dram · how the valuation works · 2026

How dram values a cask

Real comparables, a per-cask growth curve, and the angel's share — the actual formulas behind every figure, projection, and chart in the app.

WESTPOINT

01 / the model

Every cask gets its own curve

ln(price) = a + b · age

value(age) = e^{a + b · age}
a bottle compounds at ≈ (e^b − 1) per year

Built on real comparable salesa best-fit price line through the cask's own comparable retail & auction sales — so every cask is valued on its own evidence, never lumped into a market average.

a, b — the cask's own linea sets the starting level, b the yearly growth rate — together they draw one smooth price-vs-age curve for that cask.

R², σ — how confident the fit isboth show how tightly the comparable sales cluster around the line, and both are shown on the chart — so you always see how solid a valuation is.

Today and the trajectory"today" is the curve read at the cask's current age; Y1 / Y3 / Y5 / Y10 read it further along. One line — a figure for now and the path ahead.

a best-fit price curve, built from each cask's own comparable sales

02 / the home charts

The dashboard charts — three reads of the market

All three read the public auction market at one consistent age — the value of a 20-year-old bottle — so every comparison is like-for-like. price@age = e^{a + b · age}

Market index · whole market · over time

Purpose: is cask whisky rising or cooling, and when? Time entries, exits and expectations against the whole secondary market.

Example — the run-up to the 2022 peak, then the cooling through 2024, on one indexed line (base year = 100).

Distillery trend · one name · over time

Purpose: has a single distillery beaten or lagged the market? Spot the names with real momentum before pricing a cask.

Example — Springbank's steep climb set against a steadier Speyside name, each rebased to 100.

Distillery benchmark · compare names · snapshot

Purpose: which distilleries command the most per bottle right now? Rank a name and frame what a cask of it could fetch.

Example — a 20-yr-old Macallan towering over a mid-tier Speyside, in actual £ (every bar on an equal sample).

built from the public auction market — index, distillery trend & benchmark

03 / the angel's share

A cask is a leaking clock — bottles fade every year

bottles(age) = N₀ · (1 − r)^age · N₀ = RLA ÷ (0.7 × ABV)

fill

250 L bulk · 63.5%
≈357 bottles

✓ certificate

+10 yrs

~205 L · ~58%
≈295 bottles

~2%/yr est.

+20 yrs

~168 L · ~53%
≈242 bottles

~2%/yr est.

re-gauge

140 L bulk · 49%
≈200 bottles

✓ certificate

The angel's share~2% of the liquid evaporates through the oak every year. It can't be calculated back — only re-measured, with a re-gauge.

Alcohol leaves faster than waterso ABV drifts down toward the 40% legal floor — below it, the spirit can no longer be sold as Scotch whisky.

Fewer litres → fewer bottles → less valuethis illustrative cask sheds ~157 bottles over its life. The fill OLA and the re-gauge RLA certificates capture it.

illustrative · how a cask's bottle count drains with the angel's share

04 / outliers

Some comps sit off the curve — and they're real

outlier = a comp beyond ±2σ of the cask's own fitted curve — no global threshold. Most comps hug the curve; only a small share don't.

After cleaning, the outliers that remain aren't noise — they're genuine market facts, in three buckets:

Vintage rarity premium · high side

old, scarce distillations, far above any age curve — e.g. Clynelish 1965 Signatory #666 · £10,000 @ 28yo

Trophy & limited editions · high side

single-cask & special releases with a collector premium — e.g. Caol Ila Manager's Dram 1990 · £2,425 @ 15yo

Old sales at old prices · low side

a sale logged years ago reads low against today's market — e.g. Macallan Edition No.1 · £175 in 2015 → £1,050 in 2026

Bad data screened outwhole-cask lots, miswritten vintages and wrong ages are filtered before they ever count

Easy to spotreal outliers sit far off the cask's own curve, so they stand out at a glance — one untick removes them

You stay in controluntick any comparable and the valuation recalculates instantly on the rest

Never auto-deletedgenuine outliers are real market facts — you decide what counts

outliers are flagged against each cask's own curve — surfaced for review, never removed automatically

05 / worked example

From certificate to cask value — a worked example

The cask · illustrative

Cask typeHogshead

Filled1996

Age today30 yrs — derived from fill date

OLA (alcohol at fill)not recorded — like most casks

Last re-gauge2025

RLA (alcohol remaining)75.0 L

Strength at re-gauge52.0%

Bottle yield206 — computed, never typed

Acquired cost£300,000

The calculation

175.0 ÷ (0.7 × 52.0%) = 206.0 → 206 bottles the re-gauge certificate turned into a bottle count
2ln(price) = 4.76 + 0.113 × age — fitted on its own comps (r² ≈ 0.4) the cask's own price curve — valued on its own sales, never a market average
3e^(4.76 + 0.113 × 30) ≈ £3,500 per bottle at today's age the curve grows ≈ +12%/yr — read off wherever the cask's age clock stands
4206 × 0.987^1 ≈ 203 bottles left today with only one measurement, this cask can't gauge its own loss rate yet — so the standard rate applies (1.3%/yr, measured from real re-gauge histories). Add its fill OLA or a second gauge and it switches to its own measured rate automatically
5203 × £3,500 = £710,500 cask value today acquired at £300,000 → +137% · the saved valuation freezes the count at 206 (£721,000); the display shrinks it for the angel's share

£710,500

203 btl × £3,500

today · age 30

£1,171,920

190 btl × £6,168

+5 yrs · age 35

£1,934,860

178 btl × £10,870

+10 yrs · age 40

£3,199,386

167 btl × £19,158

+15 yrs · age 45

£5,266,872

156 btl × £33,762

+20 yrs · age 50

click a year — steps 3–5 above re-run the same calculation at that age

illustrative figures · the cask's own price curve × bottles after the angel's share