Age Calculator
Calculate your exact age in years, months, and days. Find the time between any two dates.
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What Is a Age Calculator?
An age calculator converts a date of birth into an exact age broken down by years, months, and days. Enter any birth date and receive the precise elapsed time to today or to a date you choose.
Manual age counting often goes wrong around month boundaries and leap years. This tool handles 28-, 29-, 30-, and 31-day months automatically. It also outputs the total in days, weeks, and months for quick reference.
Use it to verify ages for official forms, track milestones, or settle birthday debates. The result updates instantly whenever you change either date.
How Do You Use This Age Calculator?
Enter your date of birth (or any start date). Optionally enter a second date (defaults to today). Click Calculate to see the exact age in years, months, and days.
- Select your date of birth from the date picker.
- Leave the second date as today or pick a custom end date.
- Press Calculate to generate the result.
- Read the age in years, months, and days at the top of the output.
- Check the additional breakdown for total days, weeks, and months.
- Change either date to recalculate instantly.
How Does the Age Calculator Formula Work?
The formula used: Age = Current Date - Date of Birth (adjusted for month/day boundaries)
The calculator counts complete years first. It subtracts the birth year from the end year and reduces by 1 if the birthday has not yet occurred in the end year.
Next it counts complete months from the last birthday. Finally it counts remaining days. The formula adjusts for varying month lengths: Age = (end year - birth year) adjusted by whether (end month, end day) >= (birth month, birth day).
Leap years are included in the day total. February 29 birthdays are handled by rolling to 1 March in non-leap years.
What Are Some Example Calculations?
Born on 15 March 1990, as of 25 February 2026: Age = 35 years, 11 months, 10 days. Total days = 13,097.
Child born on 1 June 2020 (age today, 26 Feb 2026)
2026 - 2020 = 6 full years. June to Feb = 8 months. 1 Jun to 26 Feb leftover = 25 days.
5 years, 8 months, 25 days (2,097 total days).
Leap-year birthday: 29 February 2000 to 1 March 2025
2025 - 2000 = 25 years. Feb 29 to Mar 1 in a non-leap year = 1 extra day.
25 years, 0 months, 1 day (9,132 total days).
Time between two historic dates: 1 Jan 1900 to 1 Jan 2000
Straight 100-year span. Includes 24 leap years in that window.
100 years, 0 months, 0 days (36,524 total days).
When Should You Use a Age Calculator?
Use this calculator whenever an exact age is required. Common situations include filling in passport or visa applications, verifying school enrollment cut-off dates, and confirming retirement eligibility.
It also helps parents track infant milestones by week or month. Event planners use it to count days until a birthday or anniversary. Any scenario where you need the precise gap between two dates benefits from this tool.
What Do These Terms Mean?
What Are the Best Tips to Know?
- Double-check the birth year if the result looks wrong by exactly one year.
- Use the custom end-date field to calculate age at a future or past event.
- Copy the total-days figure directly into spreadsheets for further calculations.
- Bookmark the page with your birth date in the URL for instant daily updates.
- Switch to the date calculator if you need to add or subtract a fixed number of days.
What Mistakes Should You Avoid?
- Entering the month and day in the wrong order (DD/MM vs MM/DD).
- Forgetting that someone born on 29 February does not turn a year older on 28 February.
- Counting the start date and end date as two separate days when only one boundary should be counted.
- Assuming every year has 365 days when calculating total days manually.
Frequently Asked Questions
How is exact age calculated?
Exact age is calculated by counting complete years, then complete months, then remaining days from your date of birth to the target date.
Does this account for leap years?
Yes. The calculator accounts for leap years and varying month lengths when determining the exact number of days.
Can I calculate the difference between two dates?
Yes. Enter any start date and end date to calculate the time between them in years, months, and days.
How do I calculate my age in months only?
Multiply the years in the result by 12 and add the remaining months. For example, 35 years and 4 months equals 424 months. The total is shown in the detailed breakdown.
What happens if I enter a future date as the birth date?
The calculator still returns the time gap between the two dates. The result represents a countdown rather than an elapsed age.
Is the calculator accurate for historical dates before 1900?
Yes. The calculation follows the Gregorian calendar rules for any date. Accuracy depends on whether the country used the Gregorian calendar at that time.
Can I use this to find the age of a building or object?
Enter the construction or manufacture date as the start date. The result shows the elapsed time in years, months, and days, which works for any object.
Why does my age in days differ from a simple 365-times-years multiplication?
Leap years add extra days. Over 40 years roughly 10 leap days accumulate. The calculator counts actual calendar days rather than estimating from a fixed 365-day year.
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