How do you convert specific gravity to Plato?
Both numbers describe how much sugar is dissolved in your wort. Specific gravity is density relative to water (1.048 is 4.8% denser); degrees Plato is the sugar as a percentage by weight (12 °P is 12 g of extract in every 100 g of wort). Brewers swap between them with a rule of thumb — divide the gravity points by 4: 1.048 is 48 points, so about 12 °P — and it's close: the exact figure is 11.9 °P. The exact conversion is a fitted curve (ASBC), and its inverse:
°P = −616.868 + 1111.14·SG − 630.272·SG² + 135.997·SG³
SG = 1 + °P ÷ (258.6 − (°P ÷ 258.2) × 227.1)
The rule of thumb is exact at 1.040 (10.0 °P) and drifts as wort gets denser, because each extra percent of sugar adds a little less density than the last. Below 1.050 the error is a rounding error; by barleywine gravity it's more than a full degree:
| SG | Exact °P | Points ÷ 4 | Rule minus exact |
|---|---|---|---|
| 1.020 | 5.08 | 5.00 | −0.08 |
| 1.030 | 7.56 | 7.50 | −0.06 |
| 1.040 | 9.99 | 10.00 | +0.01 |
| 1.050 | 12.39 | 12.50 | +0.11 |
| 1.060 | 14.74 | 15.00 | +0.26 |
| 1.070 | 17.06 | 17.50 | +0.44 |
| 1.080 | 19.33 | 20.00 | +0.67 |
| 1.090 | 21.57 | 22.50 | +0.93 |
| 1.100 | 23.77 | 25.00 | +1.23 |
| 1.120 | 28.06 | 30.00 | +1.94 |
ASBC polynomial vs. points ÷ 4, from this page's engine. Shaded where the shortcut is off by half a degree or more.
Specific gravity to Plato conversion chart
For a brew-day sheet or the fridge door: SG, points, °Plato (= °Brix for wort), °Baumé and the grams of dissolved sugar in each liter.
| SG | Points | °P / °Bx | °Bé | Sugar g/L | SG | Points | °P / °Bx | °Bé | Sugar g/L | |
|---|---|---|---|---|---|---|---|---|---|---|
| 1.000 | 0 | 0.0 | 0.0 | 0 | 1.068 | 68 | 16.6 | 9.2 | 177 | |
| 1.004 | 4 | 1.0 | 0.6 | 10 | 1.072 | 72 | 17.5 | 9.7 | 188 | |
| 1.008 | 8 | 2.1 | 1.2 | 21 | 1.076 | 76 | 18.4 | 10.2 | 198 | |
| 1.012 | 12 | 3.1 | 1.7 | 31 | 1.080 | 80 | 19.3 | 10.7 | 209 | |
| 1.016 | 16 | 4.1 | 2.3 | 41 | 1.084 | 84 | 20.2 | 11.2 | 219 | |
| 1.020 | 20 | 5.1 | 2.8 | 52 | 1.088 | 88 | 21.1 | 11.7 | 230 | |
| 1.024 | 24 | 6.1 | 3.4 | 62 | 1.092 | 92 | 22.0 | 12.2 | 240 | |
| 1.028 | 28 | 7.1 | 3.9 | 73 | 1.096 | 96 | 22.9 | 12.7 | 251 | |
| 1.032 | 32 | 8.0 | 4.5 | 83 | 1.100 | 100 | 23.8 | 13.2 | 261 | |
| 1.036 | 36 | 9.0 | 5.0 | 93 | 1.104 | 104 | 24.6 | 13.7 | 272 | |
| 1.040 | 40 | 10.0 | 5.6 | 104 | 1.108 | 108 | 25.5 | 14.1 | 283 | |
| 1.044 | 44 | 11.0 | 6.1 | 114 | 1.112 | 112 | 26.4 | 14.6 | 293 | |
| 1.048 | 48 | 11.9 | 6.6 | 125 | 1.116 | 116 | 27.2 | 15.1 | 304 | |
| 1.052 | 52 | 12.9 | 7.2 | 135 | 1.120 | 120 | 28.1 | 15.5 | 314 | |
| 1.056 | 56 | 13.8 | 7.7 | 146 | 1.124 | 124 | 28.9 | 16.0 | 325 | |
| 1.060 | 60 | 14.7 | 8.2 | 156 | 1.128 | 128 | 29.7 | 16.5 | 335 | |
| 1.064 | 64 | 15.7 | 8.7 | 167 | 1.132 | 132 | 30.6 | 16.9 | 346 |
Unfermented wort or must at the hydrometer's calibration temperature. °Oechsle equals the points column. °Brix from a refractometer must be divided by its wort correction factor (~1.04) before using this chart.
Are Plato and Brix the same thing?
For brewing purposes, yes — Brix, Plato and the older Balling scale all define 1° as 1 gram of sucrose per 100 grams of solution; they differ only in how carefully the reference tables were measured, and the difference is in the third decimal place. Wine and cider people say Brix, brewers say Plato, and Germans use Oechsle (which is just the gravity points). Convert freely between the scales.
A hydrometer reads density directly, so its Plato scale is Plato. A refractometer measures how much the wort bends light, calibrated for pure sucrose — and wort's mix of maltose and dextrins bends light a little more than sucrose does. Its "12 °Bx" is really about 11.5 °P once you divide by the wort correction factor (1.04 is typical; calibrate your own). Treat the raw Brix as Plato and you'll write down 1.048 for a wort that is actually 1.046 — two points, which is exactly the size of "I don't know why I always miss my OG". The calculator's "Brix — refractometer" option applies the factor for you.
Why gravity points, and how much sugar is that?
Brewers strip the "1.0" and talk in points — 1.052 is "52" — because points add up: a grain's extract potential is quoted in points per pound per gallon, brewhouse efficiency is a ratio of points, and hitting a target is "four points short". Points are what the ABV formula multiplies and what your efficiency is calculated from. And because a degree Plato is a weight percentage, it tells you something SG hides: how much sugar is actually in the kettle.
12.4 °P means 12.4 g of extract per 100 g of wort, and a liter of 1.050 wort weighs 1,050 g — so 130 g/L. A 5-gallon batch is carrying about 2.5 kg (5.4 lb) of dissolved sugar, which is why the extract-brewing rule "a pound of DME per gallon gives you 1.044" is not a coincidence.
What about after fermentation?
None of these formulas know about alcohol. They convert a sugar-water density into a sugar percentage, and once ethanol (lighter than water) is in the mix, a hydrometer's 1.010 does not mean 2.6% sugar — it's an "apparent" extract, useful for ABV and attenuation, not a sugar measurement. A refractometer is worse off: alcohol bends light too, so its post-fermentation Brix needs a dedicated correction using the original gravity, not this converter. Convert your OG here with confidence; for FG, use the reading as-is in the ABV calculator and leave the sugar-percent interpretation alone.