Guides, Tutorials & Tips

Learn how to use a word counter to track words, characters, sentences, paragraphs and reading time — plus a complete reference of character limits for every major platform.

Learn how QR codes work, which content type to use for each situation, how error correction levels affect scanability, and how to generate a free QR code for any purpose — no sign-up required.

Learn the BMI formula for metric and imperial units, the WHO weight categories, and the well-documented limitations of BMI as a health screening measure — free, instant calculator.

Learn how age is actually calculated, the leap year rule and how it affects February 29 birthdays, calendar vs full-day calculation methods, and practical uses beyond birthdays — free, instant tool.