Beer Brewing Original Gravity Calculator

Work out beer brewing original gravity instantly with clear inputs, formula shown and shareable results.

About Beer Brewing Original Gravity Calculator

Gravity points are grain weight times extract potential times brewhouse efficiency, divided by batch volume; adding those points to 1.000 gives the original gravity. Efficiency is the term brewers most often get wrong, and since it multiplies directly into the gravity, a 10 point efficiency error moves the finished beer by about half a percent ABV.

Formulas

Gravity points

points = grain kg x extract potential x efficiency / batch litres

Original gravity

OG = 1 + points / 1000

Worked example

With the default values below, Beer Brewing Original Gravity Calculator returns Original gravity of 1.0502. Change any input above and every figure here is recalculated in your browser.

Inputs used

Total grain billminimum 0.1 kg: 5 kg
Extract potentialminimum 100 pts L/kg: 308 pts L/kg
Batch volumeminimum 1 L: 23 L
Brewhouse efficiencyaccepts 20–100 %: 75 %

Results

Original gravity: 1.0502
Gravity points: 50.2
Degrees Plato: 12.38
Expected ABV at 1.011 final gravity: 5.15%

Step by step

1Values used
2Gravity points
3Original gravity
4Original gravity= 1.0502
5Gravity points= 50.2
6Degrees Plato= 12.38
7Expected ABV at 1.011 final gravity= 5.15

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Beer Brewing Original Gravity figure worked out?

points = grain kg x extract potential x efficiency / batch litres. Gravity points are grain weight times extract potential times brewhouse efficiency, divided by batch volume; adding those points to 1.000 gives the original gravity.

Why does this matter?

Efficiency is the term brewers most often get wrong, and since it multiplies directly into the gravity, a 10 point efficiency error moves the finished beer by about half a percent ABV.

What do I need to enter?

Enter total grain bill, extract potential, batch volume, brewhouse efficiency. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.