# How to calculate daily interest at different rates each day? [closed]

I have the following issue:

I need to calculate the daily income of a financial application over a period based on a percentage of a daily financial index. The problem is that for each day, this index has a different value. For example:

Date     value
Apr-1    0,048089%
Apr-2    0,045442%
Apr-3    0,041886%
and so on...
Apr-31   0,035450%


On April 1, the initial value of the investment was $1,000. How much will the total be on April 31st? Is there a way to get the final value using a single formula? The way I do today, I need to calculate the day-to-day balance. • 30 days have September, April, June and November. So by the time April 31st turns up I guess it will have accrued a lot of interest. – CashCow Oct 7 '19 at 10:42 ## 1 Answer if the values are calculated using discrete compounding, you could do the following. Formula in Excel: =PROD(1+A1:A31)*1000 one line in R prod(1+df$value)*1000

A word of warning: if you are using this to compound interest rates other than overnight rates, you are on the wrong track.

Anyway, I will vote to close the question since its too basic.

• so basic you forgot to apply day-count convention / year fraction. – CashCow Oct 7 '19 at 10:44