solved it, was a problem with my cross sheet referencing. The formula I needed was =LOGEST(y,x) What I was trying to do was use the formula of the exponential to predict a value of Y where X is known (if it means anything its gel filtration [aka size exclusion chromatography]) The reason I'm not just copying it down is because the calibration curve is unique to the piece of equipment being used, and it has to be calibrated with standards. As I will be using many of these things, and my co workers also use some of their own, I wanted to design a spreadsheet that allows you to input the calibration data and it will do the rest. Then on the main sheet you have a box into which you put your experimentally determined X value and it will predict Y. You also have to re-calibrate these things quite frequently to keep them accurate so in the long run i wanted it to save me time as well. I will be making another one for something else next week. Lucky for me its a simple linear regression so much more simple to do.