All Grain OG, FG, ABV Calculator
This tool exists to eliminate the guesswork from your brew day.
By synchronizing your grain bill with your specific system efficiency and volumes, it translates raw ingredients into precise gravity and alcohol predictions.
Use it to lock in your Pre-Boil targets, ensure your Original Gravity hits the style, and guarantee your ABV lands exactly where you planned - before you even crack a bag of grain.
Batch Data
Grain Bill
Add your grains and weights. Potential is an average typical yield (PPG).| Weight | Grain | Potential |
|---|
Calculated Recipe Targets
Using This Tool Like a Master Brewer
1. Reverse Engineer the Recipe
Don't just type in a recipe and blindly accept the result. Use the tool backwards: enter your target OG first (e.g., 1.050 for a Pale Ale). Then, adjust your base malt weight up or down until the "Est. OG" result matches your target.
This ensures you are brewing to the specific constraints of your system, rather than just following a generic recipe sheet.
2. Calibrate Your Efficiency
A Master Brewer doesn't guess their efficiency; they track it. While 75% is a good starting point, the "Efficiency" field is your variable for truth.
If you consistently miss your gravity numbers low, drop this setting to 68% or 70% for your next batch.
This calculator is only as accurate as your understanding of your own gear's losses.
3. The Pre-Boil Checkpoint
The most valuable number here isn't the final ABV - it's the "Est. Pre-Boil OG." This is your safety net. Measure your gravity right before the boil starts.
If it matches this calculator's prediction, your final beer will be perfect. If it's low, you know now (not two weeks later) that you need to extend the boil or add some DME to save the batch.
The Architecture of the Grain Bill
All-grain brewing is, fundamentally, an extraction exercise. We are washing sugar off of crushed husks with hot water.
This calculator represents the blueprint of that extraction. Without it, you are essentially building a house without a tape measure.
You might end up with something that stands, but the proportions will likely be off. By engaging with these numbers before you heat your strike water, you move from "making soup" to "engineering flavor."
The primary advantage of this predictive approach is consistency.
If you know that your system yields exactly 72% efficiency, you can take a recipe designed for a massive commercial brewery and scale it perfectly to your 5-gallon Igloo cooler. You aren't just guessing; you are translating.
You know that 10 pounds of Maris Otter will yield a specific gravity of 1.052 on your system every single time. That repeatability is the hallmark of a master brewer.
However, the downside - or rather, the pitfall - is treating the calculator as a guarantee rather than a model. Real-world brewing involves variables that math cannot always predict. Channeling in the mash tun, humidity affecting boil-off rates, or trub losses in the kettle can all skew the final numbers.
The "ins and outs" of efficiency often come down to the quality of your crush (shown above). If your mill gap is too wide, you leave sugar behind in the grain, lowering your efficiency. If it is too fine, you risk a stuck sparge. The calculator assumes a "standard" crush; your mill dictates the reality.
Furthermore, the "ins and outs" of the final ABV are determined by the boil itself. This is where everything concentrates. The shift from Pre-Boil Gravity to Original Gravity is purely a function of evaporation.
Understanding your system's boil-off rate allows you to hit your volume and ABV simultaneously. If you boil too hard, you end up with less beer that is stronger than intended. If you simmer too gently, you end up with diluted, weak beer.
Ultimately, these numbers are targets, not immutable laws.
Use the calculator to set your path, but use your hydrometer and thermometer to navigate the journey. If you miss your Pre-Boil gravity, don't panic - adjust. Boil longer, add water, or tweak your hop schedule. The calculator gives you the map, but you are the one driving the brew day.