Calculator
How many grams of coffee and water does this cup need? Type the dose and the ratio; add a TDS reading if you own a refractometer and it works out the extraction too.
Open the toolEight tools, none of them a black box
Coffee tools
Every one shows its formula, labels what it assumed and keeps whatever you type on this device.
Ratio chart
Which ratio does my brewer usually begin at? One row per method, and any row scales to the dose you type.
Open the toolGrind size
How fine for this method, and where does my setting land if I switch methods? It answers in ranges, because no two grinders agree.
Open the toolCaffeine
Roughly how much caffeine is in the cup I just made? A low and a high figure from the grams you used and the species of bean.
Open the toolMilk drinks
How much espresso, milk and foam for my own cup? Pick the drink, give the cup size and read the split.
Open the toolCold brew
How much coffee for this jar, and how far do I dilute the concentrate when I serve it?
Open the toolBrew water
How much tap water and how much distilled water to reach a mineral figure I measured? Arithmetic only, with no promise about taste.
Open the toolBrew timer
What do I pour next, and when? It walks a recipe one step at a time and picks up again after a reload.
Open the toolBefore the kettle boils
New brewer, or a method you have not tried? Read its row on the ratio chart first, then let the calculator turn that ratio into grams for the mug you actually own. Moving the same grinder from a French press to a cone is a grind size question; tap water you suspect is hard is a brew water one.
While it brews, and after
The timer is for hands that are busy with a kettle: large numbers, one step on screen at a time. Once the cup is poured, the journal keeps what happened on this device, and the dial-in guide reads two recorded brews and names a single change for the next one.
For a batch or a café drink
A jar that sits overnight belongs to the cold brew calculator, which also covers diluting a concentrate on the day. A drink built on a shot, from cortado to latte, belongs to the milk drink builder. The caffeine calculator starts from the grams of coffee used, so it can answer for a cup already drunk.
What none of them can do
None of these tools tastes your coffee. They do arithmetic on the figures you give them and say which of their own figures are assumptions, so a surprising result usually means a number was typed wrongly or a scale was not zeroed.