ou have poured two cups from the same bag, and one came out too strong while the other tasted like water. Same coffee, same grinder, different result.
That difference is the brew ratio: how much coffee you used against how much water. It is the strength dial of the cup. Nothing else does that job.
Weigh both the next time. Start near 1:16, taste it, then you have a number to move from.
What the ratio actually is
The brew ratio is the weight of dry coffee against the weight of brew water. It is written as 1:N, where N is how many grams of water you use per gram of coffee. A 1:16 ratio means 16 grams of water for every gram of coffee, so 30 grams of coffee asks for 480 grams of water.
Weigh both numbers on a scale. Volume is unreliable, because a scoop of beans changes weight with roast level and bean size. Grams do not lie, and a ratio you can read off a scale is a ratio you can repeat tomorrow.
The range you will actually use
Most filter coffee lives between 1:15 and 1:17. That is roughly 60 grams of coffee per litre of water. A tighter ratio uses less water per gram of coffee, so the cup comes out stronger. A wider ratio uses more water, so the cup comes out lighter.
| Ratio | Coffee | Water | Result |
|---|---|---|---|
| 1:15 | 20 g | 300 g | Stronger, more concentrated |
| 1:16 | 20 g | 320 g | A balanced starting point |
| 1:17 | 20 g | 340 g | Lighter, more delicate |
Espresso sits far outside this range at about 1:2, near 18 grams of coffee to 36 grams in the cup. That is why a shot tastes intense next to a filter brew. It is a much tighter ratio, packing the same kind of flavor into far less water.
Strength is not extraction
The ratio sets strength, which is how much dissolved coffee ends up in the cup. It does not set extraction, which is how much flavor the water pulled out of the grounds. Those are two separate axes. Grind, temperature, and time move extraction. The ratio moves strength.
You can brew a strong cup that is under-extracted and sour, or a weak cup that is over-extracted and bitter, because the two dials turn independently. Widening the ratio thins out a cup without fixing a sour or bitter flavor. For that you adjust the grind. For the overall punch of the cup, you adjust the ratio.
Common questions
- What brew ratio should I start with?
- Start at 1:16 for filter coffee, which is 16 grams of water per gram of coffee. It sits in the middle of the common range and gives you a balanced cup to judge from. Move toward 1:15 if you want it stronger or 1:17 if you want it lighter.
- Does a tighter ratio fix sour or bitter coffee?
- No. Sour and bitter are extraction problems, and the ratio only changes strength. Adjust the grind for a sour or bitter cup, and use the ratio to make the whole cup stronger or weaker once the flavor is right.
- Why is espresso such a different ratio?
- Espresso runs near 1:2, far tighter than filter, so it concentrates a lot of flavor into very little water. That high concentration is what makes a shot taste intense next to a 1:16 filter brew.