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Is there an equation or relation to describe how much sugar is to be added to water to obtain a liquid with a specific gravity?

In This question, for example, it is mentioned that "1 lb in 1 gallon is 1.046" - but is there a known scale? Or is extrapolating from this the only way?

Bonus points for metric units, double points for referenced answer!

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To add up on Denny's answer, the density of a solution of sugar and water is (quasi)linear in the range we use in homebrewing (e.g. between 1 and 1.2). (see graph below [0] where concentration in wt% is equivalent to degree Plato)

density vs concentration

Using this graph, you could make a sugar solution with known density by adding sugar into water. E.g. a 5°Plato (5 wt%) solution would roughly be 5g of sugar in 95g of water.

[0] https://www.engineeringtoolbox.com/density-aqueous-solution-organic-sugar-alcohol-concentration-d_1954.html

  • Wonderful, exactly what I was looking for. Thanks! – Mike Meyers May 22 '18 at 9:49
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Sugar has about 45 ppg. That's gravity points per pound per gallon. So, one lb. of sugar in one gal. of water will give you a specific gravity of about 1.045. That is the known scale. 2 lb. in 1 gal. gives you 1.090, etc.

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    Is it perfectly linear, though? Could be non-linear with just this point being a commonly known one – Mike Meyers May 21 '18 at 15:52
  • yes, it is perfectly linear. Why wouldn't it be? – Denny Conn May 21 '18 at 16:47

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