Short, practical explanations of date and age questions. Every example is calculated by the same engine as our tools.
Practical steps with a worked example, and when to use the calculator.
Read articleThe 11-day gap and how it adds up over a lifetime.
Read articleSaudi Arabia’s civil calendar and how it relates to moon sighting.
Read articleThe twelve month names, their lengths and the sacred months.
Read articleAn approximate conversion formula, its limits and an example.
Read articleThe leap-year rule and how 29 February birthdays are counted.
Read articleCounting the start and end dates, and common mistakes.
Read articleThe Friday–Saturday weekend and how to count working days.
Read articleFrom the Julian calendar to the 1582 reform.
Read articleService length in years, months and days, and common mistakes.
Read articleHow to work out a baby’s age in weeks and months, with examples.
Read articleThe origin of the day names and the old Arabic names.
Read articleThese articles answer the questions that come up when you use age and date tools: why Hijri and Gregorian ages differ, how Umm al-Qura works, whether to count the end date. Each explains the idea, works through real numbers, and points to the right tool.
Every number in the examples is re-checked automatically against the calculation engine on each site update, so the articles cannot drift from the tools. If you spot something, please contact us.
Last updated: