I got interested in the quantitative aspects of exposure calculation in photography. After poking around a little, I learned enough to create the spreadsheet I'm making avialable here.
The parameters of interest are f-stop (f), exposure time (t), exposure value (EV), and sensitivity (ISO). There are sheets in the spreadsheet designed to calculate each of these values given the others. There is another sheet within the spreadsheet that can be used to convert EV to the more technical parameter of luminance.
I have a version of this spreadsheet on a PDA. The version I carry has an additional worksheet in it which correlates EV values to narrative descriptions of EV values, which I found on Fred Parker's well-known site:
Fred Parker's Ultimate Exposure Computer
That site is a good learning experience in general. He encourages printing, carrying, and using his tables but not redistributing them, so I've taken that worksheet out of my own spreadsheet here.
This unfancy spreadsheet is in MS Excel format. The units are the standard used in photography except as indicated. The input fields are shaded yellow. I've left the worksheets all set up at Sunny 16: A bright sunny day is about EV 15, and f16 at t = 1/125 works well at ISO 100. The spreadsheet being exact, and Sunny 16 being an 'analog' rule, the numbers vary a touch. Good luck!