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Coffee servings calculator
Put your guests, cups each, grams per cup and bag size in: 12 guests at 2 cups each need 24 cups — 360 g of coffee at 15 g a cup, 5.76 L of water, 2 bags at 340 g a bag.
★ FOOD · DRINKS · COFFEE
Coffee Servings Calculator: 360 g for 12 Guests, 24 Cups
On the defaults — 12 guests, 2 cups each, 15 g a cup, 340 g bags — you need 360 g of coffee for 24 cups, bought as 2 bags. This is the coffee servings tool: count the guests once, weigh the coffee once, and brew enough for the whole party — a pot that runs dry mid-morning waits for no second bag.
What does coffee needed 360 g for 24 cups mean?
It means 12 guests drinking 2 cups each need 24 cups of coffee, brewed from 360 g of ground coffee with 5.76 litres of water, bought as 2 bags of 340 g. The cups are the guests times the cups each, the coffee is the cups times the grams per cup, the water is the cups times 240 ml a cup, and the bags are the coffee divided by the bag size, rounded up — because coffee is sold by the bag, not by the gram. The second bag is barely opened on the day: 360 g against two 340 g bags leaves 320 g in the second bag, which is the next morning coffee, not waste.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Cups | guests × cups each | 24 cups — 12 × 2. |
| Coffee | cups × grams a cup | 360 g — 24 × 15. |
| Water | cups × 240 ml | 5.76 L — 24 × 240 ml. |
| Bags | coffee ÷ bag size, rounded up | 2 bags — 360 ÷ 340, rounded up. |
Three things to check before you trust the number
First, judge the cups each honestly: a brunch crowd at 3 cups each needs 540 g for the same 12 guests, while a dinner party at 1 cup each needs only 180 g, so the occasion moves the order more than the guest count does. Second, weigh the coffee, do not scoop it: a gram scale beats a scoop, since grind size changes what a scoop holds. Third, remember the water is 240 ml a cup — a small cup at 180 ml uses less water but the same coffee if the grams per cup stay fixed. For the ratio behind the grams, the coffee to water ratio chart compares brew methods side by side.
Worked example
12 guests, 2 cups each, 15 g a cup, 340 g bags. Cups: 12 × 2 = 24 cups. Coffee: 24 × 15 = 360 g. Water: 24 × 240 ml = 5760 ml = 5.76 L. Bags: 360 ÷ 340 = 1.06, rounded up to 2 bags. In practice that means buying 2 bags, opening both, and keeping 320 g of the second bag for the next morning — the party coffee is 360 g, and the leftover is not a shortage.
Every branch, checked
With 16 guests instead of 12, the cups rise to 32 and the coffee to 480 g, still 2 bags. With 3 cups each, the cups rise to 36 and the coffee to 540 g, still 2 bags, since 540 g against 340 g bags is 1.59, rounded up to 2. With 18 g a cup, the cups stay 24 but the coffee rises to 432 g, still 2 bags. With 500 g bags, the coffee stays 360 g but the bags fall to 1, since one 500 g bag covers the whole party. Guests, cups each, grams a cup and bag size each move the order on their own, so a wrong cups-each figure is as costly as a wrong guest count.
The reverses, worked backwards
The guests behind 360 g are 12: at 8 guests the need is 240 g for 16 cups (8 guests, 2 cups each, 15 g a cup, 3.84 L water, 340 g bags, 1 bag); at 16 guests it is 480 g for 32 cups (16 guests, 2 cups each, 15 g a cup, 7.68 L water, 340 g bags, 2 bags). The cups each behind 360 g are 2: at 1 cup each the need is 180 g for 12 cups (12 guests, 1 cup each, 15 g a cup, 2.88 L water, 340 g bags, 1 bag); at 3 cups each it is 540 g for 36 cups (12 guests, 3 cups each, 15 g a cup, 8.64 L water, 340 g bags, 2 bags). The grams a cup behind 360 g are 15 g: at 10 g the need is 240 g for 24 cups (12 guests, 2 cups each, 10 g a cup, 5.76 L water, 340 g bags, 1 bag); at 20 g it is 480 g for 24 cups (12 guests, 2 cups each, 20 g a cup, 5.76 L water, 340 g bags, 2 bags). Each reverse moves one input and holds the rest, so the step is exactly one guest, cup or gram change.
What the defaults assume
The defaults assume 12 guests, 2 cups each, 15 g of coffee per cup, 240 ml of water per cup, and 340 g bags. They do not assume milk, sugar, decaf or a second brew method — a party with espresso drinkers brews them separately, and the water figure is for filter-style cups, not espresso shots.
Who uses this
- A host planning a brunch: the 360 g order settles the coffee run before the guests arrive.
- A caterer costing a morning event: the grams per guest, times the guest count, give the coffee line on the quote.
- An office manager stocking a meeting: the bag count off the calculator is the order, not a guess at the shelf.
- A home brewer scaling a recipe: the same maths on one guest gives the grams for a quiet morning pot.
Accuracy & limitations
The arithmetic is exact for the inputs entered; the judgement is the cups each and the grams per cup. Real parties drink unevenly — early guests drink more, late guests drink less — and the scale overrides any planning figure; a cups-each figure guessed one cup low under-brews by 180 g on this party, and a grams figure read off a different brew method over- or under-extracts. Treat 360 g as the planning order for 12 guests at 2 cups each and 15 g a cup, and keep one spare bag for a crowd that stays for a third cup.
Cite this calculator
Bright Side Kit, “Coffee Servings Calculator: 360 g for 12 Guests, 24 Cups”, https://brightoolbox.com/coffee-servings-calculator/, accessed 3 November 2026. Students and researchers: cite the calculator name, the page URL and the date you used it, and quote the defaults (12 guests, 2 cups each, 15 g a cup, 340 g bags) so the 360 g result can be checked.
Frequently asked questions
How much coffee do I need for 12 guests?
360 g for 24 cups at 2 cups each and 15 g a cup, with 5.76 L of water, bought as 2 bags at 340 g a bag.
How do I work out coffee servings from a guest count?
Multiply guests by cups each for cups, multiply cups by grams per cup for coffee, and divide by the bag size, rounded up, for bags. 12 guests at 2 cups each and 15 g a cup is 24 cups, 360 g, 2 bags.
How much water do I need for 24 cups of coffee?
5.76 litres, at 240 ml a cup. The water follows the cups, not the coffee weight — a stronger brew uses the same water with more grams.
How many bags of coffee should I buy?
Divide the coffee by the bag size and round up: 360 g against 340 g bags is 1.06, so 2 bags. The leftover 320 g of the second bag is the next morning coffee.
Does a bigger bag mean less coffee?
No — bag size changes only the bag count. The same party needs 360 g whether the bags hold 340 g or 500 g; only the count falls, from 2 bags to 1.
What if guests drink 3 cups each instead of 2?
The coffee rises to 540 g for 36 cups, with 8.64 L of water, still 2 bags at 340 g. The coffee to water ratio chart checks the brew strength either way.