Time Tools

Date Difference Calculator

Calculate the exact difference between two dates in years, months, days, weeks, and hours. Also works as an age calculator.

Your data never leaves your browser — nothing is sent to any server.

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Years

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Months

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Days

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Total days

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Weeks

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Hours

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Business days

How to use
  1. 1

    Choose a mode

    Select Date Difference to compare two dates, Age Calculator to find your exact age, or Add / Subtract to offset a date by a number of days.

  2. 2

    Enter your dates

    Use the date pickers to select start and end dates. For age calculation, just enter your birth date.

  3. 3

    Read the results

    See the breakdown in years, months, and days, plus totals in days, weeks, hours, and business days.

  4. 4

    Copy the result

    Click 'Copy result' to copy a summary text to your clipboard for use in documents, emails, or messages.

FAQ (6)
How do I calculate the number of days between two dates?

Enter a start date and an end date in the Date Difference tab. The calculator instantly shows the exact difference in years, months, and days, along with the total number of days, weeks, hours, and business days between the two dates.

Can I use this as an age calculator?

Yes. Switch to the Age Calculator tab and enter your date of birth. The tool calculates your exact age in years, months, and days from your birth date to today. It updates automatically to always show your current age.

What are business days?

Business days (or working days) are Monday through Friday, excluding Saturday and Sunday. The calculator counts only weekdays between the two dates. Note that public holidays are not excluded as they vary by country and region.

Can I add or subtract days from a date?

Yes. Use the Add / Subtract tab. Enter a starting date and the number of days to add (use negative numbers to subtract). The tool shows the resulting date including the day of the week.

Does the calculator account for leap years?

Yes. The calculation uses JavaScript's Date API which correctly handles leap years, varying month lengths, and calendar edge cases. February 29 is properly accounted for when it exists in a leap year.

What is the maximum date range I can calculate?

The calculator supports any date that the browser's date picker allows, typically from year 0001 to 9999. For practical purposes, it handles centuries of difference without any issue.

Learn more

Date Difference Calculator: Exact Duration Between Any Two Dates

Whether you need to know how many days until a deadline, calculate someone's exact age, or figure out the duration of a contract, the Date Difference Calculator gives you precise results instantly. It computes the difference in years, months, days, weeks, hours, and even business days — all in your browser with no server calls.

How Date Difference Calculation Works

The calculator determines the elapsed time between two calendar dates by accounting for varying month lengths (28–31 days), leap years (every 4 years, except centuries not divisible by 400), and the Gregorian calendar system. The result is expressed in the largest possible units first (years, then months, then remaining days), which matches how humans naturally think about duration.

Age Calculator: Exact Age in Years, Months, and Days

The age calculator mode takes a date of birth and computes the exact age as of today. This is useful for passport applications, visa forms, insurance documents, medical records, and any context where "years old" alone isn't precise enough. The calculation handles edge cases like being born on February 29.

Business Days vs Calendar Days

Business days count only Monday through Friday. This is essential for project planning, legal deadlines (which often specify "business days"), shipping estimates, and SLA calculations. The tool shows both calendar days and business days so you can use whichever is relevant.

Adding and Subtracting Days

The add/subtract feature lets you offset any date by a number of days. Common uses include calculating due dates (e.g., "30 days from today"), finding return-by dates, planning vacation end dates, or computing notice periods. Enter negative numbers to subtract days and find past dates.

Common Use Cases

Project managers use date calculators to track sprint durations and milestone distances. HR teams calculate employee tenure and probation end dates. Legal professionals count statutory periods. Travelers plan trip durations. Parents track their child's exact age for school enrollment cutoffs. The tool is useful anywhere precision with dates matters.