Work out beer brewing original gravity instantly with clear inputs, formula shown and shareable results.
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.
Gravity points
points = grain kg x extract potential x efficiency / batch litres
Original gravity
OG = 1 + points / 1000
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.
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.
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.