Age in Days Weeks Months

The Age in Days Weeks Months tool turns a birth date into every unit you might want at once.

Enter the date someone was born and, optionally, the date to measure against — leave it blank to use today — and the tool returns an exact calendar age in years, months and days alongside the same span restated as total days, total weeks, total months and total hours lived.

Counting age purely in calendar terms is surprisingly fiddly because months have different lengths and leap years add a day.

This tool handles those edge cases the way people naturally count: it advances whole months from the birth date, clamps to the end of short months, then measures the leftover days, so a date like the 31st of January never produces a confusing negative day count.

The total-days figure, by contrast, is a straight difference in real elapsed time, which is exactly what you want for milestone counts.

It is handy for birthday milestones, working out a baby’s age in weeks, checking eligibility windows, or just satisfying curiosity about how many days you have been around.

Everything is calculated locally in your browser, so no birth dates are ever uploaded or stored, and it keeps working offline once the page has loaded.