Hello.

I hope my question is a simple one. Basically I am making a wine at the moment and due to a schoolboy error I made just
over 28 litres (just over 6 UK Gallons) rather than 23 litres. That meant that I had to hold back 2.5 litres of water
(from a final 28 gallon must) until I removed the bag of fruit. The original recipe is all in the correct ratios.

My OG was about 1.124. Is there a simple way of calculating what the Specific Gravity at the start would have been
including the extra 2.5 litres? I imagine it would be as simple as:

((Original SG - 1) * (original volume of liquid/final volume of liquid))+1

(0.124 * (25.5/28))+1 = 1.113

Is that right or is there an obvious anomaly there?

Many thanks, Jim