For a big batch, keep the same 1:16 ratio you would use for one mug: about 63g of coffee per litre of water, or 17g for every 8-ounce cup you want to pour. For a crowd, plan on about 1½ cups per guest at a morning event and 1 per guest after dinner, then read your amounts off the chart below.
A ratio does not change with batch size, so the arithmetic is the easy part. What goes wrong with big batches is everything around it: running out, coffee cooking on a warming plate, and a full basket that brews stronger than a half-empty one. This guide covers those too.
How much coffee for each party size
These amounts give you that many full 8-ounce cups in the pot, after the grounds have soaked up their share of the water. That is why they work out a little higher than the 15g per cup in how much coffee per cup, which counts the water going in.
| 8-oz cups | Water | Coffee | Tbsp | Cups of ground coffee |
|---|---|---|---|---|
| 4 | 1.1L | 68g | 14 | A scant 1 |
| 8 | 2.2L | 135g | 27 | 1¾ |
| 12 | 3.3L | 203g | 41 | 2½ |
| 20 | 5.4L | 339g | 68 | 4¼ |
| 30 | 8.1L | 508g | 102 | 6⅓ |
| 50 | 13.5L | 846g | 169 | 10½ |
Tablespoons are level, at about 5g each; a cup of ground coffee is 16 tablespoons, or about 80g. Spoons drift with grind and roast, so for anything over a few cups a kitchen scale saves real coffee and guesswork.
For a stronger pot, go to 1:15 by adding about 7% more coffee. For a lighter one, 1:17 is about 6% less.
How many cups per guest
These are rules of thumb, not data. Adjust them for people you know.
- Breakfast, brunch, or a morning meeting: 1½ cups each. Coffee is the point.
- After dinner: 1 cup each, and fewer takers than you expect if it is late.
- An all-day event: 1 cup each per two to three hours.
- Coffee-heavy crowd: add half a cup each, and have decaf on hand.
So a brunch for 20 people is 30 cups: about 8 litres of water and 510g of coffee, just over a 1-pound bag.
How much coffee to buy
At this rate, which counts only coffee you actually pour:
- A 12-ounce bag (340g) makes about 20 cups.
- A 1-pound bag (454g) makes about 27 cups.
- A 2-pound bag (907g) makes about 54 cups.
Buy a little over what the chart says. Running out halfway through is worse than having leftover beans, which keep for a few weeks; see how long coffee stays fresh.
Which brewer for a crowd
A drip machine is the easiest choice for up to about 30 people. A 12-cup machine holds about 60 to 72 ounces of water, roughly 1.8 to 2.1 litres, which takes 110 to 130g of coffee and pours about seven 8-ounce cups. For more, brew back to back into thermal carafes. The drip method page covers the rest of the recipe.
Watch the basket. A full dose of coffee nearly fills it, and if the wet grounds reach the top of the filter it can overflow. If yours is that close, brew two smaller pots instead.
Several French presses work for a smaller group and need no power beyond a kettle. A 1.5-litre press takes 80g of coffee and 1280g of water and pours four to five mugs; see the French press sizing table.
A coffee urn is the tool for 50 or more. Follow the chart in its manual rather than this one: most urns percolate, cycling the water through the grounds again and again, so they extract more from each gram and call for less coffee per cup than a drip machine. Start it well before guests arrive, since a full urn can take close to an hour.
Cold brew is the make-ahead option for a warm-weather crowd. Brew a concentrate up to a few days ahead, and dilute it by the jug on the day. The cold brew ratio shows how much coffee that takes. For iced coffee made fresh, see how to make iced coffee.
Pourover is the wrong tool here. A large cone tops out around 45g of coffee and 21 ounces, and each one needs you standing over it.
A full basket brews stronger
The ratio holds at every size, but the extraction does not. A full basket makes a deep bed of coffee, and water takes longer to work through it, so it pulls more out. Brewed at the same grind as a small pot, a full one can taste heavy or bitter.
The fix is the grind, not the dose: grind a step coarser for a full pot. If you cut the coffee instead, you get a cup that is both weaker and still over-extracted. The drip guide’s batch section explains the same thing from the small-batch side.
If you are buying pre-ground coffee for the day, a drip grind is right for drip machines and urns. Grind no more than a day ahead and keep it sealed.
Keeping a big batch hot
Coffee left on a warming plate keeps cooking. Within about half an hour it tastes stewed and bitter, however well it was brewed.
- Pour it into a thermal carafe or pump pot as soon as it finishes. Preheat it with hot tap water first, so the coffee does not lose its heat to cold steel.
- Drink it within about an hour for the best flavour. A good thermal carafe keeps it hot for a few hours, but the aroma fades long before the heat does.
- Brew in rounds for a long event, rather than one huge batch at the start.
- Never reheat it to boiling. It tastes burnt and sharp. Brew a fresh pot instead.
Use the calculator for other amounts
The ratio calculator opens on drip at 1:16. Enter the water your machine or urn holds, and it gives you the coffee and how much you will actually pour. It takes up to 5 litres at a time; for more, work out one batch and multiply.