http://www.thehomebrewforum.co.uk/viewtopic.php?f=40&t=14076 The picture 6 posts down should do you.
If you would like the maths, there are 2 ways I believe
1) Say you have
Sugar 1000g =1Kg
Raisins 500g*.666 = 333g (Times the weight of raisins by 0.666 to get the amount of sugar they contain approx)
= 1333g
Divide by 4.5L for 1 gallons that 296 in a Litre,
100 grams in a litre gives 36 points so 2.96 x 36 = 1.107
But that is sugar
to the gallon so you have 1 Gallon of water and you have now added 1333g of sugar to it increasing the volume so therefore decreasing the reading slightly.
2) To do sugar
in the gallon, ie having 1333g of sugar and adding water up to the gallon mark so using less water I use ferm calc
http://web2.airmail.net/sgross/fermcalc/fermcalc_applet.html.
Click on the sugar tab then select the option "Specify the H20/Sugar additions". Now 1Kg of sugar displaces 600ml of water so you know that the maximum water you will be using is 3.9, so enter 3.9 Litres in starting volume then say 1.3kilograms or 1333grams in the sugar. Check your resulting volume, it will probably be over 4.5 Litres so now bring your staring volume down number by number until you get the resulting volume more or less on 4.5 L and then switch your resulting SG from specific gravity to potential alcohol and there you have it.
Hope I have explained that ok, if not then ask.
And more experienced members, have I got that correct the In and the To gallon part?
HLA91