Convert annual interest rate to weekly

[shreksbro]

Hi mathemagicians, I am creating a kind of calendar spreadsheet with a row for each week, to budget weekly payments and deposits and to forecast savings etc.

I have an "interest rate" column next to the savings account column, where I can state (and edit) the annual interest rate in effect - but I don't know how to correctly convert it into a weekly rate for the purposes of calculating and compounding the interest.

I have had limited success finding an answer with Google, but I'm afraid a lot of the advanced mathematics goes over my head. I know exponentials are involved, but the mere mention of the word brings me out in a cold sweat and trembles.

Can someone dumb it down for me and give me an Excel formula that will do it? If I can get from an annual rate in A1 to an equivalent weekly rate in A2 I can do the rest. I realise that my calculations won't precisely match the reality if changes are made within an interest calculation period, but it should be accurate enough for my purposes.

Many thanks!!

[bebo021999]

How about = A1/360*7
Or = A1/52
It depends on your local practice.

[shreksbro]

Hi, thanks, but isn't it a bit more complicated than just dividing the annual rate by 52 weeks, due to the interest compounding each week?