From Barrel-to-Bottle: Breaking Down Whisk(e)y Proof


wooden barrel in a stone wall room with branded titled barrel-to-bottle


There are a lot of ways to classify, and market, the proof of a whiskey, including cask strength, barrel proof and bottled-in-bond. These label terms might make complete sense to whisk(e)y aficionados but can cause confusion for less experienced customers. To make sure you’re able to answer your customers’ questions quickly and confidently, we’ve created a quick refresher breaking down the different proofs a whisk(e)y, all the way from the barrel to the bottle.

wooden sign with proofing gauge graphic on a stone wall

Barrel Entry Proof

No Higher than 125 Proof

This is the proof that unaged spirit enters the barrel.

Cask Strength and Barrel Proof

105-135 Proof

Whiskies labeled cask strength or barrel proof are bottled at the exact proof that the whisk(e)y is at in the barrel. No water is added, but the whisk(e)y is filtered before bottling.


100 Proof

The Bottled-in-Bond Act of 1897 states that all American whiskey labeled bottled-in-bond must be bottled at exactly 100 proof.

Prohibition Strength

90-100 Proof

Before Prohibition, bottles did not have to bear a proof statement, but the norm for bottled whiskey until 1920 was 100-90 proof.

Post-Prohibition Strength

84-90 Proof

After Prohibition was repealed in 1933, most U.S. produced whiskeys were bottled around 90 proof.

Minimum Bottle Proof

80 Proof

In both the U.S. and Scotland, 80 is the minimum proof for any bottled whiskey. The lower proof was a result of three things: increasing U.S. excise duties, social concerns about alcohol consumption and competition with lower proof clear spirits such as vodka and gin.

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