If you\u2019re around winemakers at harvest, you\u2019ll inevitably hear someone say the word Brix. Pronounced \u201cbricks,\u201d it\u2019s an estimation of the sugar content of grape juice or fermenting wine.\r\n\r\n\r\n\r\nIt originated in the 18th century when German scientist Adolf Ferdinand Wenceslaus Brix created a set of standards to accurately measure the sugar (or sucrose) content of liquids. These guidelines are still used in the food and beverage industry today.\u00a0\r\n\r\n\r\n\r\nThe measurement is referred to as \u201cdegree Brix,\u201d abbreviated \u00b0Bx, where each degree equals 1 gram of sugar per 100 grams of liquid. So, you might hear a winemaker say, \u201cI harvested at 23 degrees Brix\u201d or simply, \u201c23 Brix.\u201d\r\n\r\n\r\n\r\nVineyard workers and winemakers measure Brix for an array of reasons.\r\n\r\n\r\n\r\nEvaluating Ripeness\r\n\r\n\r\n\r\nAs harvest approaches, winemakers use Brix as a rough evaluation of grape maturity.\u00a0\r\n\r\n\r\n\r\n\u201cTesting for Brix is fast, and it has the strongest correlation to ripeness of any of the factors that we look at,\u201d says Josh Maloney, who consults for a number of Washington wineries.\r\n\r\n\r\n\r\nWinemakers target a specific range based on variety, region, vintage and house style. Sparkling wines might be picked as low as 17 or 18 Brix, white wines generally 20 to 24 and red wines 22 to 26, though higher numbers are possible. As Brix approach their target range, winemakers know it\u2019s time to taste grapes and think about when to pick.\u00a0\r\n\r\n\r\n\r\n\u201cI usually don't start getting serious about picking until I hit about 24 or 25 [Brix],\u201d Maloney says of his red wines. \u201cI get nervous when it gets above 26. So, it's a fairly narrow window.\u201d\r\n\r\n\r\n\r\nDetermining Potential Alcohol\r\n\r\n\r\n\r\nOnce grapes are harvested, Brix measurements serve a different purpose.\r\n\r\n\r\n\r\n\u201cIt gives us a pretty good reflection of how much sugar is present and, therefore, the potential alcohol of the finished wine,\u201d says Sabrina Lueck, interim director of winemaking at the Institute for Enology and Viticulture at Walla Walla Community College.\r\n\r\n\r\n\r\n\r\nAs grape juice ferments, yeasts convert sugar into alcohol. A simple rule of thumb is Brix multiplied by 0.6 equals potential alcohol, though the actual conversion rate can vary between 0.55 to 0.65. So grapes at 24 Brix, for example, would be expected to have a potential alcohol around 14.4%. Knowing this aids winemaking decisions.\r\n\r\n\r\n\r\n\u201cIt tells me if there might be some adjustments that need to be made,\u201d says David Merfeld, winemaker at Northstar Winery in Walla Walla, Washington.\r\n\r\n\r\n\r\nPotential adjustments include chaptalization, or adding sugar during fermentation to increase potential alcohol in a process. This tends to be done in some cooler regions or vintages.\r\nAlternately, in warmer regions or vintages, winemakers might add water to lower potential alcohol, which is referred to as \u201cwatering back.\u201d The overall goal is to ensure the wine is balanced.\r\n\r\n\r\n\r\nMonitoring Fermentation\r\n\r\n\r\n\r\nAfter crushing grapes, winemakers check Brix daily to monitor fermentation. As yeasts convert sugar to alcohol, Brix drops, slowly at first and then more quickly.\u00a0\r\n\r\n\r\n\r\nIf one is fermenting to dryness, as opposed to leaving residual sugar, Brix readings ultimately go below zero. If Brix stalls before a wine is dry, that means yeasts have stopped converting sugar to alcohol. This is referred to as a \u201cstuck fermentation.\u201d\r\n\r\n\r\n\r\n\u201cIf I go two or three days and the Brix hasn\u2019t changed, there's a problem,\u201d says Merfeld.\u00a0\r\n\r\n\r\n\r\n\r\nHow to Measure Brix\r\n\r\n\r\n\r\nThere are three tools winemakers use to measure Brix. The first is a refractometer, a device that leverages light refracting differently in a liquid based on its density. Most of the density in grape juice comes from sugar.\r\n\r\n\r\n\r\n\u201cIt can only be used before fermentation, but it's fantastically convenient and is a good tool in the vineyard,\u201d says Lueck.\r\n\r\n\r\n\r\nThe second is a hydrometer, used once juice is fermenting. This is a glass tube with a lead weight on the bottom. How high the tube floats reflects density and, therefore, sugar content.\r\n\r\n\r\n\r\nThe last device is a densitometer, which measures density by causing a juice sample to oscillate. This is by far the most expensive of the three. Basic refractometers and hydrometers cost about $20; densitometers can run upward of $3,000.