Brewing calculators.
Four tools that do the arithmetic brewing keeps asking for. They run entirely in your browser — no sign-up, no account, nothing sent anywhere.
Which one you need
| The problem | The tool |
|---|---|
| "This recipe says 22 clicks but I have a different grinder" | Grinder converter |
| "I have 17 g left in the bag — how much water?" | Brew ratio |
| "My refractometer says 1.42 — is that good?" | Extraction yield |
| "I want to brew 4:6 but not at 20 g" | 4:6 calculator |
| "It tastes sour and I do not know why" | Dial-in guide |
Strength and extraction are different problems
Nearly every one of these tools exists to hold that distinction steady. Grind controls extraction — whether the cup tastes sour, balanced or bitter. Ratio controls strength — whether there is too much or too little of those flavours. A cup that is balanced but watery does not need a finer grind; it needs a tighter ratio. Getting this backwards is why the same coffee gets solved three times.
These calculations are a small part of what Coffee Aeye does on every brew, against the actual bag in your hand: recipes scaled to your dose, grind quoted in your grinder's own numbers, and a rating that turns into a concrete next move. All of it on-device. Get it on Google Play — €4.29, one-time, no subscription.