Wort Gravity Units & Sugar Content Calculator

This calculator translates a single hydrometer reading into every unit brewers care about: gravity points, degrees Plato (effectively Brix), and the approximate dissolved sugar in grams per litre. Add a final gravity and it also reports apparent attenuation.

How it works

Specific gravity (SG) is the density of the wort relative to water. Pure water is 1.000; dissolved sugar raises it.

Gravity points are just the decimal part scaled up:

points = (SG - 1) * 1000

So 1.050 is 50 points.

Degrees Plato is the percentage of sugar by weight, obtained from the standard cubic approximation:

Plato = -616.868 + 1111.14*SG - 630.272*SG^2 + 135.997*SG^3

Dissolved sugar (g/L) combines Plato (mass percent) with wort density. Since 1 L of wort weighs SG kilograms (1000 * SG grams), the sugar mass is:

sugar_g_per_L = Plato/100 * 1000 * SG

A 1.050 wort is about 12.4 Plato, giving 0.124 * 1000 * 1.050 ≈ 130 g/L of dissolved sugar.

Tracking fermentation

If you supply a final gravity (FG), the tool reports apparent attenuation, the percentage of gravity points the yeast removed:

apparent attenuation = (OG_points - FG_points) / OG_points * 100

For an OG of 1.050 (50 pts) finishing at 1.010 (10 pts), that is (50 - 10) / 50 = 80% — a healthy, well-fermented beer.

Why each unit matters in practice

Brewers encounter all three units in different contexts, which is why having them side by side is genuinely useful.

Specific gravity is what your hydrometer reads directly. It is the standard measurement for homebrew and most commercial recipe software. However, the numbers like 1.050 are awkward to do arithmetic with — adding two gravities or scaling a recipe requires the points form.

Gravity points (also written as GU, gravity units) are used whenever you need to do recipe maths. For example, if you know your grain contributes 36 points per pound per gallon, you can multiply points by volume and divide by extraction to find the grain weight you need. Points add and scale linearly; SG fractions do not.

Degrees Plato is the unit of choice in professional brewing and on commercial yeast datasheets. Most yeast manufacturers state their attenuation and nutrient requirements in Plato. A beer described as “12 Plato original gravity” is a medium-strength lager roughly equivalent to 1.048 SG.

Worked example — scaling a recipe

Suppose you have a recipe written for 20 L of 1.060 (60 points / 14.7 Plato) wort but you want to brew 25 L. The points form makes scaling obvious: you need 25% more extract, so your grain bill scales by the same factor. The Plato value stays the same because concentration is what Plato measures, not total quantity. Only the gravity points-times-volume (the total extract mass) changes.

Entering 1.060 into this tool shows approximately 148 g/L of dissolved extract — so 20 L contains about 2,960 g of sugar, and 25 L would require about 3,700 g, a direct and easy check on your recipe scaling.

Notes

• The Plato polynomial is accurate across the normal brewing range (roughly 1.000 to 1.130).
• “Sugar content” here is the total dissolved extract, which in real wort is mostly fermentable sugars plus some unfermentable dextrins — Plato cannot distinguish the two.
• Always temperature-correct your hydrometer reading first; most hydrometers are calibrated at 20°C. At higher temperatures wort appears less dense, giving a falsely low reading; use a hydrometer temperature-correction chart or a refractometer correction table for mid-fermentation readings.
• All math runs locally in your browser; nothing is uploaded.