How Many Weeks and Months Are Between Two Dates? How to Work It Out

The short answer

To find the weeks between two dates, count the days between them and divide by 7: the whole number is full weeks and the remainder is extra days. The Date Difference Calculator does the day count for you and shows days, full weeks, an estimated number of months, years, hours and minutes. For an exact "X months and Y days" answer, count calendar months from the start date and then add the leftover days, because months are not all the same length.

How the calculator counts

Enter a start date and an end date, and the results appear straight away. Here is what each box means:

Result	How it is worked out
Days	Days from the start date up to the end date (the end date is not counted)
Weeks	Days ÷ 7, rounded down to full weeks
Months	Days ÷ 30.44, rounded to the nearest whole number
Years	Days ÷ 365.25, to two decimal places
Hours and Minutes	The time between the two dates at midnight

If you enter the dates the wrong way round, the calculator swaps them, so the answer is always positive.

There is also a Business days only (exclude weekends) checkbox. When it is ticked, Days counts only Monday to Friday and the Weeks and Months figures are worked out from that smaller number. Leave it unticked when you want calendar weeks.

Worked examples

These figures were calculated in code using the same method as the calculator.

From	To	Days	Weeks and days	Months shown	Calendar months and days
15 Jan 2026	21 Oct 2026	279	39 weeks 6 days	9	9 months 6 days
21 Oct 2026	25 Dec 2026	65	9 weeks 2 days	2	2 months 4 days
31 Jan 2026	1 Mar 2026	29	4 weeks 1 day	1	see below

The calculator shows full weeks only, so it displays 39 for the first row. To get the leftover days, multiply the weeks by 7 and subtract from the days: 279 − (39 × 7) = 6.

Counting weeks by hand

Find the number of days between the dates.

Divide by 7.

The whole number is the full weeks.

Multiply that by 7 and subtract from the days to get the remainder.

Example: 65 ÷ 7 = 9.29, so 9 full weeks. 9 × 7 = 63, and 65 − 63 = 2. Answer: 9 weeks and 2 days.

A shortcut for checking: if both dates fall on the same weekday, the gap is an exact number of weeks with no leftover days.

Counting calendar months exactly

The "Months" box is an estimate. An average month is about 30.44 days (365.25 ÷ 12), which is fine for "roughly how long", but it does not match how people usually count months in contracts, notice periods or rental agreements. For those, count like this:

Step forward from the start date one month at a time, keeping the same day number, until the next step would pass the end date.

Count the steps. That is the number of full months.

Count the days from the last step to the end date. That is the leftover.

Example: 15 January to 21 October. Stepping 15 Feb, 15 Mar and so on reaches 15 October after 9 steps. From 15 October to 21 October is 6 days. Answer: 9 months and 6 days.

The month-end problem

Start dates on the 29th, 30th or 31st are awkward, because not every month has those days. From 31 January, one month later could be read as 28 February, 1 March or 3 March depending on the convention. Contracts and HR policies usually define this; if yours does not, state the exact end date rather than "one month". For the 31 January to 1 March 2026 example, the safest description is simply "29 days".

When to use weeks, months or days

• Notice periods and deadlines: use the exact wording of the agreement. "30 days" and "one month" are not the same period.
• Project plans: weeks are easier to schedule. Pair the week count with the weekday the project starts.
• Counting down to an event: weeks and days ("9 weeks and 2 days to go") are easy to grasp.
• Age: use the Age Calculator, which gives years, months and days from a date of birth.
• Working days only: tick the business days box, or read the guide to counting working days if you also need to remove public holidays.

Inclusive or exclusive?

The calculator counts the gap between dates, so the end date is not included. 1 March to 2 March is 1 day. Many forms and leave policies count both the first and the last day; in that case add 1 to the day count before dividing by 7. The guide to counting days between two dates explains when each method is used.

Common mistakes

Rounding weeks up

39.86 weeks is 39 full weeks and 6 days, not 40 weeks. Round down and state the leftover days.

Treating the months estimate as exact

The months figure is rounded from days ÷ 30.44. It is good for a quick sense of scale but can be off by one compared with a calendar count, especially near month ends.

Forgetting the business days box is ticked

If the numbers look too small, check whether Business days only is on. It removes Saturdays and Sundays before the weeks and months are calculated.

Mixing up the dates in a spreadsheet

If you use a spreadsheet, subtracting two date cells gives days. Divide by 7 for weeks. Make sure both cells are real dates rather than text, or you will get an error or a wrong result.

Summary

• Weeks = days ÷ 7; keep the whole number and state the remainder in days.
• The calculator's Months box is an estimate based on 30.44-day months.
• For exact months, count calendar months from the start date, then add the leftover days.
• The end date is not counted; add 1 if you need both dates included.
• Untick business days when you want calendar weeks.