Quadrupel

Put the style guidelines side by side and the series falls apart. According to the BJCP the light monastic table beer (Belgian Single) has 4.8–6% alcohol, a dubbel 6–7.6%, a tripel 7.5–9.5% and a Belgian Dark Strong Ale, the quad, 8–12%. The Brewers Association uses 6.3–7.6% for dubbel, 7.1–10.1% for tripel and 10.0–14.2% for quadrupel. There is no question of a 1:2:3:4 series.

According to the BJCP, tripel and quad even largely overlap. The BJCP calls the quad less bitter and hoppy than a tripel, but about as strong. The real difference is in colour and flavour: a quad is dark, malt-rich and fruity, a tripel blond, dry and spicy.

Where the names dubbel and tripel come from is not known for certain. Quadrupel is a much later extension of the series: as far as is known, La Trappe was the first to use the name, according to the online beer magazine Hop Culture in 1991.

The style is not centuries old. According to the BJCP, Westvleteren began with a strong dark beer just before the Second World War, and Chimay and Rochefort followed just after the war. Some secular breweries have been making such beers since around 1960.

The name is even younger. The BJCP writes that 'Quadruple' is the name of one specific beer. According to the online beer magazine Hop Culture, De Koningshoeven (La Trappe, near Tilburg) released the first beer with the name Quadrupel in 1991. We found no archive source for that; so it remains 'as far as is known'. The BJCP also writes that the term quad is mainly used outside Belgium, and that many examples are simply named after their strength or colour designation.

The BJCP does not treat the quad as a separate style, but as Belgian Dark Strong Ale. The Brewers Association does have a separate category: Belgian-Style Quadrupel.

It is not an exclusively Trappist style either. Besides Trappists, the BJCP also names examples from ordinary breweries, such as St. Bernardus Abt 12 and the American Boulevard The Sixth Glass.

According to the International Trappist Association, Westvleteren 12 has an alcohol percentage of 10.2% and Westvleteren 8 of 8%. The number can therefore coincide with the alcohol percentage or be close to it, but it means something different.

The BJCP writes that many beers in this style are simply known by their strength or colour designation. The beer writer Michael Jackson wrote in 1998 about St. Bernardus that the beers were numbered according to the old Belgian gravity scale. For the Abt 12 he gave more than 10%, for the Pater 6 6.7%.

How that old Belgian scale worked exactly, we could not establish with a primary source. That is why we leave out an explanation of the scale itself here. If you want to know how strong a beer is, look at the alcohol percentage on the label, not at the number in the name.

In May 2025 the abbey Maria Toevlucht in Zundert announced that it would close. There were still six monks, against more than seventy at the peak. Omroep Brabant then called Zundert one of only two Trappist beers that the Netherlands has.

On 31 August 2025 the last brothers left. According to the NOS the brewery closed along with the monastery. A spokesperson for the abbey said that no more Trappist beer would be made, even if the brewery were to stay after all. The label Authentic Trappist Product requires, among other things, that production takes place under the supervision of monks or nuns. In the Netherlands only La Trappe remained as a brewer of Trappist beer.

The current list of the International Trappist Association of products that carry that label (August 2026) names in the Netherlands only Koningshoeven abbey, the abbey of La Trappe. Zundert is no longer on it.