Here are some simplified brewing calculators that may help you when you are brewing.
%ABV Calculator (uses HMRC conversion factors)
This calculator below assumes you are using a hydrometer to measure the gravity/density of your beer. If you use a refractometer, please convert your final gravity (FG) using the correction calculator first.
Hydrometers measure the density of the liquid. The more sugars dissolved, the higher the density. The less sugars dissolved, the lower the density. Water has a specific gravity of 1.000. In other words, its density is 1.00g/ml. As sugar is converted to alcohol (which has a lower density than water), the gravity of the beer reduces. Using the difference between the start and end gravity, a calculation can be performed to calculate the %ABV.
Refractometer to hydrometer correction (using SG)
If you are using a refractometer to measure your original and final gravity (measured in SG units), your original gravity (OG) will be identical to that measured using a hydrometer. However refractometers measure the refractive index of the liquid and are calibrated to be based on the sugar content in the beer. More sugar gives a higher refractive index. However, because alcohol also changes the refractive index of the liquid, this will interfere with your final gravity measurement. This calculator will allow you to correct for alcohol content and get a true final gravity (as if you'd used a hydrometer).
Convert between Plato (Brix) and SG
Depending on your hydrometer or refractometer, you will be given measurements in either Plato, Brix or SG. Plato is common for beer brewers and Brix is common for winemakers. For beer purposes (and the %ABV involved), they are pretty much the same, so can be used interchangeably. Plato/Brix is commonly found on refractometers. SG is a density measurement normally found on hydrometers (more common for homebrewers).
Priming sugar calculator (batch prime for bottling)
Now your beer has finished fermenting, you're ready to package it (ready for drinking in a few weeks). Depending on the style of beer and packaging used, you can use the calculator to give you a suggested mass of priming sugar. Too little and your beer will be flat and lifeless, too much and you could have exploding bottles and a lot of mess! The priming sugar will also be fermented into alcohol and this will increase the %ABV - something a lot of people forget! This calculator will also tell you what to expect.
If cask conditioning, we'd recommend a maximum carbon dioxide volume of 1.4.
If priming a firkin (40.8L approx): 50g table sugar. For a pin (20.4L): 30g. For a 5L minikeg: 18g.
If bottling, use the calculator below.
Dilution calculator (beer OG is too high and you want to lower to a set value)
This calculator will tell you how much additional water you need to add to dilute the wort to the desired OG.
Brewing salt addition calculator
Rather than try to squeeze this on to a web page, we've included a link to a Google Sheet (Spreadsheet) that will help you adjust your water Chemistry. You will need to make your own copy (File > Make a copy) if you have a Google Account, or download the file as an Excel spreadsheet to use offline.
If you want to read more about the Chemistry involved and how this calculator works, please check out the document in the Chemistry section.