How Much Whiskey Evaporates During Aging: Angel Share

In our experience, everyone in a distillery is familiar with what “Angel’s Share” is but not all who are familiar with whiskey know what it is. When whiskey is still aging in the wood, a tiny amount will evaporate entirely. For each year it’s about 1-2% of the whiskey in the barrel. A lot of folks in the industry like to think of it as a token sacrifice to the heavens above. You can’t fight it either, so may as well give the angels their fair share.

Angel’s Share: Why It Happens

Age Is A Factor

Depending on how old your whiskey is, you’ll see a difference in how fast it can evaporate. Younger whiskey’s are known to evaporate a bit faster than older ones. That’s why we much prefer to use older ones. Believe it or not for a newer whiskey, the evaporation can be up to 4% per year. As it continues to age it will slow down to 1-2%.

As people have asked before, it is real and the whiskey even in the barrel will never stop evaporating. So a 20-year old whiskey could lose as much as 50% of its original volume in a 30-year period.

The Size Of Your Wood (Barrel)

Another factor that can help your evaporation slow down is how big the barrel you use to age your whiskey is. Smaller barrels will generally evaporate more since there is more contact with the whiskey. In our experience aging with smaller barrels, the ones that are 20 liters and less evaporate much faster but they can help age the whiskey faster as well.

The Climate and General Temperature For Storing

There’s a good reason that many whiskey warehouses, distilleries, and other aging places put up shop in Kentucky. In the summer the warehouse temperatures on all floors can get anywhere from 90°F – 120°F, while bottom floors may only be 50°F-70°F. It’s a big range and affects how much whiskey evaporates and how fast it can age. Since Kentucky is humid, typically the water will leave the barrel before the alcohol does – making it a bit stronger in the process.

So when you’re storing – pick a bigger barrel and store it in a place where the temperature doesn’t fluctuate so much (like a cellar, basement, or a warehouse is good). You might also like it to be a little humid (we prefer our spirits to be stronger after the aging).

The Way To Store Your Barrel

Lastly, we need to talk about how to store your barrel (it can make a difference). Most warehouses will have racks, pallets, or anything else where the barrels can be stored on in rows. It’s a good idea since airflow can promote evaporation (which is not always bad). Having a bit of evaporation will make the whiskey stronger but if you’re wanting to avoid it – having less barrels will help avoid it.

Angel’s share can add up to a significant amount over the years but its something to accept. For example, a barrel of whiskey aged for 10 years could lose up to 20 liters of whiskey to evaporation, but what you can’t measure is how much better your whiskey tastes because of it. It’s something that whiskey agers across the board have come to expect and plan for.

Although whiskey evaporates during the aging process, this isn’t necessarily a bad thing. The angel’s share is actually an important part of the whiskey-making process, as it helps to create the flavor and aroma of the finished product (also helps make it stronger). So the next time you’re sipping on a glass of whiskey, remember that a portion of the whiskey has been lost to evaporation, which helps to make it so delicious.

FAQ About How Much Whiskey Is Lost

How much bourbon is lost during aging?

A good aged whiskey is likely to lose approximately 20-40% percent of the original volume by the time it’s bottled 10+ years later. You an prevent this or minimize it by using a bigger barrel to age your bourbon.

How much bourbon evaporates per year?

It depends on a few conditions but on the low end 1-2% per year and on the high end, 3-4% per year. This is from angel’s share, the natural evaporation of the whiskey during aging. It’s typical for a whiskey to lose around ~30% of it’s original volume by the time it’s ready to be bottled.

What is the 2% loss of whiskey per year due to evaporation from the barrel often referred to as?

Angel Share, which is a loss from 2-5% actually and while it can be minimized, it won’t ever be prevented.

2 thoughts on “How Much Whiskey Evaporates During Aging: Angel Share”

  1. As I understand it, a standard whiskey barrel holds about 200 liters of whiskey. You stated:

    It is estimated that up to 1-2% of the whiskey in the barrel is lost to evaporation each year. This can add up to a significant amount over the course of several years. For example, a barrel of whiskey aged for 10 years could lose up to 200 liters of whiskey to evaporation.

    Help me understand how that last sentence is possible….

    • Hey David, good question and losing all the whiskey in your barrel to evaporation would be ridiculous, I agree.

      I think your math is a bit off and you’re thinking about the evaporation rate the wrong way. After 10 years with 200 liters, you would only lose 20 liters since 200 x 0.01 = 2 (1% = 0.01 and not 0.1) and 2×10 = 20.

      However, you wouldn’t even lose the full 20 liters because the rate would change as you lose whiskey in the barrel. Lets say you fill it up with 200 liters and don’t take any out or put any more in. The first year you would lose 2 liters since 200 * 0.01 = 2 liters but the year after it would be (200-2) 198 liters * 0.01 = 1.98 liters. So the amount of whiskey you lose over time shrinks as the amount of whiskey in the barrel shrinks.

      Hope that answers your questions


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