Calibration Brew Day: What’s Your Brewhouse Efficiency?

After listening to a Brulosophy podcast episode on efficiency, I felt compelled to do something I actually haven’t ever done. I decided it was time to calibrate my brew system. Every system I’ve owned has had a profile in my brewing software, but I’m a data nerd and I thought it would be fun to get some cold, hard data on my actual brewhouse efficiency and my mash efficiency.

Using the ‘default’ equipment profile in your software

I brew on the BrewTools B40 Pro electric brewing system and use the Brewfather brewing software. Brewfather has a pretty decent BrewTools B40 equipment profile and that is what I had been using since I purchased this brewing system. But there are a few variables that can affect your efficiency numbers. Some of these variables are, but not limited to:

Tubing length and diameter

You don’t really know what the tubing situation was when the equipment profile creator created that profile. You can assume it wasn’t anything extreme and that the numbers will get you ‘in the ballpark’, but if you really want to dial in your system you need to run through a calibration brew day. Long tubing / hose runs can cost you multiple liters of precious wort.

Type of chiller

This kind of tries into the tubing / hose size thing too. I use a counterflow chiller with my brewing system and a few lengths of tubing to connect the chiller to the kettle. Different counterflow chillers retain a certain amount of wort that isn’t necessarily going to all end up in your fermenter. Plate chiller users will have fewer losses than counterflow chiller users. If you’re an immersion chiller user then you’re more than likely not going to have any chiller losses.

Boil off rate

This is a variable that A LOT of brewers don’t pay attention to and it’s super easy to calculate. You don’t even need to brew a batch! And you really don’t even need to boil for a full hour. If you’re bored one day just fill up your boil kettle with what would be your usual volume of wort and boil the water for 15 minutes. Measure the loss from boil off and multiply that by 4. Voila! You’re got your hourly boil off rate.

Some factors that can affect this number are your environment (altitude, humidity, etc…), whether or not you boil with the lid on or off, and the amount of power you have heating your kettle. Running your 3500 watt element at 100 percent will give you a different boil off rate than running that same 3500 watts at 70 percent.

My Process

Start with a simple recipe

I chose to perform my calibration with a simple SMaSH (Single Malt and Single Hop) recipe. You can of course use any recipe you want, but I thought a pale yellow beer would be simplest. For this recipe I went with a recipe that would give me 4.5 gallons into the fermenter. This way I’d know for sure that I would get 3 gallons into a keg. The weights and volumes in the recipe below may seem a little weird and that’s because I brew using metric units. One day I’ll come up with a plugin that will spit out metric and freedom units. More on that decision in a different post.

Recipe Details

Batch Size Boil Time IBU SRM Est. OG Est. FG ABV
4.5 gal 60 min 41.5 3.4 SRM 1.043 1.007 4.73 %


Name Amount %
Pale Malt, 2-Row 8.818 lbs 100


Name Amount Time Use Form Alpha %
Magnum 21 g 60 min Boil Pellet 14.4
Cascade 10.3 g 10 min Boil Pellet 5.5


Name Lab Attenuation Temperature
New World Strong Ale (M42) Mangrove Jack's 77% 32°F - 32°F


Step Temperature Time
Temperature 149°F 60 min

I went into the brew day with pretty much no expectations as far as gravities were concerned. I just wanted to put some water in the kettle with some grain, mash for 60 minutes, boil for 60 minutes with a few hop additions and see what came out the other end.

Pick an arbitrary amount of mash water

With all valves closed (don’t want to fill the chiller just yet) I added an arbitrary 28 liters of water to the kettle. Then I opened the valves to recirculate which fills all of my tubing and my chiller with wort. I noticed that that left me with 27 liters of water in the kettle. This tells me that I have about 1 liter of losses from my chiller.

Milling the grain
My drill battery died so I milled this by hand.
Beginning of the mash
Doughed in and ready to mash.
Measure your pre-boil volume and gravity

Next I added all of my grain and mashed for 60 minutes at 149 degrees fahrenheit. After the mash I pulled out the grain basket and let it drain into the kettle. I measured my pre-boil volume and pre-boil gravity and wrote those down.

Hop additions
Two simple hop additions.
Measure your post-boil volume and gravity

After the 60 minutes boil I recorded my post-boil volume and post-boil gravity. Since you have you pre boil and your post boil volumes you should now have your boil off rate. Write it all down!

Transferring wort to the fermenter
Transferring to the Spike Flex Plus Fermenter
Pitching the yeast
I’ve had this yeast since Home Brew Con 2018. Let’s see how it performs.
Measure the remaining wort in your kettle

Run off into your fermenter and write down how much is left in the bottom of the kettle. With the way my dip tube is positioned in my kettle, my pump isn’t able to get the remaining 2 liters of wort. Try not to guestimate with this measurement. Pour the remaining wort into a measuring cup if you have to. It may be a pain but remember you only have to do this once. (Maybe 2-3 times if you want to average everything out.)

Measure the fermenter losses

After fermentation and after racking into you keg (or bottling), measure how much is left behind in your fermenter. With all of the yeast and trub, you won’t be able to get every last drop out of your fermenter.

Plug it all into your software

Once you have all of this data, you can now go into your equipment profile in your brewing software and input all of the losses you recorded. My tip is to actually do this process a few more times and input the average of your results into your software.


Now that you know exactly what all of your losses are you can have much more predictable and efficient brew day. Your finished beer will be closer to what you expect it to be instead of constantly scratching your head and wondering why you’re 5-10 gravity points from your target. You could even take the data from this process and improve your efficiency by attempting to cut out losses. Maybe you don’t need 10 feet of hose / tubing that costs you 3 liters of wort. Maybe you don’t need to boil at 100 percent power with your 3500 watt element.

Give it a shot!

If you have any questions or comments feel free to ask below or shoot me an email.

The beer was not great by the way…I’ve never been a fan of SMaSH beers. But hey – my equipment profile is bang-on now.


  1. Very cool write-up. Just wanted to get your opinion on your brewtools b40 system. I’m in the market for another all-in-one unit. I’m coming from a Robobrew like yourself (and a single tier system before that). I’m looking at either the brewtools b40 or the unibrau systems. My search only comes up with negative opinions about the brewtools because of all the proprietary parts, etc. Thoughts? Thx in advance.

    1. Hey Nick! Thanks for reading. I love my Brewtools b40 and have been trying to find the time to write a review on the system. Yes, the proprietary parts can be a little frustrating and I do worry sometimes about getting them if they happen to go out of business one day. The parts I see potentially being a problem getting are the three-way valves and their weird 34mm TC fittings. The things I like about it the most is ease of cleaning with the concave bottom and drain in the bottom of the kettle. I never have to move the system…ever. I also love the touch screen controller and all of the potential that it has for hooking up to BrewFather (hopefully they get that up and running soon) and other online techie things.

      The advantage to brau supply, spike and others is that the parts are “here” in the US and Canada (everything Brewtools comes from Norway) and cheaper to ship. I’m pretty sure they also use standard tc fittings. If you want a super simple 240v system and piece of mind then I’d go with the brau supply. If you want something unique that can store recipes in the cloud / talk to the BrewFather app / more automation then go with the Brewtools.

      Hope that helps. I’d love to hear what system you decide on.

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