📅 Date & Time

Days Between Dates Calculator

Calculate the exact number of days between any two dates — including business days, weeks, months, and years. Works for past and future dates.

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📅 Days Between Dates Calculator

Select your start and end dates — the exact day count appears instantly.

The earlier date
The later date
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Days Between Dates Calculator

This free days between dates calculator tells you the exact number of days between any two dates — past, present, or future. Enter a start date and end date to instantly see the total in calendar days, business days (excluding weekends), weeks, months, and years. Whether you are tracking a project deadline, calculating a contract duration, planning a trip, or working out how long ago something happened — this calculator gives you the precise answer in seconds.

Manually counting days between dates is surprisingly error-prone, especially across month boundaries, leap years, and year changes. This calculator handles all edge cases automatically using the exact Gregorian calendar, including full leap year awareness and correct month-end boundary handling.

How Is the Day Count Calculated?

The calculator computes the difference between two calendar dates by comparing their timestamps in milliseconds and converting to whole days:

Total days = (End date − Start date) in milliseconds ÷ 86,400,000
Business days = count of Mon–Fri between the two dates
Weekend days = Total days − Business days

Business days are calculated by iterating through each day in the range and counting only Monday through Friday. The calculator correctly handles leap years, month-end boundaries, and year crossings.

💡 Business days exclude Saturday and Sunday but do NOT exclude public holidays — holiday schedules differ by country. Subtract public holidays manually from the business days result if required.

How to Use This Calculator

  1. Start date: Select the earlier of the two dates.
  2. End date: Select the later date. The calculator auto-swaps if entered in reverse.
  3. Exclude weekends (optional): Tick to see the count in business days (Mon–Fri only) — useful for work deadlines and project timelines.
  4. Include end date (optional): By default the end date is not counted. Tick to include both the first and last day — useful when counting event days.
  5. Calculate: Click the button to see total days, business days, weekend days, weeks, months, and years.

Common Uses

  • Project management: Calculate working days between kick-off and delivery to plan sprints and milestones accurately.
  • Legal and contracts: Many contracts specify notice periods and payment terms in calendar days — find the exact end date instantly.
  • Travel planning: Count days between departure and return to confirm trip length, visa duration, or travel insurance period.
  • Age and anniversaries: Find exactly how many days since a wedding, birthday, or milestone event.
  • Finance and payroll: Count business days between invoice date and payment due date, or working days in a pay period.
  • Health and medical: Track days between appointments, medication durations, or days in a cycle.

Worked Example

A fixed-term contract starts on 1 March 2025 and ends on 31 August 2025. Entering these dates gives: 183 total calendar days, approximately 131 business days, 52 weekend days, and exactly 6 calendar months. If the contract requires "180 calendar days notice", counting forward from 1 March lands on 28 August 2025 — two days before the end date, which may affect notice obligations. This is exactly the kind of edge case where manual counting fails and a calculator is essential.

Frequently Asked Questions

Does this calculator include both the start and end date in the count?
By default, the calculator counts from the start date up to but not including the end date — the standard date difference method. Monday to Friday = 4 days by default. Tick "Include end date" to count both endpoints, giving 5 days for the same range. Use the default for durations; use include end date when counting discrete days such as event days.
Does this calculator account for leap years?
Yes — the calculator uses JavaScript's built-in Date object which fully handles leap years. February 29 in a leap year is counted as a valid calendar day when it falls within your selected date range. All month-end boundaries including February 28/29 and April 30 are handled correctly.
Are public holidays excluded from the business days count?
No — business days means Monday to Friday only, with Saturday and Sunday excluded. Public holidays are not excluded because holiday schedules differ by country and state. If you need to exclude specific public holidays, subtract them manually from the business days result shown.
Can I calculate days between dates in the past?
Yes — this calculator works for any two dates, past or future, with no minimum or maximum range. You can calculate days between dates centuries apart or just one day apart. Enter any two dates and click Calculate.
What is the difference between calendar days and business days?
Calendar days count every day including weekends and public holidays. Business days count only Monday through Friday. Monday to the following Monday is 7 calendar days but 5 business days. Use calendar days for legal and travel calculations. Use business days for work deadlines and project timelines.
How do I calculate days until a future date?
Set today as the Start Date and your target future date as the End Date, then click Calculate. The result shows exactly how many days remain. For common future events, our Days Until Calculator has handy presets.
How accurate is this calculator?
Fully accurate for all Gregorian calendar dates. Uses millisecond-precision timestamp arithmetic and correctly handles leap years, month-end edge cases, and year crossings. Results match Excel DAYS() and Google Sheets DATEDIF() functions.
Is this days between dates calculator free?
Yes — completely free with no registration or login required. All calculations happen instantly in your browser. NerdyTools is supported by non-intrusive advertising, which keeps all tools free for everyone.
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