How weeks between dates are counted
First the calculator finds the number of days between your two dates, then divides by 7 to get weeks. From 1 January 2026 to 31 December 2026 is 364 days, which is exactly 52 weeks.
Because the count runs on real calendar days, month lengths, year boundaries and leap days are all handled for you. From 1 January 2024 to 1 January 2025 is 366 days, or 52 weeks and 2 days, since 2024 was a leap year — one day more than the same span starting a year later.
People working on this usually reach for the days between dates calculator too.
How to use this calculator
Pick a start date and end date. The result shows decimal weeks plus full weeks and leftover days. To count only working days in that span, use the business days calculator, or convert larger gaps with the hours to days calculator.
Reading a decimal result: 40.5 weeks means 40 full weeks plus three and a half days, because half a week is 3.5 days. When a schedule needs whole weeks, round down and handle the remaining days separately rather than rounding the week count up.
Why a year is about 52 weeks
A common year has 365 days; divided by 7 that is 52 weeks and 1 day. A leap year has 366 days, giving 52 weeks and 2 days. That extra day or two is why the calendar weekday shifts each year.
Spans worth knowing: a 40-week pregnancy is 280 days, a 12-week school term is 84 days, a 6-week notice period is 42 days, and 13 weeks is 91 days — the usual length of a financial quarter.
Frequently asked questions
- How many weeks between Jan 1 and Dec 31, 2026?
- That span is 364 days, which is exactly 52 weeks.
- How do I count weeks between two dates?
- Find the number of days between the dates and divide by 7. The whole part is full weeks and the remainder is leftover days.
- How many weeks are in a year?
- A year has about 52 weeks — 52 weeks plus 1 day in a common year, or plus 2 days in a leap year.
- Does the order of dates matter?
- If the end date is before the start date the result is negative, showing how many weeks back in time the dates are.
- Does the result include the end date itself?
- It measures the gap between the two dates, so the end date is not counted as an extra day: 1 January to 8 January is exactly 1 week, not 8 days. If you need both endpoints included, as with a hire or holiday period, add one day before dividing by 7.