- Math Standard Deviation Explained What standard deviation actually measures, the difference between sample and population, and how to calculate it step by step — with a calculator built in. Aug 30, 2026