I am trying to, in Excel, compare two samples of the same material that are different sizes to compare the relative defect rate. Can anyone help me set that up?

You want to use a 2 - Proportions test. Excel does not have this test in their Analysis add-in, but the formulas are fairly simple to replicate in Excel. See the Normal approximation test or Fisher's exact test for reference.

You want to use a 2 - Proportions test. Excel does not have this test in their Analysis add-in, but the formulas are fairly simple to replicate in Excel. See the Normal approximation test or Fisher's exact test for reference.

I tried using the formulas you suggested and I have a feeling I did not clearly describe what I am trying to accomplish. Two independent groups tested their own sample size (based on their group's sampling rules) of the same data for process failures. Group 1 has substantially larger sample size than Group 2; almost 20 times in size. Both groups then calculate the defect rate (findings/sample size) of the found failures; both defect rates because of the sample sizes are different and I need to find a way to show if the defect rates would be the same if the sample sizes were the same

The difference in sample size will affect the width of the confidence interval around each estimate, but should not affect the estimate itself. The methods that I referenced take the different sample sizes into consideration.