grapestompers - winemaking supplies and wine kits
Search Products
Shopping Truck
Winemaking Information
Customer's Corner
Contact Us
About Us

How to Chaptalize Must / Wine

What is chaptalization? | Why is it important to chaptalize?
Hints for chaptalization | Conclusion | References

Ask any experienced winemaker about factors that can come into play to make each year's harvest unique, and there's a good chance mention will be made to the local growing conditions or climate. Some years, the fruit will be fully ripe and bursting with flavor - while in other years (especially during poor growing conditions), the fruit seems like it takes forever to ripen and the harvestable quantity is diminished.

It doesn't take a genius to figure out that wine made from two diverse growing seasons requires different must adjustments in order to make good wine year in and year out. If you've ever made blackberry wine according to your grandfather's old recipe and wondered why one year's wine is great but the next one isn't, one possible explanation is that the sugar content of the blackberry must varied widely from one year to the next.

To get consistent results, vintners test the raw fruit juice to determine the must's quality - and based on the results of these tests, make the necessary chemical adjustments to ensure a well-balanced wine.

This winemaking article will focus on one aspect of creating a well-balanced wine - controlling the alcoholic content of your wine. The amount of alcohol that is in your finished wine is directly proportional to the amount of sugar found in the raw fruit juice, or must. This makes sense, since we know that wine yeast converts the sugar to alcohol and carbon dioxide. The more sugar you have, the more alcohol you'll get. This article does not go into any great detail to discuss other methods of adjusting your must, such as adjusting your acidity and pH.

This article is intended for home winemakers who make their own wine from scratch (from fresh grapes or fruit). If you make wines from kits, you will certainly benefit from this knowledge, but you won't have to worry about chaptalization since modern wine kits are already chemically balanced for consistency.

What is chaptalization?
Simply put, chaptalization (also known as "sugaring") is the procedure of adding sugar to grape juice or must prior to or during fermentation. As you have already surmised, winemakers chaptalize must to compensate for poor growing seasons, or if they're located in areas of the world that experience cooler climates.

By boosting the sugar content to appropriate levels, you can help ensure your wine is well-balanced... but be careful - adding too much sugar is just as bad as not having enough!

Why is it important to chaptalize?
The main reason it is desirable to chaptalize your wine is that your wine will have the proper alcoholic content to help ensure a well-balanced wine.

There are three aspects of must you should measure and adjust (if necessary) prior to pitching the yeast. They are acidity, pH, and the amount of sugar. These three aspects of wine work together to create the taste of the wine. If only one of these readings is out of whack, the wine that is made from that particular batch of must is said to be "out of balance" and the overall taste of the wine will suffer. If the wine is too acidic, it will taste like battery acid; if it doesn't contain enough alcohol, the wine will taste thin. Properly balanced wines have the right amount of pH, acids, and alcohol and taste great. As previously noted, we will concern ourselves solely with the adjustment of sugar in this article.

While we're on the subject, here are some other benefits of chaptalization:

  • Your wine will be less susceptible to spoilage. The lower the alcoholic content, the greater the possibility that your wine could fall victim to harmful mold or bacteria. By keeping your wine at or above 10% alcohol by volume, this type of spoilage is largely prevented.
  • The physical process of chaptalizing involves stirring the must; stirring provides an intangible benefit to your wine, since it helps ensure your must is well mixed and ready to accept the yeast.
  • It forces you to take a close look at your sugar levels; recording your starting specific gravity is a good habit to get into, and can help you reproduce a great wine year after year.

Hints for chaptalization
In a nutshell, here are the processes you would go through to chaptalize wine:

  1. Create the must by getting the juice from your grapes or other fruit
  2. Take a hydrometer reading
  3. Compare the hydrometer reading to your desired specific gravity
  4. Make appropriate sugar additions to must
  5. Pitch yeast to start fermentation

We will visit each of these points in the paragraphs that follow.

The first thing to do is to generate the must. Mostly, this involves squeezing the fruit to get the juice flowing! Once your must is in the fermentation vessel (for most home winemakers making small batches, the fermentation vessel at this point is a food-grade plastic bucket), take a specific gravity reading with your hydrometer.

Note: A hydrometer is a simple, inexpensive piece of testing equipment used by winemakers to determine the amount of sugar available in the must. If you're not familiar with its use, please check out a complementary article entitled "How to Use a Hydrometer" before going any further.

Take the specific gravity reading and see where it falls in the chart below.


Sugar in One
Gallon of Must


Alcohol (%)


0 lb.14 oz.




1 lb. 0 oz.




1 lb. 2 oz.




1 lb. 3 oz.




1 lb. 5 oz.




1 lb. 7 oz.




1 lb. 8 oz.




1 lb. 10 oz.




1 lb. 11 oz.




1 lb. 14 oz.




2 lb. 0 oz.




2 lb. 1 oz.




2 lb. 3 oz.




2 lb. 5 oz.



For white wines, your target specific gravity should probably be in the 1.085 to 1.090 range. If allowed to ferment to dryness, this would equate to a wine that contains about 11.5% to 12% alcohol. For red wines, your desired starting specific gravity would be around 1.090 or 1.095.

For the sake of illustration, let's say you've prepared 6 US gallons of must and took a hydrometer reading. After making corrections to the reading based on the temperature of the must (most hydrometers are calibrated at 60 degrees Fahrenheit), you discover that your red wine's starting specific gravity is 1.070. Since we're making a red wine, our desired starting specific gravity is 1.090.

So how much sugar should we add? Not only that, but what kind of sugar should be used?

Luckily, just plain old white granulated sugar - the kind you buy in the grocery store - is the sugar of choice. It doesn't matter if it came from sugar beets, sugar cane, or whatever. Just don't use brown sugar, since it contains molasses and will really throw off your taste.

We can tell from the chart that must with an SG (specific gravity) reading of 1.070 contains one pound and a half of sugar per gallon. To discover how much sugar is present in the raw must, then, we would simply multiply one and a half pounds by 6. We do this since (at least in this example) we're dealing with 6 gallons of must:

1.5 lbs. per gallon  X  6 gallons = 9 lbs of sugar

Our desired starting SG is 1.090, which is equivalent to 2 pounds of sugar per US gallon:

2.0 lbs per gallon  X  6 gallons = 12 lbs. of sugar

The difference between the two, then, is the amount of sugar to add to bring our must to the desired starting SG:

12 lbs. - 9 lbs. = 3 lbs. of sugar

Our math tells us we need to add 3 pounds of sugar to bring the must up to standard. This is a good original estimate to start with, but I would suggest you err on the side of caution, and add a bit less than this - at least initially until you get some verification from your follow-up hydrometer readings. Why? Well, you can always add more sugar if you need to, but you cannot take it out once it's been put in!

As my personal rule of thumb, I only add 85% of the calculated sugar to my must the first time around. I figure I can always add sugar more later, if my subsequent hydrometer reading tells me so.

Most hydrometers, besides telling you the specific gravity of your must, will also offer a scale which tells you how many ounces of sugar (per US gallon) are contained in your sample. You could alternatively calculate the amount of sugar to add using this scale and applying some simple math.

Using a similar starting SG of 1.070, my own trusty hydrometer tells me that I would need to add about 7 ounces of sugar per gallon to get to my desired SG of 1.090 for my six gallon batch. When I do the math, 6 times 7 oz. equals 42 ounces of sugar to add. This is 6 ounces less than the amount of sugar I determined from the first calculation. After doing the calculation this way, it's easy to see why I always err on the side of caution, and add 15% less sugar than is initially called for by the chart shown, until I am sure what the resulting SG will be.

All right, now it's time to add the sugar to your must. DO NOT simply dump the sugar in your must; my experience is that sugar does not always fully dissolve as fast as you want it to, especially if the liquid you're mixing it with is only at room temperature. If you're impatient and try to chaptalize too quickly, you will accidentally add too much sugar since some of it won't dissolve into solution until after you've gone away.

I recommend removing a bit of strained must (no solids) and warming it slightly in a sanitized saucepan on the stovetop. Do not allow the mixture to smoke or boil. Add sugar slowly, and stir with a sanitized spoon until it is completely dissolved. Once the liquid is cooled, you can re-introduce the sugared must to the rest of the batch. Then stir like crazy to ensure proper mixing.

Finally, treat your must for other issues (pH, acidity), add some food for your yeast, then rehydrate and pitch your yeast to kick off fermentation.

Other factors to consider during chaptalization
Besides simply adjusting the amount of sugar in your must, there are other things you should consider. Among them:

  • When you add sugar to must, the overall volume of the liquid will also increase. Be careful you don't overflow your carboy at the first racking!
  • Be sure all your testing equipment (hydrometers, test jars, spoons, etc.) are properly sanitized before coming into contact with the must. Learn more about winemaking sanitation.
  • Do not simply dump the sugar in your must. Introduce it in the manner specified to prevent shocking your wine yeast.
  • In the case where sugar is added to the must because the fruit is slightly underripe, pay particular attention to the acid level in your must. Fruit that is not ripe has a higher acid content than fully ripe fruit, so you will likely need to adjust the acidity of your must to an appropriate level before you pitch the yeast.
  • If you mess up and add too much sugar during chaptalization, you increase the chances of a stuck fermentation; most wine yeasts can't support further fermentation if the alcoholic percentage is too high. Read our accompanying article about how to prevent or cure a stuck fermentation.

If you're making a wine from scratch, checking the must's specific gravity - which provides an indication of sugar content - before you pitch the yeast is one of the best first steps to ensure a well-balanced wine. If your must doesn't contain the requisite amount of sugars from the start, the alcoholic content of your wine will be lower than you expected - and the wine may taste "off".

Should your hydrometer readings indicate that the starting specific gravity isn't high enough to produce a balanced wine, you should add sugar (chaptalize) to the must and build up the sugar content according to the methods described in this article.

Clicking on any of the reference links below will open a new browser window: