Guides & explainers
The reasoning behind the tools. How percentages actually work, what a loan really costs, why BMI misleads, and how to pick a password that holds up. Written to answer the question, then get out of the way.
How to Choose a Password That Actually Holds Up
Most password advice is twenty years out of date and made things worse. Here's what genuinely protects an account, in the order that matters.
August 26, 2026 · The Day to Day Tools Team
BMI: What the Number Means and What It Definitely Doesn't
BMI was invented in the 1830s to describe populations, not people. Here's what it's genuinely useful for, where it fails, and what to measure instead.
MoneyWhat a Loan Actually Costs (And Why the Monthly Payment Hides It)
Lenders quote the monthly payment because it's the smallest number they can show you. Here's how to see the real cost of borrowing before you sign.
Everyday MathsHow to Calculate Percentages Without Reaching for a Calculator
The four percentage questions that cover almost every real situation, the mental shortcuts that make them fast, and the three mistakes that cost people money.