Mead ABV = (original gravity − final gravity) × 131.25. Starting at 1.105 and finishing at 1.010 gives about 12.5%. For nutrients, a one-gallon batch at 1.100 needs about 4 to 4.5 g of Fermaid O in four doses. To backsweeten, each ounce of honey raises one gallon by about 0.002.
The calculators
Planning a batch from scratch? Start with the honey per gallon calculator, which works backwards from the strength and sweetness you want. Use these once you have a starting gravity.
1. Alcohol (ABV) from gravity
2. Yeast nutrient schedule (TOSNA 2.0)
3. Backsweetening
Add about two thirds of the honey, stir gently, wait a day and taste before adding the rest. Always stabilize first, or the yeast will ferment the new honey.
Taking a gravity reading
- Sanitize the hydrometer and test jar, and draw a sample with a sanitized wine thief or turkey baster.
- For the starting reading, stir the must thoroughly first. Honey sinks, and an unmixed sample reads far too low or too high.
- Spin the hydrometer gently to knock off bubbles, then read at the bottom of the meniscus at eye level.
- Most hydrometers are calibrated at 60°F or 68°F. At room temperature the error is only a point or two, but a warm must straight after mixing can be off by five.
- Do not pour the sample back unless everything was sanitized. It is also the best tasting sample you will get.
Fermentation is finished when the reading is the same three days in a row, not when the airlock stops. See how long mead takes to ferment.
Starting gravity to ABV chart
| OG | Honey per gallon | ABV at FG 1.000 | at 1.010 | at 1.020 |
|---|---|---|---|---|
| 1.050 | 1.4 lb | 6.6% | 5.3% | 3.9% |
| 1.070 | 2.0 lb | 9.2% | 7.9% | 6.6% |
| 1.090 | 2.6 lb | 11.8% | 10.5% | 9.2% |
| 1.100 | 2.9 lb | 13.1% | 11.8% | 10.5% |
| 1.110 | 3.1 lb | 14.4% | 13.1% | 11.8% |
| 1.120 | 3.4 lb | 15.8% | 14.4% | 13.1% |
| 1.130 | 3.7 lb | 17.1% | 15.7% | 14.4% |
| 1.140 | 4.0 lb | 18.4% | 17.1% | 15.7% |
For where those numbers sit next to commercial mead, grape wine and beer, and what they mean for calories, see mead alcohol content and calories.
How ABV is calculated
Yeast turn sugar into roughly equal weights of alcohol and carbon dioxide. The gas leaves, and alcohol is lighter than water, so the gravity falls. The standard homebrew formula converts that drop into alcohol:
- Standard: ABV = (OG − FG) × 131.25
- High gravity: ABV = (76.08 × (OG − FG) ÷ (1.775 − OG)) × (FG ÷ 0.794)
The two agree closely for beer-strength batches. Meads often start above 1.100, where the second is more accurate and reads a little higher.
How the nutrient schedule works
Honey is short of the nitrogen yeast needs to build healthy cells. Underfed yeast stall, throw off rotten-egg hydrogen sulfide and leave harsh "rocket fuel" flavors, which is where mead's old reputation for needing years of aging came from. The fix is TOSNA (Tailored Organic Staggered Nutrient Addition), a feeding method popularized in the homebrew community and now the default for most mead makers.
- Target nitrogen: Brix × 10 × the yeast's nitrogen factor (0.75 low, 0.90 medium, 1.25 high) gives the target YAN in parts per million.
- Fermaid O needed: (target YAN ÷ 50) × gallons, in grams. The divisor reflects that yeast use the organic nitrogen in Fermaid O more efficiently than lab YAN figures suggest.
- Timing: four equal doses at 24, 48 and 72 hours, and the 1/3 sugar break or day 7.
- Go-Ferm: used when rehydrating the dry yeast, at about 1.25 g per gram of yeast, in water only (not must).
Which yeast is low, medium or high demand, and why, is covered in our guide to the best yeast for mead.
How the backsweetening math works
One pound of honey adds about 35 gravity points to one gallon, so the honey you need is (target gravity − current gravity) × 1000 × gallons ÷ 35, in pounds. Stabilizing first means potassium sorbate (about 1/2 teaspoon per gallon) plus potassium metabisulfite (one Campden tablet per gallon): sorbate stops the yeast reproducing and sulfite protects against oxidation and spoilage. Wait 24 to 48 hours before adding honey. The whole process, including a one-glass bench trial, is in how to backsweeten mead. The sweetness target that suits each style is covered in sweet vs dry honey wine, and more recipes to practice on are in our mead recipe collection.
Frequently asked questions
How do you calculate the ABV of mead?
Take a hydrometer reading before fermentation (original gravity) and after (final gravity). ABV is roughly (OG minus FG) times 131.25. A mead that starts at 1.105 and finishes at 1.010 is about 12.5% ABV.
Can I measure mead ABV without a hydrometer?
Not accurately. You can estimate the potential alcohol from the amount of honey (about 35 gravity points per pound per gallon), but only a starting and finishing reading tells you what actually fermented. A refractometer works for the starting reading but needs an alcohol correction afterwards.
How much Fermaid O do I need for a gallon of mead?
For a typical one-gallon mead starting around 1.100 with a medium-demand yeast such as 71B or D47, about 4 to 4.5 g in total, split into four doses at 24, 48 and 72 hours and at the 1/3 sugar break.
Does this calculator use TOSNA 2.0 or TOSNA 3.0?
TOSNA 2.0, the formula published by Mead Made Right: Brix times 10, times the yeast nitrogen factor, divided by 50, times gallons. Some online calculators label their schedule TOSNA 3.0. We have not found a published primary source for that version, so this calculator stays with the documented formula and shows its working.
Is there a mead recipe calculator for how much honey to use?
Yes. The honey calculator on our honey-per-gallon page works out the honey for any batch size, strength and sweetness, and every recipe in our collection has a batch-size switch that rescales the ingredients.
What is the 1/3 sugar break?
The point at which a third of the sugar has fermented. For a mead starting at 1.105 it is around 1.070. Yeast take up nitrogen best early, so the last nutrient dose goes in no later than this point.
Why is my mead ABV higher than the standard formula says?
The simple (OG minus FG) x 131.25 formula underestimates strong fermentations. Above about 1.090, the high-gravity formula shown in the calculator is closer; the difference is usually 0.3 to 1 percentage point.
How much honey does it take to raise the gravity of a gallon by 0.010?
About 4.5 oz (0.29 lb). Each ounce of honey adds roughly 0.002 to one gallon.