What is the brewing control chart?

The brewing control chart plots two independent measures against each other, and its value is in showing that they are independent.

The axes

Vertical: strength (TDS) — how concentrated the drink is. Controlled mainly by the ratio.

Horizontal: extraction yield — how much of the coffee dissolved. Controlled mainly by grind size and time.

The target box sits around 1.15 to 1.35 per cent strength and 18 to 22 per cent extraction.

The nine regions

Outside the box, the chart names what you have:

• Weak and under-developed — too little coffee, too coarse.
• Strong and under-developed — plenty of coffee, too coarse. Tastes intense and sour.
• Weak and bitter — too little coffee, too fine.
• Ideal — the middle.

Why it matters practically

It makes clear that “my coffee is weak” and “my coffee is sour” are different complaints.

Weak means adjust the ratio: more coffee, less water.

Sour means adjust the grind: finer.

Doing the wrong one is the most common mistake in home brewing, and the chart is the clearest way to see why.

Using it without a refractometer

You cannot plot yourself on it without measuring. You can still use the framework: decide whether the problem is concentration or extraction, then change the matching variable.