Guides
Deeper explanations for topics covered by our calculators and converters. Each guide links back to a free tool you can use right away.
What Is BMI? Body Mass Index Explained
Body mass index (BMI) is a simple ratio of weight to height used as a population-level screening tool. It helps estimate whether an adult's weight may fall outside a commonly referenced healthy range. BMI does not measure body fat directly, but decades of epidemiological research link BMI ranges to health outcomes at the population level. For individuals, BMI is best treated as one data point among many—not a diagnosis on its own.
Includes BMI Calculator
BMI Cutoffs and WHO Categories
WHO adult BMI cutoffs split weight-for-height into underweight (below 18.5), normal (18.5–24.9), overweight (25.0–29.9), and obesity (30.0 and above). Obesity is further split into Class I, II, and III. The table below is the screening chart most clinical guidelines cite. Cutoffs are population tools, not diagnoses—use the calculator, then read the limitations before treating a single number as a verdict.
Includes BMI Calculator
Understanding Cap Rate in Real Estate
Capitalization rate (cap rate) expresses a property's net operating income as a percentage of its value. Investors use it to compare yields across deals before diving into financing details. Cap rate answers a simple question: if I bought this property all-cash, what annual return would operating income represent relative to price? It is one of the first metrics every rental investor should understand.
Includes Cap Rate Calculator
TDEE and Calorie Deficits Explained
Total daily energy expenditure (TDEE) is an estimate of how many calories you burn per day including activity. Weight loss typically requires eating below TDEE; maintenance matches it. Understanding how TDEE is calculated—and how to apply a deficit safely—turns abstract calorie numbers into a practical daily target you can actually follow.
Includes Calorie Calculator
JSON to CSV for Excel
Excel and Google Sheets import CSV easily, but JSON is hierarchical. Converting JSON to CSV flattens records into rows and columns suitable for spreadsheet analysis. This guide covers when and how to flatten nested structures, avoid encoding problems, and import cleanly into Excel without mangled dates, broken special characters, or misaligned columns.
Includes JSON to CSV Converter Pro
Rental Deal Analysis Basics
Rental deal analysis combines income, expenses, and financing to estimate whether a property meets your return targets. Start with simple metrics, then layer in leverage. This guide walks through the recommended screening order, explains each metric's role, and provides a complete numeric example you can replicate for any listing.
Includes Rental Property Deal Analyzer
Rental Property Analysis Step by Step
Analyzing a rental property step by step turns an overwhelming pile of numbers into a repeatable process. This guide walks through a complete underwriting example—from verifying rent and expenses through financing assumptions to final return metrics—so you can evaluate any deal with confidence and know exactly when to walk away.
Includes Rental Property Deal Analyzer
Mortgage Amortization Explained
Amortization is the process of paying off a loan through scheduled payments that include both principal and interest. The split changes every month over the loan term. Understanding amortization helps you compare loan offers, decide between 15- and 30-year terms, plan extra principal payments, and see how much of your housing cost actually builds equity versus paying the lender.
Includes Mortgage Calculator with Amortization
Client-Side PDF Processing
Client-side PDF tools process files entirely in your browser. Nothing uploads to a server—ideal for contracts, medical records, tax documents, and confidential business files. This guide explains how local PDF processing works, its privacy advantages, browser limitations, and step-by-step workflows for merging and splitting documents.
Includes PDF Merge Pro
How to Add a Favicon in HTML
A favicon is the small icon in browser tabs, bookmarks, and some search results. You need two pieces: the image files, and HTML that points to them. Place favicon.ico at the site root for older clients, then add explicit link tags for PNG and Apple touch icons so modern browsers do not guess.
Includes Favicon Generator
SQL Formatting Best Practices
Consistent SQL formatting speeds code review and reduces mistakes when editing long queries copied from logs or BI tools.
Includes SQL Formatter
How to Compare Text Diffs
Diffing helps review contract edits, changelog entries, and pasted copy updates before publishing.
Includes Text Diff Tool