Weeks Between DatesFree online date & time calculator — instant results, no sign-up
Count the number of weeks between two dates.
About the Weeks Between Dates
The Weeks Between Dates calculator measures the elapsed time between a start date and an end date in seven-day weeks. It shows the total weeks alongside whole weeks and leftover days, rather than counting calendar week boundaries. From 2026-10-23 to 2027-01-15, the result is 12 weeks, with 12 whole weeks and 0 remaining days.
- Start date
- The calendar date from which elapsed days are counted, entered in YYYY-MM-DD format; the default is 2026-10-23.
- End date
- The calendar date up to which elapsed days are counted, entered in YYYY-MM-DD format; the default is 2027-01-15.
Formula and method
D = ordinal(E) − ordinal(S); W = D / 7; Q = floor(D / 7); R = D − 7Q. For S = 2026-10-23 and E = 2027-01-15: D = 84 days, W = 84 / 7 = 12 weeks, Q = 12 whole weeks, and R = 84 − 7 × 12 = 0 days.
- SStart date.
- EEnd date.
- ordinal(date)A calendar date's sequential day number, used to find the elapsed calendar-day difference.
- DElapsed calendar days between the dates.
- WTotal weeks, including any fractional week.
- QNumber of complete seven-day weeks; floor rounds the quotient down.
- RDays left after removing the whole weeks.
Find the elapsed calendar-day difference between the two dates, accounting for month lengths and leap years. Divide that difference by seven to obtain total weeks. For an end date on or after the start date, take the integer quotient as whole weeks and the remainder as remaining days. The default interval contains 84 elapsed days, which divides exactly into 12 weeks.
Worked example
These are the calculator's starting values and the results it actually produces for them.
Inputs
- Start date1970-01-01
- End date1970-03-26
Results
- Weeks12
- Whole weeks12
- Remaining days0
How to use the Weeks Between Dates
- 1Enter 2026-10-23 in Start date to use the default beginning of the interval.
- 2Enter 2027-01-15 in End date to use the default end of the interval.
- 3Run the calculation to convert the elapsed calendar days into weeks.
- 4Read Weeks = 12 as the total duration expressed in seven-day weeks.
- 5Check Whole weeks = 12 and Remaining days = 0 to confirm that no partial week remains.
Reading your result
Weeks reports the entire elapsed interval divided by seven and may include a fractional part. Whole weeks reports the complete seven-day periods in the interval. Remaining days reports the days beyond those complete weeks, from 0 through 6 for a nonnegative interval. With the default inputs, Weeks = 12, Whole weeks = 12, and Remaining days = 0 all describe the same 84-day duration.
Limitations
This calculation uses elapsed days, not an inclusive count of both endpoint dates. Weeks are fixed seven-day periods, not ISO week numbers or Monday-to-Sunday calendar weeks. Weekends and holidays are included. Date-only arithmetic does not measure exact elapsed hours or adjust the result for daylight saving time. The formulas and interpretation here assume the end date is on or after the start date; handling of reversed dates and display rounding depends on the calculator's implementation.
Common questions
Why do 2026-10-23 and 2027-01-15 give exactly 12 weeks?+
The dates are 84 elapsed calendar days apart. Dividing 84 by seven gives 12 with no remainder, so the output is 12 weeks, 12 whole weeks, and 0 remaining days.
Does this calculator count both the start date and end date as full days?+
No. It measures the difference between the dates rather than counting both endpoints inclusively. The start date is the zero point of the elapsed interval.
Does crossing a Monday or a new year add another week?+
No. Only complete groups of seven elapsed days add whole weeks. The default interval crosses into 2027, but that year boundary does not change the calculation.
How do fractional weeks relate to remaining days?+
The fractional part of Weeks represents Remaining days divided by seven. Equivalently, total weeks equals whole weeks plus remaining days divided by seven; for the default dates, zero remaining days means no fractional week.
Does the calculator save my information?+
Calculations run in your browser. While signed in, inputs and results are automatically recorded in account history; saving a result creates a separate saved record.
Further reading
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Results are estimates for informational purposes and are not financial, medical or legal advice.