Priming Sugar Calculator — Homebrew Carbonation Lab

For a 5-gallon batch fermented around 68°F (20°C) carbonated to a typical 2.5 volumes of CO₂, you need about 124 g (4.4 oz) of dextrose (corn sugar) or about 113 g (4.0 oz) of table sugar. That is the standard answer to the "priming sugar for 5 gallons" question — but the exact amount depends on your beer's temperature (which sets the residual CO2 already dissolved) and your target carbonation, so use the calculator above with your numbers instead of a flat rule of thumb. All priming sugar amounts in this tool are shown in grams (plus ounces and approximate cups).

For a 5-gallon batch at 68°F carbonated to 2.5 volumes, each 12 oz bottle needs about 2.3–2.4 g of dextrose (roughly 3/4 teaspoon) or about 2.1–2.2 g of table sugar (roughly 1/2 teaspoon). Use the Per-Bottle Dosing tab for your exact batch size, bottle size, and target volumes — teaspoon measures are approximate, so a small digital scale is more accurate.

Yes. Table sugar (sucrose) is 100% fermentable and works fine for priming — use about 9% less by weight than dextrose (corn sugar), because dextrose is only about 91% as fermentable per gram. The corn sugar vs table sugar debate is mostly tradition: in blind tastings at priming quantities the flavor difference is negligible. Dissolve either sugar in a little boiled water, cool it, and mix gently into the bottling bucket.

Priming sugar in grams is the reliable unit — cups are only an approximation because cup weights vary by sugar and by brand/grind: about 200 g per cup for table sugar, 165 g for dextrose (corn sugar), 340 g for honey, 315 g for maple syrup, 220 g packed for brown sugar, and 150 g for dry malt extract. Volume measures are inconsistent, so the calculator shows cups as an approximation — weighing your sugar is always more accurate.

So what is carbonation? Volumes of CO₂ (also written CO2 volumes) is the standard unit: 1 volume means the beer holds as much dissolved CO₂ as its own volume at standard conditions. Typical targets run from about 1.5 volumes for a British bitter, 2.2–2.7 for most American ales and lagers, up to 2.8–3.5 for wheat beers and saisons. Higher volumes need pressure-rated bottles.

Colder beer holds more dissolved CO₂ from fermentation (residual CO₂), so it needs less priming sugar; warmer beer holds less and needs more. Use the highest temperature the beer reached after fermentation finished, not the current cold-crash temperature. The calculator estimates residual CO₂ from temperature with the standard published curve (about 0.86 volumes at 68°F / 20°C) and subtracts it from your target.

How long to carbonate beer in bottles? Typically 2–3 weeks at around 68–72°F (20–22°C) to fully carbonate, plus another few days chilled in the fridge so the CO₂ dissolves into the beer instead of foaming out. High-alcohol or cold-stored beers can take longer because the yeast work more slowly.

With the set-and-forget method — regulator at the chart PSI for your temperature and target volumes — a keg carbonates in about 7–10 days. Burst carbonation (30–35 PSI for 24–36 hours, then purged down to serving pressure and rested 2–3 days) gets you there in 2–4 days total. Shaking or rolling the keg is fastest (hours) but the easiest way to overshoot.

It depends on beer temperature and target volumes: for example about 10–11 PSI at 40°F (4°C) for 2.5 volumes, or about 15 PSI at 45°F (7°C) for 2.7 volumes. Use the Force Carbonation Lab tab or the interactive PSI chart — set the regulator to that pressure and leave it a week for set-and-forget carbonation.

A bottle bomb is a bottle that explodes from excess CO₂ pressure — usually from too much priming sugar, bottling before fermentation finished, or an infection that ferments leftover sugars. Avoid them: verify final gravity is stable over 2–3 days before priming, weigh (don't scoop) your sugar, stay under about 3.0 volumes in standard longneck bottles, use champagne or Belgian bottles with wire cages for higher carbonation, and never carbonate in wine bottles.

Because they contain water and unfermentable compounds, you need more by weight than plain sugar: honey priming uses about 78% effectiveness relative to table sugar and maple syrup about 65%. For the classic 5-gallon / 68°F / 2.5-volume example that is roughly 145 g of honey or 174 g of maple syrup. Honey and syrup vary by variety and brand, so treat these as estimates and keep carbonation moderate when using them.

Carbonation drops are pre-measured doses of dextrose/sucrose for one 12 oz (or 375 ml) bottle — convenient and consistent, but a fixed dose and more expensive per batch. Weighed priming sugar is cheaper and lets you hit any target volume and any bottle size. For mixed bottle sizes or precise styles, the calculator's per-bottle mode wins.

Five US gallons is 640 fluid ounces, which fills about 53 twelve-ounce bottles with zero loss. After typical trub and racking losses of around half a gallon you will fill about 48 bottles. The Per-Bottle Dosing tab computes this for any bottle size with your own loss figure.

How long to ferment beer before bottling? Bottle by gravity, not by calendar: take hydrometer readings 2–3 days apart and bottle only when the final gravity is completely stable. Most ales finish in 1–3 weeks, lagers and strong beers longer. Bottling an unfinished fermentation is the most common cause of bottle bombs, because the remaining sugars add CO₂ on top of your priming sugar.

How long after bottling is beer good? Most bottle-conditioned beers are best within 3–6 months stored cool and dark. Hop-forward styles like IPAs fade fastest — drink them fresh. Strong, dark styles (stouts, barleywines, Belgian strong ales) can improve with age for a year or more if stored properly.

Yes. This tool runs 100% in your browser — every calculation happens locally in JavaScript and nothing you enter is sent to any server. There are no accounts, no tracking of your inputs, and it works offline once the page is loaded.