Spirit Aging Evaporation Loss Calculator

ANA›Life Services Authority›National Calculator Authority›Spirit Aging Evaporation Loss Calculator

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Spirit Aging Evaporation Loss Calculator

Estimate the volume and alcohol lost during barrel aging of spirits — commonly known as the Angel's Share. Accounts for barrel size, climate, aging duration, and initial fill parameters.

Initial Fill Volume (litres)

Total liquid volume placed in barrel

Initial ABV (%)

Alcohol by volume at fill (40–94.8%)

Barrel Size (litres)

Standard sizes: 53 gal (200 L), 30 L, 500 L

Aging Duration (years)

Minimum 0.25 years (3 months)

Climate Type

Cool / Scottish (1.5–2% / year) Temperate / Irish (2–3% / year) Continental / American (3–5% / year) Tropical / Caribbean (5–8% / year)

Climate drives annual evaporation rate

Warehouse Position

Lower Floor (cooler, slower) Middle Floor (average) Upper Floor (hotter, faster)

Upper floors lose more due to heat cycling

Barrel Char / Toast Level

New Oak – Heavy Char (#4) New Oak – Medium Char (#2–3) Used / Refill Barrel Ex-Sherry / Wine Cask

New charred oak increases evaporation slightly

Spirit Value ($/litre of pure alcohol)

Optional: for financial loss estimate

Calculate Angel's Share

### Evaporation Loss Results

function spiCalc() { const errEl = document.getElementById('spi-error'); const resEl = document.getElementById('spi-result'); errEl.style.display = 'none'; resEl.style.display = 'none';

// --- Inputs --- const V0 = parseFloat(document.getElementById('spi-initial-volume').value); const abv0 = parseFloat(document.getElementById('spi-abv').value); const barrel = parseFloat(document.getElementById('spi-barrel-size').value); const years = parseFloat(document.getElementById('spi-years').value); const climate = document.getElementById('spi-climate').value; const wh = document.getElementById('spi-warehouse').value; const charLvl = document.getElementById('spi-char').value; const price = parseFloat(document.getElementById('spi-spirit-price').value) || 0;

// --- Validation --- const errors = []; if (isNaN(V0) || V0 0."); if (isNaN(abv0) || abv0 94.8) errors.push("ABV must be between 40% and 94.8%."); if (isNaN(barrel) || barrel 0."); if (!isNaN(V0) && !isNaN(barrel) && V0 > barrel * 1.05) errors.push("Fill volume cannot exceed barrel capacity (allow 5% headspace)."); if (isNaN(years) || years 50) errors.push("Aging duration cannot exceed 50 years.");

if (errors.length) { errEl.innerHTML = errors.map(e => '⚠ ' + e + '

').join(''); errEl.style.display = 'block'; return; }

// --------------------------------------------------------------- // BASE ANNUAL EVAPORATION RATE (% of remaining volume per year) // Source: Distilled Spirits Council; Piggott et al. (1989); // Conner & Paterson "A Practical Guide to Whisky Flavour" // --------------------------------------------------------------- const climateRates = { cool: 0.020, // ~2.0% / yr (Scotland avg) temperate: 0.025, // ~2.5% / yr (Ireland, mild US) continental: 0.040, // ~4.0% / yr (Kentucky avg) tropical: 0.065 // ~6.5% / yr (Caribbean avg) };

// Warehouse position modifier const whMod = { lower: -0.003, middle: 0.000, upper: 0.005 };

// Barrel char / type modifier // New charred oak has more micro-pores → slightly higher loss const charMod = { new_heavy: 0.004, new_medium: 0.002, used: 0.000, ex_sherry: -0.001 };

// Barrel size modifier: smaller barrels have higher surface-area-to-volume ratio // Reference: Neto et al. (2019) – evaporation scales with SA/V // SA/V for a cylinder ≈ 2(r+h)/(r·h) — approximate with empirical factor // Normalised to 200 L barrel; factor = (200/barrel)^0.25 const sizeFactor = Math.pow(200 / barrel, 0.25);

const annualRate = (climateRates[climate] + whMod[wh] + charMod[charLvl]) * sizeFactor;

// --------------------------------------------------------------- // COMPOUND EVAPORATION MODEL // Each year the loss is applied to the remaining volume: // V(t) = V0 × (1 − r)^t // where r = annual evaporation rate (fraction) // --------------------------------------------------------------- const Vfinal = V0 * Math.pow(1 - annualRate, years); const Vlost = V0 - Vfinal; const pctLost = (Vlost / V0) * 100;

// --------------------------------------------------------------- // ALCOHOL CONTENT CHANGE // In cool/temperate climates water evaporates faster → ABV rises // In hot/tropical climates alcohol evaporates faster → ABV falls // Empirical ABV drift rates (% ABV per year): // cool/temperate: +0.1 to +0.3 %/yr // continental: +0.05 to +0.15 %/yr (mixed) // tropical: −0.2 to −0.5 %/yr // Source: Conner & Paterson; Kew et al. (2020) // --------------------------------------------------------------- const abvDrift = { cool: +0.20, temperate: +0.15, continental: +0.08, tropical: -0.30 }; const abvFinal = Math.min(94.8, Math.max(40, abv0 + abvDrift[climate] * years));

// Pure alcohol (litres of absolute alcohol, LAA) const laa0 = V0 * (abv0 / 100); const laaFinal= Vfinal * (abvFinal / 100); const laaLost = laa0 - laaFinal; const pctLaaLost = (laaLost / laa0) * 100;

// Financial loss const financialLoss = laaLost * price;

// --------------------------------------------------------------- // YEAR-BY-YEAR BREAKDOWN (every year or every 0.25 yr if ' + tRound.toFixed(2) + '' + Vt.toFixed(2) + '' + abvT.toFixed(1) + '' + laaT.toFixed(2) + '' + cumLoss + '%'; if (t >= years) break; }

// --------------------------------------------------------------- // OUTPUT // --------------------------------------------------------------- const rows = [ ['Initial Volume', V0.toFixed(2) + ' L'], ['Final Volume (estimated)', Vfinal.toFixed(2) + ' L'], ['Total Volume Lost', Vlost.toFixed(2) + ' L (' + pctLost.toFixed(2) + '%)'], ['Initial ABV', abv0.toFixed(1) + '%'], ['Estimated Final ABV', abvFinal.toFixed(1) + '%'], ['Initial Pure Alcohol (LAA)', laa0.toFixed(2) + ' L'], ['Final Pure Alcohol (LAA)', laaFinal.toFixed(2) + ' L'], ['Pure Alcohol Lost', laaLost.toFixed(2) + ' L (' + pctLaaLost.toFixed(2) + '%)'], ['Effective Annual Loss Rate', (annualRate * 100).toFixed(2) + '% / year'], ['Aging Duration', years + ' years'], price > 0 ? ['Estimated Financial Loss', '$' + financialLoss.toFixed(2)] : null ].filter(Boolean);

document.getElementById('spi-table').innerHTML = rows.map(r => '' + r[0] + '' + r[1] + '').join('');

document.getElementById('spi-breakdown').innerHTML = '#### Year-by-Year Breakdown ' + '' + 'YearVolume (L)ABV (%)' + 'Pure Alcohol (L)Cumulative Loss' + '' + breakdownRows + '';

resEl.style.display = 'block'; }

#### Formulas Used

Compound Evaporation Model:

V(t) = V₀ × (1 − r)ᵗ

Effective Annual Rate:

r = (r_climate + r_warehouse + r_char) × (200 / barrel_size)^0.25

The barrel-size correction reflects the higher surface-area-to-volume ratio of smaller casks.

Pure Alcohol Lost (LAA):

LAA_lost = V₀ × (ABV₀/100) − V(t) × (ABV_final/100)

ABV Drift: Linear approximation based on climate-driven differential evaporation of water vs. ethanol.

#### Assumptions & References

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