What does TDS mean in brewed coffee?

TDS in a brewed coffee is the percentage of the drink that is dissolved coffee rather than water. It measures strength, not quality.

Typical figures

• Filter coffee: 1.15 to 1.35 per cent is the widely used target band.
• Espresso: 8 to 12 per cent, which is why it is served in 30 ml rather than 300.
• Cold brew concentrate: often above 3 per cent before dilution.

Strength and extraction are different

This is the distinction that makes the numbers useful.

Extraction yield is how much of the coffee dissolved — controlled mainly by grind size and time.

TDS is how concentrated the result is — controlled mainly by the brew ratio.

You can brew a 1.5 per cent coffee that is under-extracted (lots of coffee, coarse grind) and a 1.1 per cent coffee that is perfectly extracted. They are independent axes, which is why the brewing control chart plots one against the other.

What to do with it

If your coffee tastes weak but pleasant, use more coffee — change the ratio.

If it tastes sour or bitter, change the grind — that is extraction, and adding coffee will not fix it.

Knowing which of the two you are complaining about is most of the battle.