Days between dates calculator
Calculate the number of days, weeks and months between two dates.
Espacio publicitario
Espacio publicitario
How the days between dates are calculated
The calculator subtracts the start date from the end date and converts the difference in milliseconds into full days:
days = (end date − start date) ÷ 86,400,000
From the total number of days, complete weeks are obtained by dividing by 7, and an approximation in months by dividing by 30.44 (the average number of days per month in a year). If the end date is earlier than the start date, the result is shown as an absolute value.
Worked example
Between January 1, 2026 and September 8, 2026 there are 250 days, which is equivalent to 35 full weeks and approximately 8.2 months.
Frequently asked questions
- How are the days between two dates calculated?
- The start date is subtracted from the end date, and the difference in milliseconds is converted to days by dividing by 86,400,000 (the number of milliseconds in a day).
- Does the calculator count both the start and end day?
- It calculates the exact difference between the two dates at 00:00, so the start day isn't counted as a full day unless it's explicitly included in the range.
- What happens if the end date is earlier than the start date?
- The calculator shows the number of days as an absolute value, giving the difference regardless of the order of the dates.
- Why isn't the number of months a whole number?
- Months don't all have the same length, so the calculator uses an average of 30.44 days per month to give an approximation in months.
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