HesapHanem

Plato to Specific Gravity

Turn a °Plato reading into specific gravity for your brew.

How it is calculated

The conversion uses a common brewing approximation: SG = 1 + P ÷ (258.6 − (P ÷ 258.2) × 227.1), where P is the reading in degrees Plato (grams of dissolved extract per 100 g of wort). The result is a dimensionless specific gravity relative to water at 1.000, shown with three decimals. P must be 0 or more and below 100; values outside that range give no result, and 0 gives 1.000. The formula is an approximation, and it assumes the reading is for a sugar solution at the calibration temperature of your instrument. Hydrometers and refractometers have to be temperature-corrected before you enter the number here.

Worked example

Wort measures 12 °P. First the correction term: 12 ÷ 258.2 = 0.04647, multiplied by 227.1 gives 10.55. Subtract from 258.6: 258.6 − 10.55 = 248.05. Then 12 ÷ 248.05 = 0.04838. Add 1 and the specific gravity is 1.048. The quick shortcut of 1 + 12 × 0.004 gives the same 1.048 at this strength, and the two drift slightly apart at higher gravities such as 20 °P.

Try this example →

Common mistakes

  • Typing a specific gravity such as 1.048 into the Plato field. The tool expects degrees Plato, about 12 for a typical ale, not the SG value.
  • Entering a point value (48) or °Brix reading as if it were Plato. Brix and Plato are close but a refractometer reading from fermenting wort needs its own correction.
  • Ignoring sample temperature. A hot wort reading gives a lower SG than the same wort cooled to the calibration temperature.
  • Using the result for the finished beer. Alcohol lowers the density, so a final-gravity reading from a hydrometer cannot be converted by this simple formula without correction.
  • Rounding the SG to two decimals. Three decimals matter for gravity points and for later ABV calculations.

About this calculator

Degrees Plato (°P) and specific gravity (SG) both measure the sugar content of wort or must, just on different scales — Plato reads as roughly the percentage of dissolved solids by weight, while specific gravity compares the liquid's density to water (1.000). A common approximation is SG = 1 + (°P / (258.6 − ((°P / 258.2) × 227.1))), and a rough shortcut many brewers use is SG ≈ 1 + (°P × 0.004) for everyday values.

Brewers, distillers and winemakers move between the two scales constantly because European and professional brewing equipment (refractometers, some hydrometers) is often calibrated in Plato, while most homebrew recipes, especially in the US, are written in specific gravity — getting the conversion right matters directly for calculating original gravity, final gravity and therefore ABV and attenuation.

Was this helpful?

You can pick up to 3 reactions.

Comments

  • Be the first to comment.

Popular calculators

Loan Calculator

Monthly payment, total interest and full amortization schedule.

Percentage Calculator

Percent change, percent of, and ratio calculations.

Discount Calculator

Calculate final price, savings, and discount amount.

BMI Calculator

Body mass index from height and weight (metric or imperial).

Age Calculator

Compute your exact age in years, months and days from a birth date.

Compound Interest Calculator

Calculate the final amount and interest earned with compounding.

All Calculators