The size of a wine bottle tells you more than how many glasses you’ll be able to pour from it.
“Bottle format undoubtedly has an effect on a wine’s ability to age,” says Erik Elliott, estate director for Heitz Cellar. “It is all a result of oxygen exchange relative to the amount of wine in [the] bottle.”
A magnum has about the same ullage, or space between the top of the liquid and the bottom of the cork, as a standard 750ml bottle. However, it has twice the volume of wine. The ratio of wine to oxygen is significantly impacted and, by extension, so is the aging potential of the wine and the speed at which it occurs.
Consultant Ted Glennon of Asilomar Fine Wine, points out that when considering a 375ml, a 750ml, or a magnum, “each of these formats are sealed with essentially the same amount of available atmosphere at bottling as a 750ml,” and “as such they react with the wine at a different rate.”
The volume of wine also affects the amount of time it takes the liquid to heat up and cool down.
“A normal wine cellar works on a three-degree differential, so it cycles from 54–57˚F,” says Scot “Zippy” Ziskind, president of Zipco Wine Cellar Services and COO of My Cellar Pennsauken Wine Storage. “A smaller bottle will feel that change more quickly, whereas a larger one, like a six-liter, will feel it less. The larger the liquid mass, the better it’ll hold temperature, and the slower it will age.”
Over the course of his decades in the industry, Ziskind has seen how splits age faster than 750s, how jeroboams age more slowly than magnums, and so on.
Elliott has as well.
“The best example I ever experienced firsthand was 2003 Château Lafite Rothschild in half-bottle versus magnum,” he says. “It was as clear as day that the half-bottle had matured exponentially faster. The older the bottles get; the more important format becomes.”
But that doesn’t mean that one is better than the other.
“It all depends on when you plan on pulling the cork and enjoying the bottle with friends, and what you find most enjoyable in wines with age,” says Elliott.