Wine Barrels: Oak Types, Sizes, Toast and How They're Made

Wine barrels are oak casks that winemakers use to ferment or age wine. A barrel does two things a steel tank can’t: the wood adds flavors such as vanilla, spice and toast, and its pores let tiny amounts of air reach the wine, which softens it over months or years. The classic size is the 225-liter barrique. This guide covers French vs American oak, barrel sizes, toast levels, new vs neutral oak and how a cooper builds a barrel.

What oak barrels do to wine

The Lodi Winegrape Commission, the body for California’s Lodi wine region, sums up a barrel’s job in three parts:

• Slow oxygen. Porous wood lets in a little air over months or years, along with slight evaporation that concentrates the wine. Wine Folly says this slow oxygen makes wine taste smoother and less astringent.
• Flavor. Oak gives aromas that resemble vanilla, which can make a wine seem “sweeter” even when it is dry.
• Toast. Staves are bent over an open fire, and the charred inside adds toasty or smoky notes.

Wine Folly lists the main oak compounds and the aromas they bring:

Compound	Aroma (Wine Folly)
Vanillin	Vanilla
Syringaldehyde	Vanilla-like
Eugenol	Spice, clove and smoke
Furfural	Dried fruit, burned almond, burnt sugar
Guaiacol	Burnt notes
Oak lactone	Woody, dill and coconut

Oak doesn’t suit every wine the same way. Wine Folly says Pinot Noir and Chardonnay “soak up” French oak flavor readily, while Cabernet Sauvignon absorbs it less readily. For the other big change that often happens in barrel, see our guide to malolactic fermentation.

French vs American oak

Most wine barrels are made from one of two kinds of white oak.

	French oak	American oak
Species	Quercus petraea (sessile oak) for wine barrels	Quercus alba (American white oak)
Where it grows	French national forests such as Tronçais, Bertranges and Bercé	Missouri, Pennsylvania, Virginia and Minnesota
Grain	Fine and tight	Looser
Typical flavor	Subtler oak, spice	Bolder: dill, coconut, vanilla
Staves	Split along the grain	Sawn
Rough barrel price (Wine Folly)	About $850 to $3,600	About $360 to $500

The Lodi Winegrape Commission explains that barrels for wine come from Quercus petraea, while the faster-growing pedunculate oak of the Limousin forest is used mainly for Cognac and Armagnac. French forests are managed over 150 to 200 years under rules dating back to 1669. Wine Folly notes that most American white oak goes into bourbon barrels.

According to Wine Folly, American oak adds ruggedness to clean, fruit-forward New World wines, while French oak adds flavor more subtly. The way the staves are cut matters too. French and Hungarian oak is split along the grain, which the Lodi Winegrape Commission says yields only about 20% of the wood, while denser American oak can be sawn, for about a 40% yield. That is a big part of why French barrels cost more.

Eastern European oak, such as Hungarian oak, sits in between. Wine Folly calls it a midpoint between American and French oak in flavor and lists a price of about $560 to $700 a barrel.

Note: Prices differ by source and change over time. In the Lodi Winegrape Commission’s 2021 article, Tonnellerie Ô quoted French barrels from $995 (three-year seasoned wood) and from $2,000 (five-year), and American oak (two-year) from $545.

Barrel sizes

Barrel	Volume	Notes
Barrique (Bordeaux)	225 liters (about 59.4 US gallons)	The traditional size, per Wine Folly; longer and narrower
Burgundy barrel	About 228 liters (about 60.2 US gallons)	Slightly fatter and shorter, per the International Wine & Food Society
Botti and foudres	About 1,000 to 20,000 liters (about 264 to 5,283 US gallons)	Large casks that give a gentler oak effect

Size changes the effect. “The larger the barrel used, the less oak lactones and oxygen are imparted into a wine,” Wine Folly explains. Some wine rules name the barrel: Rioja, for example, specifies the 225-liter barrel for its aging terms, as our Spanish wine guide explains.

Toast levels

Toasting is the step where the cooper heats the inside of the barrel. Wine Folly describes it as caramelizing the wood’s sugars with fire or radiant heat to develop aroma compounds. The Lodi Winegrape Commission lists the grades cooperages use:

• Blonde (barely toasted)
• Medium
• Medium slow
• Medium plus
• Heavy (darkest)

In our view, it helps to think of it like toasting bread: the longer the toast, the darker the result. Silver Oak Cellars, for example, toasts its American oak barrels for about 40 minutes to a medium-light level.

New vs neutral oak

A new barrel gives the most flavor. Wine Folly says oak flavor extraction drops each time a barrel is used, and that after its first 2 to 3 uses a barrel no longer adds flavor and is considered neutral. A neutral barrel still lets a little oxygen through, so winemakers use it to soften a wine without making it taste oaky. Barrels can stay in use for up to 100 years, according to Wine Folly.

That is why labels and tech sheets often give a percentage of new oak. Wine Folly’s examples:

Wine	Typical barrel regime (Wine Folly)
Pinot Noir	10 months in used French barriques
California Chardonnay	About 50% new French barriques
Bordeaux	50% new French barriques
Zinfandel	20% new barriques of French, American and Hungarian oak
Gran Reserva Rioja	40% American and 60% French oak

Our pick for learning the difference: compare a Chablis, which our Chablis wine guide describes as usually made with less oak than other Chardonnays, with a California Chardonnay aged partly in new oak. In our view, the contrast shows what new oak adds better than any description. Our Zinfandel guide covers the red in Wine Folly’s mixed-oak example.

Oak alternatives: chips and staves

Not every oaky wine sees a barrel. Winemakers can add oak chips, staves or cubes to a tank instead. Wine Folly says these are more efficient, because every side of the wood touches the wine, cheaper, because they use more of each tree, and have a smaller shipping footprint than heavy barrels. The Lodi Winegrape Commission notes that chips and staves can be toasted to similar degrees as barrels. What they don’t give is the barrel’s slow breathing, since the wine sits in a sealed tank.

How wine barrels are made

Making a barrel is called cooperage, and the craftsperson is a cooper. The Lodi Winegrape Commission followed a barrel through Tonnellerie Ô, a cooperage in Benicia, California, and Silver Oak describes how its own cooperage in Higbee, Missouri, builds American oak barrels. The main steps:

1. Growing the tree. Silver Oak says its white oak trees need at least 90 years before harvest. In French forests, trees are graded for uses such as staves at about 150 years, according to the Lodi Winegrape Commission.
2. Cutting staves. The wood is split (French) or sawn (American) into staves, the long curved planks of the barrel. Silver Oak’s barrels use 32 staves.
3. Seasoning. The staves air-dry outdoors; Silver Oak says this softens harsh, raw tannins. The Lodi Winegrape Commission says seasoning usually takes 2 to 3 years, and 4 to 5 for finer barrels, and that the wood should drop below 15% moisture to avoid leaks. Silver Oak seasons its staves for about 24 months.
4. Raising. The cooper sets the tapered staves upright on a table inside temporary hoops, alternating wide and narrow staves to keep the barrel symmetrical, as Tonnellerie Ô does.
5. Bending. The barrel is warmed over a fire so the wood bends without splitting. At Tonnellerie Ô it spends about 25 minutes over the fire, with the staves watered to soften the fibers, before a bending machine presses them together; Silver Oak heats until the outside reaches 300°F.
6. Toasting. The inside is toasted. For one custom order, Tonnellerie Ô applied 180°F heat to reach a blonde toast.
7. Heading. The cooper cuts a groove (the croze) near each end to hold the round heads. Silver Oak says its heads are held in place by pressure, with no glue.
8. Testing. Tonnellerie Ô fills each barrel with about 2 gallons of water, pressurizes it with air and rotates it; leaks are sealed with food-grade paraffin.

Seasoning dominates the timeline: years of drying for a barrel built in a fraction of that time. In our view, that and the low yield of split French oak explain most of the price.

What oak means when you buy wine

Back labels and winery tech sheets often mention barrels in a few standard ways: “aged in French oak”, “50% new oak”, “neutral oak” or “unoaked”. Use them as a rough guide to how woody a wine will be: more new oak and smaller barrels mean more oak flavor; neutral oak or big casks mean less. Barrels replaced clay amphorae partly because they held larger volumes and were easier to store and move, the Lodi Winegrape Commission notes; our history of wine guide covers those earlier jars.