Calculator
Plato ↔ specific gravity converter
What is this gravity in degrees Plato?
Both scales describe the same thing — how much dissolved material is in the wort — from different traditions. Specific gravity expresses it as a ratio against water and is standard in Britain and America; degrees Plato express it as an approximate percentage of sugar by weight and are standard in continental Europe and in most commercial brewing.
Converting between them is routine, because recipes, yeast documentation and equipment specifications do not agree on which to use. A rough rule is that one degree Plato is about four gravity points, which is close enough for mental arithmetic and diverges at high gravity — which is exactly where a real conversion is worth doing.
Result
- Plato ↔ specific gravity converter11.9°P
Working
°P = −616.868 + 1111.14 × SG − 630.272 × SG² + 135.997 × SG³
| Step | Expression | Value |
|---|---|---|
| Conversion | cubic polynomial | 11.912 |
What it means
Czech and German brewing quote strength in degrees Plato — a "12°" beer is around 1.048 SG. Dividing Plato by four gives a rough ABV estimate for a typical attenuation.
Worked example
The example above starts from these values. It is rendered on the server, so the formula, assumptions and limitations are all present whether or not you change anything.
- Result11.9°P
Inputs
| Gravity | 1.048 |
|---|
How it is calculated
°P = −616.868 + 1111.14 × SG − 630.272 × SG² + 135.997 × SG³
What each term means
| SG | Specific gravity, the density of the wort relative to water |
|---|---|
| °P | Degrees Plato — grams of sucrose per 100 g of solution |
Step by step
| Step | Expression | Value |
|---|---|---|
| Conversion | cubic polynomial | 11.912 |
What this assumes
- The measurement is of wort or beer, whose dissolved solids behave close enough to sucrose for the approximation to hold.
Where it stops being reliable
- Both directions are polynomial approximations to a lookup table, not exact conversions. They are accurate to well under 0.1 °P across normal wort strengths and degrade outside roughly 1.000–1.130.
- Plato is defined against sucrose. Wort is not sucrose, so the figure is a convention rather than a literal sugar concentration.
What the number means
Czech and German brewing quote strength in degrees Plato — a "12°" beer is around 1.048 SG. Dividing Plato by four gives a rough ABV estimate for a typical attenuation.
Empirical approximation. A curve fitted to measured data. It has real error bars, and it is frequently quoted as though it were exact.
Sources: ASBC Plato tables.