How do I find the number of days between two dates?

Switch to difference mode, enter a start date and an end date, and the calculator shows the number of whole days between them, updating as you type. By default it counts the gap — the number of nights between the two dates. If you want to count both the first and last day, tick “include the end day”, which adds one to the total.

How do I add or subtract time from a date?

Switch to add-or-subtract mode, pick your start date, choose Add or Subtract, then enter any mix of years, months, weeks and days. The calculator returns the resulting date along with its weekday. Years and months are applied first, then weeks and days, which matches how people normally think about “three months and ten days from now”.

Does it count working days?

Yes. In difference mode the calculator splits the span into working days (Monday to Friday) and weekend days (Saturday and Sunday), which is useful for notice periods, delivery windows and contract terms. It does not deduct public holidays, because those differ by country and region, so treat the working-day figure as a Monday-to-Friday count.

Should I include the end day or not?

It depends on what you are counting. For “how many days until” a date, leave the end day out — the gap is what matters. For things like a hotel stay or an event that occupies both the first and last day, include the end day so both are counted. For example, 1 January to 3 January is 2 days as a gap, or 3 days if you count every day inclusively.

What happens when adding a month lands on a date that doesn’t exist?

The calculator uses the standard month-end rule: if the target month is shorter, it clamps to that month’s last valid day. So adding one month to 31 January gives 28 February (or 29 February in a leap year), because February has no 31st. This is the same convention used by spreadsheets and most scheduling software, and it keeps repeated monthly steps predictable.

Date Calculator

The Date Calculator does the two things people most often need with dates, in one place. Use difference mode to count the days between two dates — shown also as weeks, working days versus weekends, and years, months and days, with an option to include the end day. Use add-or-subtract mode to shift a…

Start date

End date

Pick two dates.

Created with❤️byeaglecalculator.com

HOW TO USE

1
Choose a mode: “Difference between dates” or “Add / Subtract from a date”.
2
For a difference, pick a start and end date; tick “include the end day” to count both endpoints.
3
To add or subtract, pick a start date, choose Add or Subtract, and enter years, months, weeks or days.
4
Read the result — days, weeks, working days and Y/M/D for a difference, or the resulting date and weekday.

TWO WAYS TO WORK WITH DATES

This date calculator does the two things people most often need. In difference mode it counts the whole days between two dates — with an option to include the end day — and also shows the span as weeks, as working days versus weekends, and as years, months and days. In add-or-subtract mode it shifts a date forward or backward by any number of years, months, weeks or days and gives you the resulting date and weekday. Years and months are applied with the standard calendar rule, so adding a month to 31 January lands on the last day of February, and every leap day is counted.

WHAT PEOPLE USE IT FOR

Deadlines & due dates

Find the date a set number of days, weeks or months from a start — or how long until a deadline.

Countdowns & “days since”

Count the days until an event, or how many have passed since one.

Notice & working periods

Measure spans in working days for notice periods, deliveries and contracts.

Planning & scheduling

Project renewal, return and appointment dates in a single step.

FREQUENTLY ASKED QUESTIONS

A date calculator works out dates and the spans between them so you do not have to count on a calendar. This one covers the two most common tasks: finding how much time lies between two dates, and finding the date that falls a certain amount of time before or after a starting date. It shows the answer several ways — days, weeks, working days and calendar years/months/days — so you can use whichever unit fits your situation.

Measures the gap between two dates.
Finds a date a set distance before or after another.
Shows results in days, weeks, working days and Y/M/D.
Handles leap years and month lengths automatically.

NOTES & REFERENCES

Difference mode counts the gap between two dates; “include the end day” adds one to count both endpoints.
Add/subtract applies years and months first (clamping to the last valid day), then weeks and days.
All counting uses the Gregorian calendar and includes every 29 February in the span.
Working days count Monday to Friday; public holidays are not deducted.

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Last updated: — · Calendar-accurate with full leap-year handling · Verified by the EagleCalculator team · Eagle-eyed accuracy for every calculation.