Days to Weeks Calculator
Enter a number of days to see how many weeks that equals, shown as both a decimal and as whole weeks plus remaining days. You also get the equivalent in hours, minutes, months and years. Switch the mode to convert the other way and turn weeks into days. Results update as you type.
Formula
Worked example
90 days to weeks: 90 / 7 = 12.857 weeks. The whole-week portion is floor(12.857) = 12 weeks. The remainder is 90 - (12 x 7) = 90 - 84 = 6 days. So 90 days = 12 weeks and 6 days.
How to convert days to weeks
The conversion is straightforward: there are exactly 7 days in every week, so dividing your day count by 7 gives you the equivalent in weeks. For example, 90 days / 7 = 12.857 weeks. If you want a more readable result, you can split that into whole weeks and a remainder: 12 complete weeks and 6 leftover days (because 12 x 7 = 84, and 90 - 84 = 6). Use the decimal form for arithmetic - such as scheduling or calculating rates per week - and the mixed form for communication.
Converting weeks back to days
To reverse the calculation, multiply the number of weeks by 7. Switch the mode above to "Weeks to days" and enter any value, including decimals (for example, 2.5 weeks = 17.5 days). This is useful when you have a duration expressed in weeks and need to know the exact day count for a calendar or project schedule.
Other time unit equivalents
This calculator also shows hours (days x 24), minutes (days x 1,440), approximate months (days / 30.4375, using the mean Gregorian calendar month of 365.25 / 12 days), and approximate years (days / 365.25, using the Gregorian year length). These secondary outputs help when you are bridging between systems - for example, checking whether a 90-day trial fits inside a calendar quarter, or whether a 180-day limit is closer to 6 months.
Practical uses for days-to-weeks conversion
Project managers use week-based planning, while contracts, trial periods and medication schedules are often written in days. Converting between the two avoids off-by-one errors. A 30-day notice period is 4 weeks and 2 days, not a clean 4 weeks, which matters when counting to a calendar date. A 100-day plan is 14 weeks and 2 days, often rounded to a 14-week campaign. A pregnancy is 280 days = 40 weeks, which is why gestational age is always quoted in weeks.
Days to weeks quick-reference table
| Days | Weeks (decimal) | Weeks and days |
|---|---|---|
| 1 | 0.1429 | 0 weeks and 1 day |
| 7 | 1.0000 | 1 week exactly |
| 14 | 2.0000 | 2 weeks exactly |
| 21 | 3.0000 | 3 weeks exactly |
| 28 | 4.0000 | 4 weeks exactly |
| 30 | 4.2857 | 4 weeks and 2 days |
| 45 | 6.4286 | 6 weeks and 3 days |
| 60 | 8.5714 | 8 weeks and 4 days |
| 90 | 12.8571 | 12 weeks and 6 days |
| 100 | 14.2857 | 14 weeks and 2 days |
| 120 | 17.1429 | 17 weeks and 1 day |
| 180 | 25.7143 | 25 weeks and 5 days |
| 365 | 52.1429 | 52 weeks and 1 day |
Common day counts and their exact week equivalents.
Frequently asked questions
How many weeks is 90 days?
90 days is 12 weeks and 6 days, or 12.857 weeks expressed as a decimal. You get this by dividing 90 by 7: 90 / 7 = 12.857. The whole-week part is 12, and the remainder is 90 - (12 x 7) = 6 days.
How many days is a week and a half?
1.5 weeks is 10.5 days (1.5 x 7). In practice this is often rounded to 10 or 11 days depending on whether you count the half-day.
How many weeks is 100 days?
100 days is 14 weeks and 2 days, or 14.2857 weeks. The formula is 100 / 7 = 14.2857. To find the remainder: 14 complete weeks cover 98 days (14 x 7), leaving 100 - 98 = 2 extra days.
How many weeks is 180 days?
180 days is 25 weeks and 5 days, or approximately 25.714 weeks. It is also roughly 5.9 months and about 0.493 years (just under half a year).
What is 365 days in weeks?
365 days equals 52 weeks and 1 day, which is why a non-leap calendar year has 52 full weeks plus one extra day. A leap year of 366 days is 52 weeks and 2 days.
Is a month exactly 4 weeks?
No. Four weeks is exactly 28 days, but most calendar months are 30 or 31 days (28 days for February in non-leap years). The average Gregorian month is 30.4375 days, which is about 4.348 weeks - so saying "a month is 4 weeks" introduces a small but cumulative error over multiple months.