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Barrel Aging Calculator

Estimate barrel aging volume loss from angel's share and calculate aged spirit yield. Evaporation rates by climate and barrel size.

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Inputs that matter
Barrel Size, Ambient Temperature, Spirit Type, Age (years)
Output to expect
Barrel Aging Estimator
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
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Reference & details

How it works

Angel's Share Rate

Evaporation rate depends on climate, barrel size, and warehouse conditions. Smaller barrels have higher surface-to-volume ratio and faster loss.

Annual loss = 2–4% (Scotland/humid) | 4–10% (Kentucky/dry)

Compound Volume Loss

Loss compounds annually on remaining volume. 10% annual loss for 4 years: 0.9^4 = 66% remaining (34% total loss).

Remaining = Initial × (1 − Rate)^Years

Proof Increase

In dry warehouses (Kentucky), proof increases 1–3 degrees per year. Humid climates (Scotland) may decrease proof as alcohol evaporates preferentially.

Proof rises as water evaporates faster than ethanol (in dry climates)

Updated: July 2026

Example Scenarios

Initial 53 gal, 5% annual loss: 53 × 0.95^4 = 43.3 gal remaining. Proof rises from 125 to ~130 entry proof.

Higher surface ratio: 8% annual loss. 15 gal × 0.92^2 = 12.7 gal. Faster extraction, faster evaporation.

2% annual loss in humid dunnage warehouse: 200L × 0.98^12 = 157L. Proof may drop 2–4 degrees over 12 years.

FAQ

Volume lost to evaporation during barrel aging — typically 2–10% per year depending on climate, barrel size, and storage conditions. Named for the share lost to the heavens.

Water and ethanol evaporate at different rates depending on humidity. Dry climates: water evaporates faster, proof increases. Humid climates: alcohol evaporates faster, proof decreases.

Yes. Higher wood surface-to-volume ratio extracts flavor faster but also increases angel's share. 15-gal barrel may achieve 4-year flavor in 12–18 months.

At 3% annual loss: 0.97^10 = 74% remaining. At 5%: 0.95^10 = 60% remaining. Climate and barrel size significantly affect actual loss.

Humidity-controlled warehouses, larger barrels, and proper barrel storage (not over-heated rickhouses) reduce loss. Some loss is essential to concentration and maturation.

About Barrel Aging Calculator

Barrel aging loses volume to evaporation (angel's share) and absorption into wood. Enter initial fill volume, barrel size, aging duration, and climate to estimate remaining volume, proof change, and final bottle yield.