“How old will I be on this date?” or “exactly how many days old am I?” are harder to answer by hand than they look, once you account for varying month lengths and leap years. This tool gives you the exact breakdown instantly.
What Is the Age Calculator?
Enter a date of birth and (optionally) a different “as of” date, and get an exact years/months/days age breakdown, plus total months, total weeks, total days lived, and the number of days until the next birthday.
How to Use It
- Open the tool at /tools/age-calculator.
- Enter the date of birth.
- Leave “as of date” as today, or set it to any other date to calculate age at that point in time.
- Read the exact age breakdown and the supporting stats below it.
Key Features
- Correct calendar-aware math, borrowing real days/months from the actual calendar rather than approximating with fixed 30-day months.
- Custom “as of” date, for calculating age on a past or future date, not just today.
- Total months, weeks, and days lived, alongside the standard years/months/days breakdown.
- Days until next birthday, correctly rolling over to next year once this year’s birthday has passed.
When to Use This Tool
- Checking eligibility for age-restricted forms, contracts, or events on a specific date.
- Satisfying curiosity about exactly how many days you (or someone else) have been alive.
- Planning around an upcoming birthday, knowing exactly how many days remain.
Try It Now
Open Age Calculator directly, or press ⌘K and type the tool name from anywhere on the site.
Part of the Date & Time collection on WebdevToolbox — free, browser-based developer tools with no login required.