How to Calculate ABV of Home Brew Beer and Wine
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How do you calculate ABV of home brew?
ABV% = (Original Gravity − Final Gravity) × 131.25. Take your Original Gravity (OG) reading before pitching yeast and your Final Gravity (FG) reading when fermentation is complete. For example: OG 1.050, FG 1.010 → (1.050 − 1.010) × 131.25 = 5.25% ABV. That's all there is to it.
What do you need to calculate ABV?
You need a hydrometer and a trial jar or tall container to take readings in. A hydrometer costs under £4 and lasts indefinitely — it's one of the most important pieces of equipment in any home brewer's kit. Without it, you can't accurately calculate ABV and you can't safely confirm fermentation is complete before bottling.
What is Original Gravity and Final Gravity?
Original Gravity (OG) measures the density of your wort before fermentation — it tells you how much sugar is present. Most standard beer kits start between 1.038–1.050 OG. Final Gravity (FG) measures the density after fermentation is complete — typically 1.006–1.012 for kit beers. The difference between them tells you how much sugar was converted to alcohol.
How do you read a hydrometer correctly?
Fill a trial jar with a sample of your beer. Float the hydrometer without it touching the sides. Read the scale at the bottom of the curved liquid surface (the meniscus) — not where the liquid climbs up the glass. Take readings at 20°C for accuracy; warmer liquid reads lower, cooler reads higher. For full instructions, see our hydrometer guide.
What ABV should home brew beer be?
Most standard 40-pint beer kits produce beer between 3.5% and 5.5% ABV depending on the kit and how much sugar you add. Premium kits like St Peters IPA target around 5.5% ABV. Stouts and bitters typically fall between 4.0–4.9% ABV. You can boost ABV by adding more fermentable sugar, though this can thin the body — spray malt is a better choice for boosting strength with better flavour.
ABV Quick Reference
| OG | FG | ABV% |
|---|---|---|
| 1.040 | 1.008 | 4.2% |
| 1.048 | 1.010 | 5.0% |
| 1.050 | 1.010 | 5.25% |
| 1.055 | 1.012 | 5.6% |
Buy your hydrometer at BrewCo UK. For all common fermentation questions, see our home brew FAQ.