Residual Sugar in Wine: How to Convert a Percentage to Grams Per Liter and Visaversa

The amount of residual sugar (RS) in wine can be reported either in grams per liter (g/L) or as a percentage (%). They are just two ways of specifying the same sugar concentration. But, how are the two measures related? Well, it’s actually quite simple to do the conversion.

When a wine’s residual sugar is reported in grams per liter, it specifies the grams of sugar in 100 mL of wine. This is so because a percentage is expressed per hundred. So, to briefly get a bit mathematical, since 1 liter is 1,000 milliliters, if you have a wine with a given number of grams per liter of residual sugar, you have to divide that number by 10 to to get the value per 100 milliliters so that it can be expressed as a percentage.

Simply put:

  • To convert grams per liter to a percentage: % sugar = grams per liter divided by 10

    • % Sugar = g/L ÷ 10

  • To convert a percentage to grams per liter: Grams/L = Percentage x 10

    • g/L = % x 10

So, a wine 5 g/L of residual sugar is 0.5% sugar (5 ÷ 10) and a wine that has 2% residual sugar has 20 g/L (2 x 10 = 20 g/L)

Here are some typical amounts of residual sugar in typical wines:


Ever Wonder? What Makes Some Wines Sweet?

In wines, there is a wide spectrum of sweetness. Those that are not sweet are referred to as “dry” wines while those that are sweet are simple referred to as “sweet” wines. And, in the wine world, this all has to do with ‘residual sugar.’

When wine grapes are ready for harvest, one of the primary indicators to the winemakers is their sugar content. Using a device called a refractometer, they are able to analyze a drop of grape juice and determine its sugar content. By passing light through the juice and measuring the refraction (i.e., the amount that the light bends), the sugar content can be measured. This is referred to as Brix.

So, in simple terms, when the grapes are ready to be harvested they have ‘just the right amount’ of sugar. Anyone who’s had a glass of grape juice with breakfast knows that grape juice is naturally sweet. And, this natural sugar in the grape juice is the key to fermentation. Yeast is added to the grape juice and the live yeast feed on the sugar and converts it to alcohol. And, in general terms, once all the sugar is eaten up, fermentation ends.

But, wine makers have some control over this process. They can allow fermentation to go to the end which means that there is little to no ‘residual sugar’ in the juice that’s now wine. This is the ‘dry’ wine. But, if the fermentation is halted, or only a small amount of yeast is added to the juice, the wine ends up with significant ‘residual sugar.’ And, this results in a ‘sweet’ wine.

That’s a quick overview of sweetness in wine. For further reading, check out these past blogs:

Not All Rosé Wine is Sweet

I’ve heard it over and over - “I don’t drink rosé…it’s too sweet.” But, that’s not always the case.

Unfortunately, rosé wine’s reputations got ruined in the 1970s with wines such as Mateus, Lancers and especially White Zinfandel. Those are the stereotype rosé wines. And, yes, they were more like strawberry soda pop (hence its popularity). Not that there is anything wrong with strawberry soda or that style of white Zinfandel, it’s just that not all rosé wines are sweet. In fact, most bottles of rosé wine being sold today are not actually sweet.

While our brain naturally associates fruit aromas and flavors with sweetness, they are often not directly associated with each other when it comes to wine. Many rosé wines have aromas and flavors of tropical fruits (pineapple, mango) and red fruits (strawberries, cherries, cranberries, raspberries). These wine flavors and aromas may be processed and interpreted by your brain as being “sweet.” But, that doesn’t necessarily mean that it is sweet.

For a wine to be sweet, it must have sugar in it. In the wine world, it’s referred to as residual sugars (RS). That is, natural sugar from the grape’s juice that is not converted to alcohol during fermentation. But, most wines on the store shelf are “Dry” meaning they have a very small amount of residual sugar (1-10 g/L RS).

Today you can find a lot of very nice dry rosés being produced around the world. So try a dry rosé. They are actually not sweet. Cheers!

Ever Wonder? Why are Wines Referred to as Dry?

You may have heard of wines being described as “dry.” When I started out learning about wines, I was told that the best wines are dry wines. But what does that really mean?  The problem is that the term can mean a couple of different things.

Some people will refer to a wine as being dry because of the way that it tastes or the sensation that the wine produces in their mouth.  And, yes, wines can make your mouth feel dry.

The sensation of dryness in the mouth is actually the result of tannic compounds in the wine or 'the tannins.'  Tannins come from the skins and seeds of the grape. And these tannic compounds are the same ones that you experience when you drink a strong cup of tea or when you eat nuts such as walnuts.  They yield the same effect; a drying sensation in the mouth.

But 'dry' generally refers to the lack of residual sugar in a wine. That is, during the fermentation process, the yeast is allowed to consume all the natural sugar in the juice of the grape and convert it into alcohol. Thus, dry wines actually contain little to no sugar.  If the fermentation process is interrupted before the natural sugars are converted to alcohol, then you end up with a wine that has a residual sugar level greater than zero.  These wines are referred to as being ‘off-dry'.’

Now, the question that still don’t know the answer to is why the word ‘dry’ became synonymous with wines of low or no residual sugar. But, I’ll keep digging!

Cheers!

Confusing Sweetness and Fruitiness in Wine

Many wine drinkers may confuse the taste sensations of sweet and fruity. While our brain naturally associates fruit aromas and flavors with sweetness, they are often not directly associated with each other when it comes to wine.

“Fruity” is a term that gets used to describe a wine that has pronounced flavors or aromas of fruits. With wines, you may experience aromas and flavors of citrus (lemon, lime, orange), orchard fruits (apples, pears), stone fruits (apricots, peaches, plums), tropical fruits (pineapple, mango), red fruits (strawberries, cherries, cranberries, raspberries), or dark fruits (blackberries, blueberries, black currant). These wine flavors and aromas may be processed and interpreted as being “sweet.” But, fruity wines aren’t necessarily sweet. Sauvignon Blanc is a good example. While it offers bright fruit flavors of grapefruit, lime, pear and peach, it is typically low in residual sugar.

For a wine to be sweet, it must have residual sugars (RS). That is, sugar that is intentionally left in the juice that doesn’t get converted to alcohol during fermentation. The categories of wine sweetness include “Dry” (1-10 g/L RS), “Off Dry” (10-35 g/L RS), “Sweet” (35-120 g/L RS) and “Very Sweet” (120+ g/L RS).

Most wines on the store shelf are “Dry” but if you’re looking for sweeter white wines look for Kabinett or Spätlese Riesling, Chenin Blanc or Gewürztraminer. Lambrusco is a sweeter, sparkling red wine. Sweeter red wines, by brand, include Ménage á Trois Red (12 g/L RS), Apothic Red (15 g/L RS), Cocobon Red Blend (12 g/L RS), Yellow Tail Shiraz (12 g/L RS) and Jam Jar (57 g/L RS).

So, don’t be fooled. “Fruity” wine traits don’t necessarily mean it’s a sweet wine. Cheers!