I am really struggling to write a formula that will give me how many weeks stock I have based against a monthly forecast and current stock level, It has to take in to account the rest of the monthly forecast to give me a weeks cover figure.Trying to maintain 8 weeks cover through the year, so need something that will highlight when stock cover drops below 8 weeks
jan feb mar apr may
A1 Forecast 10 10 10 10 10
A2 Stock 100 90 80 70 60 50
A3Coverage wk ?

I know based on 90 stock and forecast of 9 weeks, but changes to stock forecast need a way of doing it

Thanks!