Weeks Between Dates Calculator

What is a weeks between dates calculator?

The weeks between dates calculator is a quick tool that tells you how many weeks separate two calendar dates. You pick a start date and an end date, and the calculator returns the number of whole weeks between them. It can also express the same span in years, months, days, hours, minutes, or seconds, so a single calculation answers several questions at once.

Counting weeks by hand is error-prone because months have different lengths and leap years add an extra day. This tool handles those details automatically, which makes it useful for planning pregnancies, scheduling sprints, tracking subscriptions, counting down to a deadline, or measuring how long a project has been running.

How does the calculator work?

The calculator first measures the full span between the two dates in days, then divides that total by seven to convert it into weeks. The end date is the later of the two dates, and the result is the count of complete weeks; the remaining days that do not make up a full week are dropped from the week total.

The basic formula is:

$$\text{Weeks} = \left\lfloor \frac{\text{End Date} - \text{Start Date}}{7} \right\rfloor$$

Where:

• $\text{End Date} - \text{Start Date}$ is the total number of days between the two dates.
• The $\lfloor \; \rfloor$ symbols mean the result is rounded down to a whole number of weeks.

If you switch the result units to days, the calculator simply reports $\text{End Date} - \text{Start Date}$ without dividing.

Examples

Example 1: A full year

How many weeks are between January 1, 2020 and January 1, 2021?

$$\text{Days} = \text{January 1, 2021} - \text{January 1, 2020} = 366$$

Because 2020 is a leap year, the span is 366 days. Dividing by seven:

$$\text{Weeks} = \left\lfloor \frac{366}{7} \right\rfloor = 52$$

So there are 52 whole weeks (with 2 extra days) between the two dates.

Example 2: Two weeks

How many weeks are between January 1, 2025 and January 15, 2025?

$$\text{Days} = \text{January 15, 2025} - \text{January 1, 2025} = 14$$ $$\text{Weeks} = \left\lfloor \frac{14}{7} \right\rfloor = 2$$

The 14-day span is exactly 2 weeks.

Example 3: Same date

If the start and end dates are identical, no time has passed, so the result is 0 weeks (and 0 days).

Practical notes

• The end date is not included in the count, so the result reflects full days that have elapsed between the two dates.
• Leap years are handled automatically; you do not need to add or remove a day yourself.
• Switching the result units to days is handy when you need an exact day count rather than rounded weeks. For a dedicated day count, see the days between dates calculator.
• If the end date is earlier than the start date, the calculator reports the absolute distance, so the order of the two dates does not change the magnitude of the answer.

Frequently asked questions (FAQs)

How are partial weeks handled?

Only whole weeks are counted. A span of 16 days, for example, returns 2 weeks, because the remaining 2 days do not form a third full week. Switch the units to days if you need to see those leftover days.

Does the calculator count weekends?

Yes. Every day in the span counts toward the total, including Saturdays and Sundays. The result is the number of calendar weeks, not working weeks.

Can I use it to count pregnancy weeks?

You can use it to measure the number of weeks between two dates, such as a last-period date and today. Clinical pregnancy dating uses its own conventions, so treat the result as a general week count rather than medical advice.

What happens with leap years?

Leap years add an extra day to February, and the calculator includes that day automatically. That is why a full year starting in a leap year, such as 2020, spans 366 days, or 52 weeks and 2 days.