How to Use the Date Duration Calculator

Calculating the time between two dates is simple:

Select a start date — Click the first date picker and choose your starting point.
Select an end date — Choose the end date in the second picker.
Click Calculate — Instantly see the total duration in days, weeks, months, years, workdays and weekends.

The calculator includes both the start and end dates in the count. Workdays (business days) count Monday through Friday, excluding weekends. Weekends count Saturday and Sunday.

Common Use Cases

Project planning: How many working days until a deadline? Calculate the exact workdays between today and your project due date.
Holiday and travel planning: Count the days until your next holiday, or calculate how many days you spent travelling.
Pregnancy due dates: Calculate how far along a pregnancy is by counting from the start of the last menstrual period.
Employment duration: How many years, months and days has someone been employed at a company?
School and academic calendars: Calculate the duration of a school term or the days remaining until exams.
Legal and contract dates: Count the number of days between two dates for contract periods, notice periods or settlement dates.
Age calculation: Quickly find how many days old someone is — useful for baby ages, pet ages, or milestone celebrations.
Savings and habit tracking: See how many days you've been saving money, learning a skill, or maintaining a streak.

How Duration is Calculated

Here's a breakdown of how each metric is calculated:

Total Days: The calendar days between the start date and end date, inclusive of both dates.
Weeks: Total days divided by 7. Shown with one decimal place.
Months: Based on the difference in month/year values. Accounts for date-of-month comparisons.
Years: Difference in calendar years, adjusted if the end date hasn't reached the anniversary of the start date.
Workdays: Days from Monday to Friday, excluding Saturdays and Sundays.
Weekends: Saturdays and Sundays only.

Frequently Asked Questions

Does the calculator include both the start and end dates? ▾

Yes. The calculator counts from the start date through the end date, including both dates. For example, from Monday to Wednesday is 3 days (Mon, Tue, Wed), not 2.

What counts as a workday? ▾

Workdays (business days) are Monday through Friday inclusive. Weekends (Saturday and Sunday) are excluded from the workday count. Public holidays are not excluded — the calculator counts standard workdays only. For Australian public holiday-adjusted calculations, you'll need to consult a business calendar.

How are months calculated? ▾

Months are calculated by comparing the year and month difference between the two dates, then adjusting for the day of the month. For example, from 15 January to 15 March is exactly 2 months. But from 31 January to 28 February (non-leap year) is counted as approximately 1 month because February doesn't have 31 days.

Does this calculator account for leap years? ▾

Yes. The JavaScript Date object handles leap years correctly. February 29 in leap years is recognised, and day calculations between dates spanning a leap year will include the extra day automatically.

Disclaimer: This calculator provides approximate durations for general informational purposes. For legal, contractual or official purposes, always consult the relevant governing documents or a qualified professional.

Related Utility Tools

More time and date tools you might find useful.

Age Calculator — Calculate exact age in years, months and days
Time Calculator — Add, subtract and convert time durations
Percentage Calculator — Quick percentage calculations
Unit Converter — Convert between metric and imperial units