Brewing high gravity can be a daunting task, but I think you'll find that key practices from brewing great low-ABV beer also apply, with a little tweaking, to the high-ABV realm. As such, the tips in this article will apply to all the beer you make.Being "big" is a part of the chemical aspect of a beer. High-ABV beer just acts and needs to be treated differently (not that it necessarily needs different things) than a low-ABV one. Some practices that may not be needed to make a good beer at a lower-ABV are essential to making great high-ABV beers. For the purpose of having some kind of yard-stick, let's call a big beer anything equal to or greater than 8% ABV.Largely, constructing a recipe for high-gravity beers is incredibly similar to the design process of low-gravity ones. However, there are certain things to keep in mind when you go about building your recipe.You do notto get all of your gravity from grains, especially if you don't have your system dialed in. Keep some DME on hand to make adjustments. If we take a look at some Barley Wine recipes from Ray Daniels', the beers from which advanced to the second-round of the National Homebrew Competition, almost 50% use extract so there is no shame in including those guaranteed sugars in your recipe!Second, keep an eye on your OG/IBU (bitterness) ratio. As the OG increases and the beer becomes malty and sweet you will need more bitterness to level out that sweetness. Don't let the high IBUs scare you away; there is a reason that an English Barley Wine has roughly the same amount of IBUs as an American IPA (ranges of 35-70 and 40-70 respectively, per the 2008 BJCP Style Guidelines). Also keep in mind that the higher the gravity of the wort, the less hop utilization there will be which means more hops to reach the same IBUs. Most programs like BeerSmith and BrewToad will do this calculation automatically; I know that BeerSmith uses the numbers proposed by Glenn Tinseth which are also the numbers in John Palmer's. Some brewers don't take this into account at all, but my recommendation is to dial in your system to your palate and stick with it, consistency is key!Finally, not all percentages are created equal. Five pounds of Maris Otter and one pound of Crystal 60L is not the same thing as ten pounds of Maris Otter and two pounds of Crystal 60L, even though they are both about 83% and 17% of the grain bill, respectively. For one, the former has an SRM of about 10 and the latter is about 15 (in a five gallon batch). Plus, two pounds of a malt (let's say Chocolate Malt) are going to result in far more perceptible flavors than one pound, despite being the same percentage of the grain bill. You can use a higher percentage of specialty malts, absolutely, but be aware of your changes and don't always assume that more is better in a big beer. Keep in mind that this is for an "Imperial" version of a recipe, a scaled low-ABV to high-ABV beer in the same amount of liquid. If you are doubling everything in the recipe, including the water, grain percentages work just fine.If you are brewing all-grain, expect your efficiency to drop as your anticipated OG increases. Personally, I can brew a 1.050 beer at 72% efficiency but only get 62% efficiency on a 1.090 beer with the same system. Takes notes and dial in your system, adjust your grain bill as necessary. Don't be afraid of the lower efficiency, consistency is the key here.If you have a really big beer in the works and want to get the most out of your grains, one method of doing so is mashing thin and boiling down. For example, if you have nine gallons of 1.050 wort and boil it down to five gallons, your new gravity would be 1.090. Mashing thin can help you wash more sugars from the wort, and it is a wonderful option if you have the mash tun and kettle to facilitate the volume. I recommend the Boil Off Gravity calculator from Brewer's Friend for this sort of work.If you don't have the kettle to meet a larger volume, a thicker mash (about 1.2qt./lb) can result in a higher efficiency. In a thicker mash, enzymes are more concentrated, increasing conversion rate and making more conversions possible (because of an enzyme's proximity to a substrate). However, there is some evidence (notably from Palmer's) that suggests these thicker mashes can result in sugars that are less fermentable, resulting a sweeter, maltier beer.Finally, anticipate not hitting your pre-boil gravity. It happens. The best thing to do here is to keep some DME on hand so that you can add it to hit the desired OG, or adjust your recipe pre-boil to keep your bitterness ratio.We have all heard the adage that "brewers make wort, yeast makes beer". A big step for any brewer is paying more attention to the yeast, which means selecting the right strain and pitching enough of it.Most yeasts will be able to handle the lower-end ABV of the big beer spectrum, with ABVs in the 8%-10% range, but once you start going higher some yeasts will begin to struggle. As your recipe enters the 10%-12% range, it is important to make sure your yeast will be able to handle that ABV. For example, a classic English ale yeast would be WLP002 English Ale Yeast from White Labs, but once you begin pushing past 10%, you would want to consider WLP007 Dry English Ale Yeast , which boasts a higher alcohol tolerance.The point is to take care when selecting your yeast, and make sure it is the right one for the job. This means considering things other than just the alcohol tolerance, be selective with your yeast. The yeast can be the difference between a good beer and a great beer.A big step towards brewing better beer, any beer, is ensuring that you are pitching enough yeast, and this is just as important for big beers. No matter the yeast you're using, there will be some additional stress on the yeast due to the increased ABV. For an ale, the recommended pitching rate is about .75 million cells per milliliter of wort per degree Plato. Because of the additional stress, the .75 million pitching rate isn't enough to get the most out of your yeast, and to compensate it helps to use a hybrid pitching rate (roughly 1 million cells per milliliter of wort per degree Plato). To make the point, let's take a look at the Proper Yeast Pitching Rates from Mr. Malty. For the example, we will be using the pitching rate for a 5 gallon batch of 1.101 OG beer with .75 million and 1 million cells per milliliter of wort per degree Plato.(0.75 million cells [750,000]) X (18,927 milliliters of wort) X (24 degrees Plato) = 340,686,000,000 cellsSo about 341 billion cells needed for the batch. Now, with 1 million cells per milliliter of wort per degree plato.(1 million cells [1,000,000]) X (18,927 milliliters of wort) X (24 degrees Plato) = 454,248,000,000 cellsSo with the hybrid rate you need roughly 454 billion cells, a difference of 113 billion cells, and those cells are necessary to reduce the stress that the yeast will be under in a higher-ABV beer. You can readfrom Wyeast (listed below) for further reference on this information.If you're using liquid yeast you should already be in the habit of making a starter. Use a yeast calculator (list below) and get a big starter going, proper pitching rates are important for any beer!This is something that some brewers ignore completely and many new homebrewers haven't even heard of, but adding oxygen to the wort is one of the simplest ways to make consistently better beer. How you go about this is up to you, but if you're brewing beer you should be adding oxygen to the wort, simple as that.As the gravity of wort increases, the oxygen solubility decreases, which means that not only does a higher ABV beer need more yeast, but the increased number of yeast cells means more oxygen is needed and the higher gravity means there is less oxygen solubility.In How to Brew John Palmer suggests that he has had better experience with air rather than using pure oxygen, but others are fairly adamant that pure oxygen is the way to go. Regardless, without pure oxygen it will be difficult or impossible to get above 8-9ppm (parts per million), which is short of the ideal 10-12 ppm. For big beers, that ideal range is about 12-13 ppm (BYO Staff). With pure O2, you should be able to reach 12 ppm (in a five gallon batch) in roughly 60 seconds using a diffusion stone.Finally, oxygenate twice. Yeast works with oxygen fairly rapidly, and so it is beneficial to oxygenate again twelve hours after pitching your yeast. This second oxygenation will aid in attenuation and will provide a better environment for your yeast. Don't just take my word for it (or for anything, for that matter), check out these two quotes from White's and Zainasheff's(provided to me by Derek Springer of the excellent blog Five Blades Brewing One of the biggest steps forward in consistently producing great beer is controlling the fermentation temperature, and big beers are no different. There are a few things you can do during fermentation to really help out your yeast, and also to make sure that your fermentation doesn't end a bit early.Obviously, you want to ferment at a temperature that is appropriate for your yeast strain. I won't tell you what to ferment at, especially since this can be dependent on the yeast (as an example, I ferment at the low end of WYeast 1728 Scottish Ale Yeast and at the high end of The Yeast Bay's Vermont Ale Yeast ) but I will tell you that being aware of these temperatures and controlling them is important.Towards the end of fermentation you're going to want to let the temperature free-rise a couple of degrees. The warmer temperatures will help the yeast clean up the beer and will drop the final gravity a bit lower. If you're fermentation is stuck, warming the beer up should help. I typically begin to let the temperature free rise 6F or so a week after pitching. During this time, you can also gently tap the bottom of the fermenter to knock some yeast back into suspension. You don't want to oxygenate your wort here so be gentle, just enough to raise some yeast.Inevitably, you may end up with a stuck fermentation. To fix this, there are a few things you can do. The first I already mentioned, which is to raise the fermentation temperature by a couple degree. The second step you should take is gently knocking the bottom of the fermenter to put yeast back in suspension. You can also gently swirl the fermenter to try and raise some yeast, but be incredibly careful not to oxygenate the beer. You may also want to consider pitching more yeast, since a common cause of a stuck fermentation (especially in high-gravity beers) is pitching too little yeast, or yeast that was not healthy.This article is an incredibly brief introduction to the world of high gravity brewing, and in no way is it meant to serve as a technical resource or a definitive approach to the subject, only to summarize what my experiences with high-ABV beers have been and what my research has shown to be true. If this work interested you, I encourage you to research high gravity brewing further and to develop a foundational understanding of the technical aspects of big beer brewing.Special thanks to the individuals who assisted me in the editing of this article, and all of the people who made this research and work possible. Homebrew Dad [Personal favorite, includes a function for yeast harvesting!]