Alphabet association to a number for use as column number in vlookup for excel...sliding

I am always counting on my fingers the number for the column in vlookup in excel and think there must be a better way...if I start my column at c, then c=1 and have to go to p, then the column number would be 14 for the function. is there some type of chart that you can help me with that I can share with my co workers that will offer the answer depending on what letter starts the formula?

does this make sense?