Comparing cask prices when one says OLA and another says RLA

Stock lists mix their units more often than you'd think. One row is priced per OLA, the next per RLA, and some volumes come with a tilde in front. Two casks can look cheap and dear on paper and turn out to be the other way round.

The terms

Bulk litres

The volume of liquid in the cask.

ABV

The share of that liquid that is pure alcohol.

LPA

Litres of pure alcohol, which is bulk litres × ABV.

OLA

Original litres of alcohol: the LPA when the cask was filled.

RLA

Regauged litres of alcohol: the LPA measured at the most recent regauge.

Say a cask was filled with 250 bulk litres at 63.5%. That's 250 × 0.635 = 158.75 OLA. Years later, a regauge finds 210 bulk litres at 57.2%, which is 210 × 0.572 = 120.12 RLA. OLA tells you what went in. RLA tells you what's there now.

Putting two prices on the same footing

A price per OLA and a price per RLA are in different units, so you can't compare them directly. To compare casks fairly, divide each cask's total price by its RLA. That gives you a price per litre of alcohol that's actually in the cask today.

For the same total price, the price per RLA is always the higher figure once any alcohol has been lost. If a cask has lost a fifth of its alcohol since filling, its price per RLA is a quarter higher than its price per OLA. Try it with your own figures.

So a lower number next to OLA isn't automatically cheaper. Read the unit, the age, the regauge date and the total price together.

When to ask for a regauge

A regauge is the warehouse measuring the cask's current bulk litres and strength. It usually takes about two weeks. Ask for one, or price the uncertainty in, when any of these apply.

• The cask is older and priced only on OLA.
• There's no regauge date, or it's an old one.
• The ABV isn't given.
• The figures don't add up, because OLA × the price per OLA doesn't match the cask price.

Losses to evaporation vary with the cask, the warehouse and the years, so no rule of thumb tells you what's left in a particular cask. Only a measurement does.

Strength matters too. Scotch whisky must be bottled at 40% ABV or more, so a cask with little strength to spare above 40% needs watching on a long hold. Many warehouses also won't draw samples from casks under three years old, so for young stock the regauge report and the cask record are often what you have to go on.