Content Hub

Time & Date Guides

Deep-dive tutorials designed for long-tail questions, with links to calculators so you can apply each concept instantly.

2026-03-20 · 6 min read

How to Calculate Business Days in Excel

Learn practical formulas for counting workdays, skipping holidays, and avoiding common spreadsheet mistakes.

2026-03-20 · 5 min read

A clear explanation of ISO-8601 week rules, why week 1 can start in the prior year, and how to avoid reporting errors.

2026-03-20 · 7 min read

Understand Naegele’s rule, ultrasound adjustments, and why due dates are estimates—not exact delivery predictions.