Free Online Week Calculator
This free week calculator tells you how many complete weeks and remaining days are between two calendar dates. Enter a start date and an end date to see the total number of days, the equivalent number of weeks in decimal form, the weekday for each date, and the ISO week number.
A week is normally seven days, so a date range can be expressed as complete seven-day periods plus any days left over. For example, 25 days is 3 weeks and 4 days, or about 3.57 weeks. The calculator makes these conversions automatically.
How to Calculate Weeks Between Two Dates
The basic calculation starts by finding the number of elapsed calendar days between the start date and end date. That day count is divided by 7 to find complete weeks and a remainder.
Complete weeks = floor(total days ÷ 7)
Remaining days = total days mod 7
For example, if two dates are 24 days apart, the result is 3 complete weeks and 3 remaining days. The decimal-week result is 24 ÷ 7, which is approximately 3.43 weeks.
What This Week Calculator Shows
The calculator provides several ways to understand the same date interval:
- Complete weeks and remaining days: the interval expressed in whole weeks plus leftover days.
- Total days: the underlying number of days used for the calculation.
- Decimal weeks: total days divided by seven.
- Start and end weekdays: the day of the week for each selected date.
- ISO week numbers: the ISO calendar week associated with each date.
Should You Include the End Date?
Date calculators can produce different answers depending on whether the final date is included in the count. By default, this calculator uses the elapsed interval between the two dates, so the start date is the reference point and the end date marks where the interval finishes.
If you want to count both boundary dates as calendar days, enable the Include the end date option. This adds one day to the calculated interval. The option is useful when you are counting calendar days in a range rather than measuring elapsed time between two dates.
Weeks Between Dates Examples
7 Days
A seven-day interval equals exactly 1 week. There are no remaining days.
14 Days
Fourteen days equals exactly 2 weeks.
25 Days
Twenty-five days equals 3 complete weeks and 4 remaining days. In decimal form, it is approximately 3.57 weeks.
30 Days
Thirty days equals 4 complete weeks and 2 remaining days, or approximately 4.29 weeks.
What Is an ISO Week Number?
ISO week numbering is an international calendar convention in which weeks begin on Monday. ISO week 1 is the week containing the year's first Thursday. Because ISO weeks can cross calendar-year boundaries, the ISO week-year can sometimes differ from the ordinary calendar year shown by the date.
The week number displayed by this calculator is useful when comparing dates with schedules, business reporting systems, project plans, and other applications that use ISO week numbering.
Common Uses for a Week Calculator
Project Planning
Calculate how many weeks remain between a project start date and a deadline. Expressing a schedule in weeks can make longer planning periods easier to understand.
Pregnancy and Due-Date Planning
Week-based date calculations are commonly used when tracking pregnancy timelines. This calculator can measure the calendar interval between two dates, but it does not estimate a pregnancy due date or provide medical advice.
School and Academic Planning
Students and educators can use the tool to estimate the number of weeks between important dates such as a term start and an examination date.
Work and Vacation Planning
Use the calculator to see how many weeks and days separate work dates, holidays, travel dates, or other calendar events.
Weeks Versus Days
Weeks are convenient for describing longer periods because each week contains exactly seven days. Days are more precise when a date range does not contain a whole number of weeks. This is why the calculator displays both complete weeks and remaining days.
Decimal weeks are useful when you need a single numerical value. To convert days into weeks, divide the number of days by 7. To convert weeks into days, multiply the number of weeks by 7.
Limitations of Date and Week Calculations
This calculator works with calendar dates and whole-day intervals. It does not account for a specific time of day, time zone, daylight-saving transition, or business-day rules. If you need working days rather than calendar days, a business-day calculator is more appropriate.
Calendar calculations can also differ when a system uses a different rule for including the start or end date. Always check the counting convention when comparing results from different calculators.
Frequently Asked Questions About Weeks Between Dates
How many days are in a week?
One week contains 7 days.
How do I calculate weeks between two dates?
Find the number of elapsed days between the two dates and divide that number by 7. The whole-number portion gives complete weeks, while the remainder gives additional days.
How many weeks are 30 days?
Thirty days is 4 weeks and 2 days, or approximately 4.29 weeks.
How many weeks are 28 days?
Twenty-eight days is exactly 4 weeks.
Does the calculator count the end date?
By default, the calculator measures the elapsed interval between the dates. You can enable the Include the end date option when you want the final calendar day included in the day count.
What is a decimal week?
A decimal week expresses a day interval as one numerical number of weeks. It is calculated by dividing total days by 7.
What is an ISO week number?
An ISO week number identifies a calendar week using the ISO 8601 week-date convention. ISO weeks start on Monday, and the first ISO week is the one containing the year's first Thursday.
Can I calculate weeks in the past?
Yes. The calculator accepts any valid start and end dates. If the end date is earlier than the start date, the calculator reports the interval as a positive distance and indicates the direction of the date range.
Week Calculator Disclaimer
Results are calendar calculations intended for general informational and planning purposes. The calculator does not provide medical, legal, financial, employment, or other professional advice. For decisions that depend on a specific calendar, contract, medical schedule, or official deadline, verify the dates and counting rules with the relevant source.