How much coffee should I use per cup?

Almost every complaint about home coffee comes back to the ratio, and almost nobody measures it. Once the ratio is fixed, the other variables become adjustable in a way they never are while the dose changes cup to cup.

Step by step

1. Learn one ratio and work from it.1 part coffee to 16 parts water by weight is the standard starting point for filter, cafetière, pour-over and drip. Everything else is a deliberate adjustment from there.
2. Convert it to your usual cup.Water is 1g per ml, so a 250ml mug takes about 15g of coffee. A 350ml mug takes about 22g. A one-litre cafetière takes about 60g.
3. Weigh rather than scoop.A tablespoon of coffee varies by grind size and how it is scooped, easily by half again. Cheap digital scales remove the single largest source of inconsistency in home brewing.
4. Know the tablespoon approximation.If you will not weigh, one slightly heaped tablespoon is roughly 7-8g of ground coffee. Two per mug. It is imprecise, and it is much better than a guess.
5. Treat espresso as a separate system.Espresso runs around 1 part coffee to 2 parts liquid — roughly 18g in for 36g out. Applying filter ratios to an espresso machine, or the reverse, produces something undrinkable.
6. Adjust strength with the ratio, not the brew time.Want it stronger, use more coffee. Brewing longer to compensate for too little coffee over-extracts what is there and makes it bitter rather than strong.
7. Understand strength against extraction.Strength is how much coffee is dissolved; extraction is how much you pulled from the grounds. Bitter usually means over-extracted — a coarser grind or shorter time — while weak-and-sour means under-extracted.
8. Change one thing at a time.Fix the ratio, then adjust grind size, then water temperature. Changing two together tells you nothing about which one helped.
9. Account for the water the grounds absorb.Coffee grounds retain roughly twice their own weight in water. Brewing 60g with a litre yields noticeably less than a litre in the cup, which matters when brewing to fill a specific pot.
10. Write down what works.Once a ratio, grind and time give a cup you like, note it. Reproducing it is the whole point, and it stops every morning being a fresh experiment.

Tips

• Scales with a timer are sold specifically for coffee and cost little, but any kitchen scale reading to 1g does the job.
• Fresher coffee tastes stronger at the same ratio, so a new bag may need a slight adjustment down rather than a change of method.
• If a cup is too strong for you, dilute it with hot water rather than under-dosing. That gives a weaker cup without the harsh flavours of a badly extracted one.

Common mistakes

• Brewing longer to make weak coffee stronger — It extracts more of the bitter compounds from the same amount of coffee. Strength comes from the ratio; brew time controls flavour balance.
• Measuring by scoop — Scoop volume varies with grind size and packing, so the dose changes between cups and nothing else can be judged reliably.

If it doesn't work

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