percentage calculation from cumulative totals

bearingman, I don't think the problem lies with Excel, but rather with understanding what you are calculating.

Maybe it will help if you visualise the values in a chart. Attached see a line chart with Accumulated Target and Accumulated Savings as two lines.

Note that the gap between the two lines gets less and less. That's what your formula shows as a percentage. You start off with 21% above target, and towards the end you are around 14% above target.

Since your formula calculates against the accumulative values, you see very little change from one value to the next.

The second chart shows the lines for the daily values. Here, you see a more dramatic difference between the day to day values.

I assume that you really want to calculate a performance based on the daily values rather than the accumulated ones.

Anything can be calculated. But you must specify clearly what you want to calculate before you can judge if a result is wrong or not.

If you want to calculate the difference between the daily target and daily savings, then I suggest you use a formula that actually references these cells, like

=(A3-B3)/B3

See attached file, column F.

cheers,