gizmobench

Days to Weeks Converter

A week is exactly 7 days, so days to weeks is one division: weeks = days / 7. Multiples of seven land whole, so 7 days is 1 week, 14 days is 2 and 28 days is exactly 4, and everything in between carries the repeating decimal that one seventh always produces: 30 days is 4.28571428571 weeks, 90 days is 12.8571428571 and 100 days is 14.2857142857. This page opens the converter with Day in the From box and Week in the To box, ahead of whatever pair you last used, and prints the answer to twelve significant digits as you type. What it gives is a decimal count of weeks, not a weeks-and-days remainder, so 10 days reads 1.42857142857 weeks rather than 1 week and 3 days. Under the headline the same span appears in every other common time unit at once, so 1 day shows as 24 hours, 1,440 minutes, 86,400 seconds and 86,400,000 milliseconds beside its 0.142857142857 weeks, and an Uncommon units switch labelled Show 2 more adds nanoseconds and microseconds when a span is small enough to need them.

To0.142857142857
Category
Time
Base unit
second
Uncommon units

1 d in every time unit

  • Millisecondms
    86,400,000
  • Seconds
    86,400
  • Minutemin
    1,440
  • Hourh
    24
  • Weekwk
    0.142857142857
  • Year (Julian)yr
    0.00273785078713

Common questions

How many weeks is 30 days?
4.28571428571 weeks, because 30 is not a multiple of 7. That number is the reason a month and a week never line up: 28 days is exactly 4 weeks, 30 days is 4.28571428571 and 31 days is 4.42857142857, so only February in a common year is a whole number of weeks. Other spans people ask for come out the same way: 45 days is 6.42857142857 weeks, 60 days is 8.57142857143 and 92 days, a long quarter, is 13.1428571429.
What is the formula for days to weeks?
weeks = days / 7, and days = weeks x 7 going back. The converter holds both directions on one factor: a week is stored as 604,800 seconds and a day as 86,400, and 604800 / 86400 is 7 exactly. Press the swap button between the two boxes to reverse the pair, where 1 week gives 7 days, 4 weeks gives 28, 12 weeks gives 84 and half a week gives 3.5.
Worked example: how many weeks is 365 days?
52.1428571429 weeks. A leap year of 366 days is 52.2857142857 weeks, and 52 whole weeks is only 364 days, which is why a calendar year drifts forward a day of the week each time. The Julian year in the unit list is a different length again, 365.25 days, and reads 52.1785714286 weeks. Use whichever matches the year you mean, since the page cannot know which calendar year you are counting.
Why does the answer keep repeating the same digits?
Because one seventh is 0.142857142857... and the block 142857 repeats forever. One day is 0.142857142857 weeks here, which is that repeat cut off at twelve significant digits, the precision the whole converter prints to. Nothing is lost in the arithmetic itself: the division is done in full double precision and only the printed form is rounded, so pressing Copy result gives you the same twelve digits without the thousands separators.
How do I get an answer in weeks and days instead of a decimal?
Take the whole number of weeks from the answer, multiply it back by 7, and subtract. For 30 days the answer is 4.28571428571, so 4 whole weeks is 28 days and 2 days are left over: 4 weeks and 2 days. For 100 days it is 14.2857142857, so 14 weeks is 98 days and 2 days remain. The converter itself stays with the decimal, because that is the form that goes straight into another calculation.
How many weeks is 90 days?
12.8571428571 weeks, a fortnight short of 13. Three calendar months are usually 90, 91 or 92 days, which is 12.8571428571, 13 or 13.1428571429 weeks, so a quarter is roughly 13 weeks but exactly 13 only when it runs to 91 days. Six months of 180 days is 25.7142857143 weeks and 200 days is 28.5714285714.
Does this follow the calendar, with leap days and clock changes?
No, and that is worth knowing before you use the number. Every unit here is fixed arithmetic: a day is 86,400 seconds and a week is 604,800, with no leap days, no daylight saving hour and no leap seconds. For a span between two real dates, where those things move the total, work the dates out first and convert the resulting day count here.
Why does the page open on days and weeks when I last converted something else?
Because a page named for one pair should arrive showing that pair. Days and weeks are set on load ahead of the pair the converter remembered, and the main unit converter keeps its own memory untouched: go back to it and it is still where you left it. The number you last typed does follow you here, since it is usually the one you are still working with.
Does anything I type leave the browser?
No. The factors are constants in the page, the division runs in your browser as you type, and nothing is uploaded or stored on a server. No account is involved, and the page keeps converting if your connection drops after it has loaded.

Conversion factors are the exact legal definitions where one exists. An inch is exactly 2.54 cm and a pound exactly 0.45359237 kg, so those conversions are exact rather than approximate. Temperature uses offsets rather than factors, and that is shown in the working.