The short answer is that it may take you 1 to 3 years to realize the cost savings if you brew twice a month. This factors in both the cost savings on ingredients and also efficiency gains. A key reason this takes so long pay off is that the cost of the mill is very high compared to grain savings per batch.

Why buy a grain mill in the first place?

The most common reason homebrewers buy a mill is to increase efficiency by reducing the crush size of the grain, coinciding with the rise of brew-in-a-bag (BIAB) brewing. With the BIAB technique, the usual crush size that is done at the local homebrew shop or online is not small enough to maximize efficiency.

Another common reason is that it allows brewers to buy unmilled grain in bulk for longer storage. Saving money at the homebrew scale is more easily achieved when you buy in bulk. The common understanding is that unmilled grain both lasts longer and is cheaper than milled grain, so in order to take advantage of those savings a mill must be used.

How much do grain mills cost?

Grain mills range from ~$125 for the cheapest double roller mill to the $1000+ range (yes this is marketed to homebrewers). With such a large range, the main factors you pay for are throughput in lbs/min, capacity in hopper volume and quality/flexibility of the mill. Most homebrewers own mills on the lower end, with the majoring having double mill rollers that can be powered by a power drill. For the sake of calculating the cost savings, we’ll stick with the cheapest $125 option.

How long does it take to break even?

Assuming the grain mill costs $125, how many batches it would take to pay that off? For the sake of example, let’s use Pale Malt. Looking at MoreBeer, they sell Viking Pale Malt in 10lb bags for $15.99 each for unmilled and $18.29 milled. Finding the best price of pale malt is an interesting topic and likely one I will dive into in another article. For now, it’s important to know the price per pound of the grain you’re buying including shipping costs. In this example, the price per pound is $1.60 for unmilled and $1.83 for milled.

Note: When I calculated this price a year ago, the price per pound was much lower, $1.01 for unmilled and $1.20 for milled. It seems that grain shortages and inflation have made a big impact. A grain mill is actually more affordable now because you can save more per batch.

Let’s assume that the recipe calls for 10lbs of grain. This means you save $2.30 per batch, therefore it would take 54.35 batches to pay for the $125 mill. If you generally brew twice a month, it would take you roughly 2.25 years to pay off the mill. That’s almost $1000 worth of grain… If you brew less frequently (1x per month), you’re looking at 4.5 years to pay this off.

If this was the whole story then a mill doesn’t seem worth it if you don’t brew frequently. We’d all like to look into a crystal ball and know we will brew 55 batches, but that is pretty serious dedication. Thankfully there is another factor at play here.

Factoring in efficiency gains

For many BIAB brewers, they will see an efficiency gain when milling their own grain. Anecdotally, it’s possible to see large changes up to +10%. Let’s use an extreme example where efficiency went from 67% to 77%. In this scenario, you can use less grain in their recipe to hit the same numbers. Where before you would use 10lbs, you now only need 8.7lbs.

With this in mind, we can calculate our costs per batch for both scenarios. In the pre-milled scenario, you keep buying milled grain at $18.29 a batch. In the mill-it-yourself scenario, you pay $125 up front and buy unmilled grain at $13.91. Thinking back to algebra, we can plot these equations as lines on a graph, mx+b. 18.29x + 0 for pre-milled and 13.91x + 125 for mill-it-yourself. Where they intersect is where it becomes more efficient to go with scenario 2.

Now we only need to brew 29 batches to get our money back. That’s about 1.25 years at 2 brews a month. That’s a $530 investment required to break even. When we take efficiency boosts into account, it becomes a double boost to our savings: buying cheaper grain and using less of it.

Estimating a real grain bill

The other factor we skimmed over is grain costs. We went with the cheapest grain (Pale Malt) in the example but specialty malts cost more. If we use Floor Malted Bohemian Pilsner, the price goes up to $2.25 per pound unmilled and $2.45 milled. That gives us an intersect at 25 batches or $621 invested. It takes fewer batches to get our money back but overall requires a higher dollar investment. In reality, our average cost of our whole grain bill will be somewhere in the middle, with mostly low cost base malts but some specialty or higher cost base malts added in.

If you brew higher OG beers, that will also decrease the number of batches you need. If we keep the average cost from above and assume a 15lb grain bill (1.071 OG), then it changes the intersect to 17 recipes.

Considering the price of the mill

One last quantifiable factor is the cost of the mill. As stated above, there are different tiers of mills ranging from $120 to $1000+. Based on the calculations above, this changes the calculation significantly. Assuming $4 in savings per recipe, that gives a pretty wide range depending on the price of the mill:

Mighty Mill 2 Roller - $125 - 31 brews to break even

Monster Mill 3 Roller - $284 - 71 brews to break even

This is a pretty significant difference and a great example where doing your homework and jumping on a sale could save a lot of money.

If you’re assuming the crush is the same in granting higher efficiency and also assuming the mill will last a lifetime, you should just go with the cheapest mill you can find. There are plenty of reviews out there to look at, so please do your own research but if cost savings is your main driving factor then cheaper is better.

Other factors to consider

Some other things to consider are freshness and ease of use. If you are buying recipes in bulk, you may have grain sitting around for several months until it’s brew day arrives. It’s debatable whether this actually is perceptible in a finished beer and brulosophy has a great experiment on this. Personally I’m not too worried about milled grain laying around for months as long as it’s in a cool, sealed environment.

Ease of use should be pretty straight forward with any mill but you may want to check that it has some basic quality of life features. For example make sure you can run the mill with a power drill. That seems to be the best way to run a mill without adding additional costs. If you don’t have a drill then a hand crank should come with the mill, but if you aren’t interested in manually turning the mill then that may factor into your decision.

Conclusion

It takes 30-50 brews to break even on an inexpensive grain mill.

To summarize, if you don’t get any efficiency boost by using finer milled grains then it’s not really worth it unless you plan on brewing for 2+ years. This seems like a chicken and the egg problem so if you want to test this out without making the investment, then have your LHBS double crush your batch. That should help you test a finer crush without using your own mill.

Cheers!