This calculator gives you an estimate the alcohol %age, the original and the final gravity of your beer. The dial at the top, and the readout text beside it is based on the above "body table".
All you have to do is enter the weights of your recipe ingredients (in the white fields above) and click "submit".
Hint: Your "Tab" key will move to the next field for you (rather than reach for the mouse for each entry) and "Shift" + "Tab" will move backwards a field.
If you are wanting to make a beer of a specific strength or final SG, you can also alter the ingredient weights in the calculator to work out the combination that will produce the beer you want. Just alter the amount(s) and click on submit again.
Note that the figures are only a guide. Final gravity can vary with the use of different yeast strains. Also the use of enzymes in your beer will change your final gravity. DO NOT USE THESE FIGURES TO ESTABLISH END OF FERMENTATION... They are estimates only and may vary.