ToolHQ Blog
Guides, tutorials, and tips for getting the most out of free online tools. 81 articles.
81 articles — page 4 of 4
James and Marta Borrowed $320,000. The Total Cost Is $728,000. Here Is Why.
Mortgage amortization front-loads interest so you barely reduce your balance in the first decade. Here's how the math works and what prepayment actually saves you.
The 1832 Equation That Calls Healthy Athletes Obese
BMI was invented in 1832 for population statistics, not health assessment. Here is the history behind the formula your doctor uses, and why it fails athletes.
John Warnock Wrote Six Pages in 1990 Describing a Problem. The Solution Became the PDF.
Adobe's John Warnock wrote the Camelot Project paper in 1990 to solve document fidelity across systems. Here is how that paper became the PDF and why Word-to-PDF conversion matters.
Most Word Count Rules Are Invented. Here Is What Word Count Actually Measures.
SEO word count minimums, NaNoWriMo targets, and academic length requirements are mostly arbitrary. Here's what word count genuinely predicts and when it matters.
She Said Yes to 'Pay in Dollars' at the ATM. Here Is What That Cost Her.
ATMs and merchants abroad offer to charge you in your home currency. This convenience costs 3-13% extra. Here is how dynamic currency conversion works.
What JPEG Throws Away (And Why PNG Can't Give It Back)
Most people think converting JPEG to PNG improves image quality. It doesn't. PNG preserves the data JPEG already destroyed. Here's what actually happens.
The $327 Million Unit Conversion Mistake That Destroyed a Mars Mission
In 1999 NASA lost a $327M spacecraft because one team used pound-force seconds and another expected newton-seconds. Here's what the error teaches about unit conversion.
Marcus and Priya Borrowed $304,000. They Found Out the Total Cost Six Months After Closing.
A $304,000 mortgage at 6.5% costs $387,920 in interest over 30 years. Here's what amortization schedules reveal, and why the ratio of interest to principal matters.
Why PDF-to-Word Conversion Never Looks Quite Right (and What You Can Do About It)
PDF-to-Word conversion fails on complex layouts because PDF discards document structure. Here's what PDF actually stores, why conversion is hard, and when it works.