This is very much experimental! As I often create calculators for classes it seems a shame not to share them, so they will be varied, and as needs must for my own purposes but you never know, they might just help you!
Clicking the buttons will download a spreadsheet in Excel. In time I hope that I can get the calculator to open on site and/or provide versions that people without excel can access.
Learning curve in progress!
May not work on your phone! Try the PC
You will need to click 'enable editing' to use the caculator