Conversion formula

The conversion factor from days to weeks is 0.14285714285714, which means that 1 day is equal to 0.14285714285714 weeks:

1 d = 0.14285714285714 wk

To convert 21 days into weeks we have to multiply 21 by the conversion factor in order to get the time amount from days to weeks. We can also form a simple proportion to calculate the result:

1 d → 0.14285714285714 wk

21 d → T_(wk)

Solve the above proportion to obtain the time T in weeks:

T_(wk) = 21 d × 0.14285714285714 wk

T_(wk) = 3 wk

The final result is:

21 d → 3 wk

We conclude that 21 days is equivalent to 3 weeks:

21 days = 3 weeks

Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 week is equal to 0.33333333333333 × 21 days.

Another way is saying that 21 days is equal to 1 ÷ 0.33333333333333 weeks.

Approximate result

For practical purposes we can round our final result to an approximate numerical value. We can say that twenty-one days is approximately three weeks:

21 d ≅ 3 wk

An alternative is also that one week is approximately zero point three three three times twenty-one days.

Conversion table

days to weeks chart

For quick reference purposes, below is the conversion table you can use to convert from days to weeks