Yield of grapes harvested during the grape harvest, usually expressed in hectolitres of grape must or wine per hectare or in kilograms of grapes per hectare. Overseas, tons/acre is also commonly used. This is also used as a wine law specification, expressed as a maximum yield in hectolitres per hectare, for certain wine quality levels and can vary greatly depending on the country, wine-growing region, individual vineyards or even specific wines. In terms of vine density, there has been an extreme reduction over the last two millennia.

The Romans still recommended 50,000 vines per hectare; this ruled out mechanical cultivation from the outset. In the middle of the 19th century, the average density was still 20,000 vines/hectare, with yields of no more than 40 hectolitres/hectare. Today, the vines are planted 1.5 to 2 metres apart (depending on the country and wine-growing region, as well as any regional requirements).

Yields per vine

As a rule, an average of 5,000 vines/hectare are planted (see vine training). One vine yields 1.5 to 2.5 kg of grapes for reduced-yield quality wine, which results in 1.5 to 2 bottles of wine of 0.75 litres each. For specialities such as Beerenauslese, Trockenbeerenauslese or Eiswein, it is considerably less. For the grape varieties grown in Germany and Austria, an average of 55 to 75 litres of must can be expected from 100 kilograms of grapes at normal ripeness. The yield quantity and grape quality is controlled in the vineyard by the winegrower through various measures throughout the year, including pruning and foliage care, as well as thinning out (green harvest) and grape division or grape breakage.

Calculation formula

The yield per hectare (in kilograms) can be calculated using a simple formula: Average number of grapes per vine × average grape weight (in kilograms) × number of vines per hectare = yield in kg/ha.

A more precise calculation takes additional factors into account. The formula is: number of eyes per vine × budding rate (in per cent) × average number of grapes per shoot × average grape weight (in grams) × number of vines per hectare, divided by 1000 = yield in kilograms per hectare. An example calculation:

• 12 eyes per vine
• 90 % budding rate
• 2.2 grapes per shoot
• 120 grams grape weight
• 5,000 vines per hectare

Calculation: 12 × 90 × 2.2 × 120 × 5,000 ÷ 1000 = 14,256...