Days Between Dates Calculator

Count the days between two dates, with weeks, months, business days and an option to include the end date. Example: January 1 to December 25, 2026 is 358 days, or 51 weeks and 1 day.

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Start date

End date

Include the end date

How to use the Days Between Dates Calculator

Pick the start date and the end date.
Choose whether to count the end date too.
Press Calculate to see days, weeks, months and business days.

Formula and method

Days between = end date minus start date, using the calendar so leap years are handled. Add 1 to include both the start and the end day.

Worked example: Jan 1 to Dec 25, 2026

Measure	Result
Days	358
Weeks and days	51 weeks, 1 day
Months and days	11 months, 24 days

Days in each month

Month	Days
January	31
February	28 (29 in leap years)
March	31
April	30
May	31
June	30
July	31
August	31
September	30
October	31
November	30
December	31

Leap years

A leap year has 366 days. It happens every 4 years, except century years not divisible by 400. 2024 and 2028 are leap years; 2100 is not.

Frequently asked questions

How do I count days between two dates?

Subtract the earlier date from the later one. The calculator handles months of different length and leap years.

Does it include the end date?

Not by default. Switch the option to Yes to count both the first and last day.

How many business days are there?

The tool counts Monday to Friday. Subtract public holidays yourself.

Can the start date be after the end date?

Yes. The tool swaps them and gives the same count.

How many days are in a year?

365, or 366 in a leap year.

How many weeks is 100 days?

14 weeks and 2 days.

Sources

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Effortless Math Team

15 minutes ago