The standard dose is one crushed Campden tablet per gallon of wine

One Campden tablet per gallon is the baseline for most winemaking. Crush it first, dissolve it in a small amount of wine or water, then stir it into your batch. The tablet releases sulfur dioxide gas, which stops wild yeast and bacteria from spoiling your wine.

This dose works for wine at any stage — when you first crush the grapes, when you rack (transfer) the wine to a clean carboy, or before bottling. The timing and purpose change, but the amount stays the same.

If you are working with a smaller batch — say, a one-gallon carboy instead of a five-gallon demijohn — you will need to break a tablet into pieces. One tablet contains roughly 150 parts per million (ppm) of sulfur dioxide when dissolved in a gallon. That is the target strength for most home winemaking.

Key Takeaways

  • Use one crushed Campden tablet per gallon of wine, whether you are treating fresh juice, racking, or bottling.
  • Crush the tablet and dissolve it in a small amount of wine or water before stirring it into the batch so it distributes evenly.
  • For batches smaller than one gallon, break the tablet into proportional pieces — a quarter tablet for a quarter gallon, for example.
  • Campden tablets work best when added at the start of fermentation and again before bottling to prevent oxidation and spoilage.
  • Wait 24 hours after adding Campden before pitching yeast, because the sulfur dioxide can slow or stop fermentation if the timing overlaps.

Why the timing matters: before yeast and before bottling

The first dose goes in when you crush the grapes or when you first receive juice. This kills off wild yeast and bacteria that could turn your wine to vinegar. Add one tablet per gallon, wait 24 hours, then pitch your cultured yeast. The 24-hour window lets the sulfur dioxide do its job without interfering with fermentation.

The second dose goes in just before bottling. By this point, fermentation is done and the wine is stable. One tablet per gallon again protects against oxidation and any stray microbes that might have entered during racking. This dose extends shelf life, especially if the bottles will sit for months or years before opening.

Some winemakers add a third dose when they rack the wine off the sediment (called the "lees") partway through aging. This is optional and depends on how long you plan to age and how much you worry about oxidation. If you do it, use the same one-tablet-per-gallon rule.

Adjusting for batch size and partial tablets

A full Campden tablet is designed for one gallon. If your batch is five gallons, use five tablets. If it is ten gallons, use ten. The math is straightforward.

Smaller batches require you to divide. A half-gallon batch needs half a tablet. A quarter-gallon (common for test batches) needs a quarter tablet. The easiest way is to crush the tablet into powder on a clean surface, divide the powder into equal piles, and use the pile that matches your batch size. It does not have to be exact — being off by a small amount will not ruin the wine.

If you are making wine regularly, some suppliers sell pre-measured packets of crushed Campden in smaller doses, which removes the guesswork. These are more expensive per tablet but save time and waste.

How to add Campden tablets without clumping

Never drop a whole tablet into your wine. It will not dissolve evenly and may leave undissolved bits floating in the batch. Instead, place the tablet on a clean, hard surface and crush it with the back of a spoon or a mortar and pestle until it becomes a fine powder.

Pour a small amount of the wine you are treating (about a quarter cup) into a separate cup. Add the crushed powder to this small amount and stir for 30 seconds until it dissolves. Then pour the mixture back into the main batch and stir the whole thing for a minute to distribute the sulfur dioxide evenly.

If you are treating juice that has not fermented yet, you can use water instead of wine to dissolve the tablet. The result is the same.

What happens if you use too much or too little

Too little Campden (less than one tablet per gallon) leaves your wine vulnerable to oxidation and microbial spoilage. The wine may turn brown, develop off-flavors, or turn to vinegar if bacteria take hold.

Too much Campden (significantly more than one tablet per gallon) can leave a noticeable sulfur smell or taste in the finished wine. This is called a "sulfur nose" and usually fades over weeks or months as the excess gas escapes, but it is unpleasant to drink when ready. Most home winemakers stick to the one-per-gallon rule and do not exceed it.

If you accidentally add extra tablets, do not panic. The wine is not ruined. Open the carboy or bottle and let it sit with the cap off for a few hours to let excess gas escape. The smell will diminish.

Campden tablets versus potassium metabisulfite powder

Campden tablets and potassium metabisulfite powder do the same job — they both release sulfur dioxide — but they are measured differently. One Campden tablet is roughly equivalent to one-quarter teaspoon of potassium metabisulfite powder, though this varies slightly by brand and purity.

Tablets are easier for beginners because they are pre-measured and require no scale. Powder is cheaper per dose if you make wine regularly, but you need a kitchen scale to measure accurately. If you switch from tablets to powder, check the supplier's conversion chart, because different brands have slightly different concentrations.

For the purposes of this guide, stick with tablets if you are starting out. The one-per-gallon rule is straightforward and reliable.

Storage and shelf life of Campden tablets

Campden tablets lose potency over time, especially if exposed to air, moisture, or heat. Store them in an airtight container in a cool, dark place — a kitchen cupboard away from the stove works fine. A sealed jar in the refrigerator is even better if you have the space.

Tablets that are more than two or three years old may not work as well. If you buy a large supply and do not use them quickly, write the purchase date on the container so you know when to replace them. Most home winemakers buy a small bottle (usually 100 tablets) and use them up within a year or two, so this is rarely a problem.

Frequently Asked Questions

Can I use Campden tablets if I am allergic to sulfites?

No. Campden tablets release sulfur dioxide, which converts to sulfites in wine. If you have a sulfite allergy or sensitivity, you cannot use them. Some winemakers use alternative preservatives like sorbic acid, but these work differently and require different dosing. Consult a winemaking guide specific to sulfite-free methods.

What if I forget to add Campden before pitching yeast?

If you pitch yeast and then remember you skipped the Campden, do not add it now. The yeast is already working and sulfur dioxide will slow or stop fermentation. Wait until fermentation is complete, then add one tablet per gallon before bottling. The wine may be at slightly higher risk of spoilage, but it is not lost.

Do I need Campden tablets if I am using a wine kit?

Most commercial wine kits include Campden tablets or a pre-measured sulfite solution in the box. Follow the kit instructions for when and how much to use. Do not add extra unless the instructions say to. If your kit does not include them and you want to add them anyway, one tablet per gallon at the start and before bottling is the standard dose.

How long does it take for Campden to work?

Campden tablets release sulfur dioxide within minutes of dissolving, and the gas begins killing wild yeast and bacteria when ready. However, the process is not instantaneous. Waiting 24 hours before pitching cultured yeast gives the sulfur dioxide time to do its job thoroughly before you introduce the yeast you want to ferment the wine.

Can I use Campden tablets in the middle of fermentation?

It is not recommended. Adding Campden while yeast is actively fermenting can slow or stop fermentation, which leaves residual sugar in the wine and risks spoilage. If you need to stop fermentation early (for example, to make a sweet wine), Campden can help, but this is an advanced technique. Stick to adding it at the start and before bottling for straightforward winemaking.