Free tool

Spirit Blending Calculator

Blending two spirits combines their proof gallons, not their proof. Enter each spirit's volume and proof to get the blended proof, ABV, and how much each spirit contributes. This blending calculator uses the same proof-gallon math as Spirit Sight.

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The formula

blended proof = (PG_a + PG_b) x 100 / (volume_a + volume_b), where PG = volume x proof / 100

A worked example

Blending 100 gallons at 110 proof (110 PG) with 50 gallons at 80 proof (40 PG) yields 150 gallons carrying 150 proof gallons, a blended proof of exactly 100.

Doing this math barrel by barrel? The platform runs the same calculation on every record automatically, reconciled against the books. See it live.

Proof-gallon arithmetic (27 CFR 30.36). This tool uses the same calculation as the Spirit Sight platform. It is general information, not tax or legal advice.

How do you calculate the proof of a blend?
Add the proof gallons of each spirit (volume x proof / 100), then divide total proof gallons x 100 by the total volume. For 60 gal at 120 proof and 40 gal at 90 proof, that is 108 PG over 100 gal, or 108 proof.
Why blend by proof gallons instead of proof?
Proof is a concentration; you cannot average it directly across different volumes. Proof gallons measure actual alcohol, so they add correctly and give the true blended proof.
Can I blend more than two spirits?
The same principle scales: sum every component's proof gallons and total volume, then divide total PG x 100 by total volume. This tool blends two at a time; chain it or use Spirit Sight for multi-component batches.
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