Tool
Batch-brew calculator
Coffee and water for however many cups you need, with a capacity check so the answer is one your brewer can actually make.
For this batch
120 g coffee · 1920 ml water
120 g of coffee for 1920 ml of water is a ratio of 1:16, in the middle of the usual range. The grounds keep some of the water, so slightly less than 1920 ml reaches the pot.
- If it tastes different from the original
- If the batch tastes weak, lower the ratio number a step, which uses more coffee for the same water. If it tastes bitter or drains slowly, keep the ratio and grind a little coarser: large batches hold the water in the bed for longer.
- Keep the same
- The coffee and the grind while you settle the ratio, then the ratio while you adjust the grind. Changing both at once makes the result unreadable.
- What this cannot tell you
- The arithmetic is exact. Whether the result tastes like the original is not: extraction shifts with batch size, bed depth and the shape of the brewer, and this tool cannot predict by how much.
Exact arithmetic on your numbers
What to do with the result
- You want the machine's own page: how it brews and where to start: Batch brewer
- The pot is brewed and tastes wrong: Make my coffee better: batch brewer
- You are scaling a recipe written for one cup: Brew recipe scaler
How it works
Cups multiplied by cup size gives the water; water divided by the ratio gives the coffee. The capacity check then compares the total against the brewer range you enter.
What the inputs mean
- Cup size
- How much finished coffee one person gets. Mugs are commonly 250-350 ml; a small cup is nearer 150 ml.
Worked examples
Filter coffee for four at breakfast
- 4 cups
- 250 ml per cup
- Ratio 1:16.7
Result: 1,000 g of water and 60 g of coffee.
Common mistakes
Forgetting that the grounds keep some of the water
A 1,000 g brew yields noticeably less than a litre in the pot. Add a little extra water if the finished volume matters.
Using the same grind as for a single cup
A deeper bed drains more slowly. Larger batches usually want a slightly coarser grind.
What the result does not mean
- Fitting inside the brewer's capacity does not mean the brewer will extract evenly at that size.
What this does not account for
- Uses a linear ratio scaled by cup count — does not model how larger coffee beds can extract slightly differently from single-cup brews.
- Ignores the water the grounds retain, which is roughly twice their own weight and comes off the finished volume rather than the brew water.
- The capacity check compares against a general brewer capacity range you enter, not a specific product's exact limit.