Using Brewtarget To Calculate Water And Hop Quantities

When planning beer recipes it’s useful to be able to quickly see the effect of any changes, but the many variables make it an unwieldy manual calculation.

As an alternative I’ve recently been testing Brewtarget, a free piece of brewing software and this is what I found.


I discovered Brewtarget after reading an article on Mash Sparge Boil, a home brew blog that’s no longer active. It seemed as though it covered most beer calculations with the added attraction of being free.

You can download it here.

To put it to the test, I tried it on a recent brew. I used the software to determine the water quantity for the brew in a bag mash, and to adjust the hops to the required bitterness levels.

After I explain this in more detail you’ll have a good idea of whether it’d be useful for you or not.

Overview of Brewtarget

The programme is easy to navigate. Most options are available from the main screen.


After starting a new recipe, you add the ingredients through the boxes along the bottom. First the malt…

brew target fermentables malt

Next the hops…

brew target hops

Finally the yeast…

brew target yeast

You can also include herbs and spices or other ingredients if you’re using them.

Then you input the mash details. There are some typical mash profiles built-in, or you can create and save your own as I did.

brewtarget edit mash

You can go into a lot of detail such as starting temperature of grain, temperature of mash tun and more. Typical values are pre-set so Brewtarget makes sensible assumptions if you don’t want to enter everything.

brew target mash settings

As you add things the calculations update automatically. You get readouts for gravity, bitterness and colour, as well as an indication of whether the flavour will be malty, hoppy or balanced.

brewtarget mild recipe summary

At this point I started tweaking.

Water Calculations

One of the hardest things to predict with brew in a bag is the amount of wort you’ll end up with in the fermenter. I typically achieve 12 – 16 litres starting the mash with 21 litres.

To get a better handle on this, I’ve calibrated my fermenter to measure precisely how much beer there is after the boil. Brewing software indicates what to start with.

The test recipe was for a strong beer, so I was limited by the amount of malt I could fit in the brew pot. Setting the target batch to 10 litres gave me 6kg of malt to achieve an original gravity of 1.114 (you can see that displayed on the larger images below).

In Brewtarget you can adjust the mash volume and see the effect on the calculated batch size. As you can see, 12 litres at the start would yield a mere 2.6 litres of beer.

brewtarget mash start volume wrong

The calculations are based on things like length of boil and quantity of water lost to grains.

Increasing the start volume to 19 litres brought me close to the target of 10 litres.

brewtarget mash start volume

The resulting brew was extremely close to the target. I bucketed 9.5 litres, impressed with the accuracy of the Brewtarget prediction.

Hop Calculations to Achieve the Desired Bitterness

Hop bitterness is an important factor in any beer and should be considered in every brew. The recipe I was following specified IBU targets for each of the hop additions.

I manually translated the quantities from the recipe to match the alpha-acid values of my hops, and to take into account the smaller batch size.

The software took these numbers and outputted a bitterness value lower than that specified in the recipe.

brewtarget hops wrong

It’s easy to change the amount of each hop variety until the IBUS are back on target.

brewtarget hops recipe

The prediction is now for an extra hoppy beer, with the IBUs as per the recipe and my hop additions shown below.

If I have reservations they’re not about this particular programme, which does the intended job well, but about brewing software in general. Although it’s useful, it’s only in conjunction with your experience.

If you’re looking for a free beer calculator, Brewtarget is worth a try.

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  1. Cliff

    Hi John. I am researching full grain brewing (from New Zealand) and find your articles well written,well illustrated and extremely informative and helpful. Thank you for your time ,effort and generosity making the articles free to view.

    Cheers -Cliff.

    • John

      Hi Cliff,

      Thanks for visiting and for the comment. I appreciate it.

      I’m glad you like the articles – I enjoy producing them and it’s great if they’re of interest and use to others.

      Good luck with your brewing!

  2. Jose carlos salles

    Amigo, sou brasileiro, pouco entendo de inglês. Gostaria, se possivel, se você me informasse como fazer a conversão para litros. Obrigado.

    • John

      Em Brewtarget? Você vai a “Tools”, “Options”, “Units”, e clique em “Use SI units”.

      É isso que você quer dizer?

      Aqui estão algumas tabelas de conversão também.

      (Eu não falo Português, desculpe a tradução informatizado.)