A member of my High Ester Rum Geeks Facebook group recently asked what LAA means in the context of distilled spirits. For instance, if purchasing rum in bulk, you might be quoted a price per LAA rather than in gallons or liters, as you might expect.

So, what’s the story? What is LAA?

The concise answer is that LAA stands for Liters Absolute Alcohol. But that’s not particularly helpful without further explanation.

All distilled spirits consist of three things:

• Water
• Ethanol
• Congeners (esters, higher alcohols, etc. The flavor!)

Of the three, water and ethanol together constitute the vast majority of any distilled spirit – usually well over 99% of the spirit’s volume.  Water and ethanol are also flavorless; all flavor in a spirit comes from the relatively tiny fraction of congeners, e.g. esters, aldehydes, higher alcohols, etc.… (Read more about them here.)

Thus, if you accounted for all the space (volume) of a 40% ABV spirit, the breakdown would look approximately like this:

• Ethanol: 40%
• Water: ~59.9%
• Congeners: ~0.1%

Now, for certain measurements in the spirits and alcohol business, water is particularly uninteresting. We’d like to deal with the alcohol and congeners, and ignore the water. That’s where LAA comes in.

Let’s look at the two most common real-world examples you might encounter

Congener Measurements (e.g. “ester levels”)

Gas Chromatography (aka “GC analysis”) is a common tool for determining the concentration of various compounds in liquids, including distilled spirits. The primary result from GC analysis is a list of compounds found, and the amount of each per unit volume, i.e. its concentration.

These compounds include a subset of the most commonly encountered congeners, of which there are typically hundreds in a distilled spirit. Here’s an example of a GC analysis of a well-known rum, which I shall not name.

Warning: Geekiness ahead!

In the GC data, note that the concentration of each compound is given in “g/hl AP”. That’s shorthand for “grams per hectoliter of alcohol pure”.  (In this report, “alcohol pure” is equivalent to “absolute alcohol”.)

Let’s restate this: The concentration of compounds is given per unit of alcohol (ethanol) in the liquid, not the total volume of the liquid. The liquid’s water component, however much that is, doesn’t matter in these measurements.

This is critical to understanding LAA. For the purpose of measuring the concentration of compounds, the water portion is irrelevant.

Thus, if you took a sample of Hampden Estate DOK rum at 85% ABV, and diluted a portion to 40% ABV, then ran a GC analysis on the two samples (85%, 40%), the GC data would report the same concentration of compounds. The amount of water dilution is immaterial.

As an interesting aside, the ester level of Jamaican rum is traditionally given in the units described above, i.e. grams per hectoliter of absolute alcohol. Thus, a Jamaican rum with a “550 ester level” means there are 550 grams of esters in 100 liters of ethanol. But…. a word about those esters….

It should also be known and understood that the traditional Jamaican ester level measurement only refers to a single ester: Ethyl Acetate.

That particular ester is the most common ester found in distilled spirits, and has a specific fruity note. However, it’s the dozens of other esters and compounds, in far less concentration, that are the most interesting when it comes to flavor profile. In short, Jamaican ester levels are a very one-dimensional perspective. We can do much better, but that’s a topic for another story.

Pricing / Taxation

The second common way you might encounter LAA is when purchasing distilled spirits or paying taxes on them. Compared to the ethanol a distillery makes, water is incredibly inexpensive, and it can always be added later at a relatively low cost. It’s easily factored out of the equation.

For that reasons, the production capacity of distilleries and alcohol plants is given in LAA, rather than the volume of what goes in ISO tanks for shipping, i.e. water + ethanol.

Likewise, if you were purchase a distilled spirit from a distillery, the price would likely be given per LAA.  Odds are, they’d ship it to you at a fairly high ABV, after which you could dilute it to whatever you desire. Or not.

It’s the same story for excise taxation. Governments charge on the ethanol content of a bottle, not the total volume. Thus, the excise tax due on a bottle of 120 proof cask-strength bourbon will be higher than the same bourbon at 80 proof — there’s more ethanol in the bottle.

Proof Gallons

Related to LAA is another commonly used U.S. term: Proof gallon. The TTB describes a proof gallon like this:

A proof gallon is one liquid gallon of spirits that is 50% alcohol at 60 degrees F.

A proof gallon is 50% ethanol and 50% water. Thus, a proof gallon is another way of representing the amount of ethanol present.

The amount of ethanol in a proof gallon can be converted to LAA by multiplying the proof gallon quantity by 1.8927.

Absolute Alcohols is Rare (Azeotrope)

As a final geeky note tangentially related to the above, 100% pure ethanol is difficult to come by, and requires special distillation equipment. This has to do with a chemistry term known as azeotropes. Without trying to explain the exact chemistry, using traditional fractional distillation like you’ll find at most distilleries, it’s impossible to get ethanol at a concentration above 97.2 percent ABV (or 95.63 percent ABW). The still is simply unable to remove that last ~4 percent of water.

If that 95% figure sounds familiar, it’s because many column distilled spirits come close to that value. Neutral spirits are distilled to around 96% ABV or higher. They’re called neutral spirits because nearly all of the flavor-giving compounds have been stripped out by the distillation. Many vodkas and gins start out as neutral spirits.

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So, that’s today’s boozy science lesson! While I make no claim that what I’ve said meets any legal definition, hopefully it’s added to your understanding of this complex, misunderstood corner of the distilled spirits industry.