Tool · cups per bag

Coffee bag calculator: how many cups in a bag?

A 12 oz bag makes about 26 eight-ounce cups at the Specialty Coffee Association’s 55 g-per-liter reference — 13 days at two cups a day. Enter your bag, cup, ratio and how much you drink to see doses, cups and days, and whether the bag is finished within the roughly three weeks the SCA treats as fresh for whole beans.

Updated 2026-11-04 · sources listed at the end · runs in your browser; nothing is stored or sent

Cups-per-bag calculator

Bag size

Water per cup

8 fl oz mug · 6 fl oz (NCA) · 5 fl oz coffeemaker “cup”

Ratio

55 g/L = SCA Golden Cup · 1 : N = N g of water per 1 g of coffee

Dose per cup, g (optional)

fill in to override cup × ratio (e.g. espresso)

Cups per day

Bag age when opened, days since roast date

Dose per cup13.0 g

Full cups per bag261.9 g left over

Days it lasts1326.0 g a day

Last cup, days after roast13

12 oz × 28.34952 = 340.2 g · 8 fl oz × 29.57353 = 236.6 mL ≈ 236.6 g water ÷ 18.18 = 13.0 g per cup · 340.2 ÷ 13.0 = 26 full cups · 26 ÷ 2 a day = 13 days

SCA: inside the window. The last cup comes about 13 days after roasting, within the roughly three weeks (21 days) the SCA treats as fresh for whole beans.

NCA: inside 1–3 weeks. The bag is open about 13 days; the NCA gives whole beans 1–3 weeks in an airtight container at room temperature.

At 26.0 g a day, the NCA’s “enough for one or two weeks” is 182–364 g (6.4–12.9 oz). Finishing within 21 days of roasting allows up to 547 g (19.3 oz); this bag is 206 g under that.

bag (g) = bag (oz) × 28.34952, or (lb) × 453.5924
dose (g) = water per cup (mL) ÷ N (1 mL of water ≈ 1 g; 55 g/L is N = 18.18)
full cups = bag (g) ÷ dose, rounded down
days = full cups ÷ cups per day
grams that fit the 3-week window = dose × cups per day × (21 − bag age)

The inputs, and where they come from

Input	Value used	Source
Ounce to grams	28.34952 g	NIST SP 811 (28.349 52 g); NIST’s quick table rounds it to 28.35
Pound to grams	453.5924 g	NIST SP 811 (0.453 592 4 kg)
Fluid ounce to mL	29.57353 mL	NIST SP 811; a US cup is 236.588 2 mL, so an 8 fl oz mug of water is 236.6 mL
Water, mL to g	1 mL ≈ 1 g	The gram was defined from a cubic centimeter of water, and water’s density stays very close to 1 g/cm³ (Wikipedia, Gram)
Default ratio	55 g/L = 1 : 18.18	SCA Golden Cup, 55 g/L ± 10%; SCA Standard 310-2021 tests home brewers at 55 g per 1.000 kg of water
Ratio presets	1 : 15 to 1 : 18	“Preferred brew ratios … often fall into the range of 15–18:1 by mass” (Wikipedia, Coffee preparation)
Freshness window	21 days from roast	SCA Coffee Decoded: whole beans “fresh” within about three weeks of roasting
Opened-bag range	1–3 weeks	NCA: whole beans in an airtight container at room temperature; 3–4 months frozen

The calculator works in grams of water in, not coffee out. Wikipedia’s cup article notes that a coffeemaker “cup” is 5 fl oz of water and usually yields about 4 fl oz of brewed coffee, because the grounds hold some back. If you measure by the mug you drink from, your water per cup is a little more than the mug holds.

Cups per bag: reference table

Full cups only, rounded down. Doses: 13.0 g per 8 fl oz at 55 g/L, 14.8 g at 1:16, 15.8 g at 1:15, and 8.1 g per 5 fl oz coffeemaker cup at 55 g/L.

Bag	Grams	8 fl oz, 55 g/L	8 fl oz, 1:16	8 fl oz, 1:15	5 fl oz, 55 g/L
8 oz	226.8	17	15	14	27
10 oz	283.5	21	19	17	34
12 oz	340.2	26	23	21	41
1 lb (16 oz)	453.6	34	30	28	55
2 lb	907.2	69	61	57	111
5 lb	2,268.0	174	153	143	278
250 g	250	19	16	15	30
500 g	500	38	33	31	61
1 kg	1,000	76	67	63	122

The SCA’s ±10% tolerance alone moves the count: a 12 oz bag gives 29 eight-ounce cups at 49.5 g/L (11.7 g each) and 23 at 60.5 g/L (14.3 g). Wikipedia’s summary of the 55–63 g/L standards gives about 14–16 g per 240 ml cup, the stronger end of this table.

How long a bag lasts

Days at 55 g/L with 8 fl oz cups. Shaded cells run past 21 days, so even a bag opened on its roast date would outlast the SCA’s roughly three weeks.

Bag	Cups	1 cup a day	2 a day	3 a day	4 a day
12 oz	26	26	13	8.7	6.5
1 lb	34	34	17	11.3	8.5
2 lb	69	69	34.5	23	17.3
1 kg	76	76	38	25.3	19

21 days after roasting — the SCA’s “about three weeks” for whole beans.
7–21 days after opening — the NCA’s 1–3 weeks for whole beans in an airtight container at room temperature.
Your bag, by roast date — from its age when opened to the last cup; moves with the calculator.
Your bag, by opening date — how many days it stays open; bars stop at 56 days with an arrow.

Drawn by pourxlab.com for this page from the SCA Coffee Decoded column and the NCA storage page (sources 9 and 10). Time axis to scale; the bars are calculated, not measured.

Reading the freshness result

The two checks count from different days. The SCA’s figure starts at roasting: its Coffee Decoded column says CO₂ degassing “occurs rapidly for the first 20 days after roasting” and that whole beans can reasonably be considered fresh “within about three weeks.” The NCA’s ranges describe storage once coffee sits in an airtight container: 1–3 weeks for whole beans at room temperature, 2 weeks refrigerated and 3–4 months frozen. So a bag that is already ten days past its roast date when you open it has 11 days left on the SCA count, however long the NCA range runs. Enter the age from the roast date on the bag; a best-by date alone does not tell you when the coffee was roasted (see coffee freshness).

An open bag may also go stale faster than a sealed one. Emma Sage’s 2012 SCAA review describes a “secondary shelf life” that begins once the consumer opens the package and “may occur at an accelerated rate,” a stage she notes has not been studied in detail.

If the bag outlasts the window, the calculator shows by how many grams. The NCA’s own advice is to “buy smaller batches more frequently—enough for one or two weeks,” and, for coffee kept in the freezer, to use a truly airtight container and take out no more than a week’s worth at a time. Weekly portioning is laid out step by step on the how to store coffee beans page.

Why your count may come out lower

Scoops instead of grams. The NCA’s “1 to 2 tablespoons of ground coffee for every 6 ounces of water” spans a factor of two, so the same bag gives very different cup counts by the spoon. Weigh once, or convert with the tablespoon-to-grams converter.
Bigger cups than you think. A 12 fl oz mug needs half again as much coffee as an 8 fl oz cup. Weigh the water you actually brew with (1 mL ≈ 1 g).
Stronger ratios. Moving from 55 g/L to 1:15 costs a 12 oz bag five cups (26 to 21).
Dialing in. Test brews while you adjust the grind come out of the same bag; subtract them from the total.

Common questions

How many cups are in a 12 oz bag of coffee?

About 26 eight-ounce cups at 55 g/L, 23 at 1:16 and 21 at 1:15 — or 41 coffeemaker “cups” of 5 fl oz at 55 g/L.

How many cups in a pound of coffee?

A pound is 453.6 g: 34 eight-ounce cups at 55 g/L, 30 at 1:16, or 55 coffeemaker cups.

How much coffee do I need per week?

Dose × cups per day × 7. At 13.0 g and two cups a day that is 182 g (6.4 oz). For per-cup amounts by machine and mug size, see how much coffee per cup; for any other brew size use the coffee-to-water ratio calculator.

The result is arithmetic, not a test of your coffee. Freshness figures come from sources measuring different things — lab degassing for the SCA, practical storage ranges for the NCA — so read them as a guide to how much to buy at once, not as an expiry date.