Same bag of beans can taste bright and sour on Tuesday and heavy and bitter on Friday. Brew Ratio is a kitchen-laboratory notebook for that gap. You log dose, water or beverage weight, temperature, grind, and total time. The bench then places the cup on a brew ratio, a concentrate ratio, and an estimated extraction-yield range drawn from a published kitchen formula, not from a refractometer. A Gold Cup ring shows whether the estimate sits under, inside, or over the 18 to 22 percent band. Reverse mode starts from the cup you want and walks back to grams and household spoon counts. Tune mode turns a sour or bitter note into three numbered moves — grind clicks, degrees, seconds — scaled to how far the estimate sits from the band. Gear templates for pour over, immersion press, moka pot, and cold brew keep the kit honest. A bean cabinet remembers roast, date, and flavor so the recipe that actually worked on this kettle is still visible months later. Everything stays on the phone.
