Coffee Is Dosed in Grams and Sold by the Ounce
Behind the bar everything is a gram: an 18 g dose, a 36 g shot, 60 g of ground coffee per litre of water. Walk two metres to the retail shelf and the same coffee is a 12 oz bag, and the green lot it came from was quoted per pound on an importer's price sheet. Somewhere between the roast log and the label, one number has to become the other.
Where the Two Systems Meet
The dose and the yield
The retail bag
The green lot
The roast batch
Checking a Dose, a Drop Weight or a Bag Fill
The routine is the same whether the number came off a brew scale, a roaster's drop bucket or a bag-filling machine.
Enter the gram figure
Type 18, 30, 340, 1000 — whatever the scale reads — into the left field. The ounce value updates as you type, and a comma is accepted as the decimal mark, so a readout noted down as 18,4 still works.
Compare it with the printed net weight
A bag that declares 12 oz needs at least 340.19 g inside it, so a fill target of 340 g sits right on the line and is usually set a gram or two higher.
Copy the plain number into the roast log
The copy button hands over the bare figure with no unit and no spaces, which is what a spreadsheet cell or a roasting-software field expects. Ctrl + C inside a field does the same.
Turn a bag size back into grams
Press the swap button (↔) to run oz → g when a US price list quotes 5 oz sample packs or a 32 oz tin. By hand, multiply by 28.349523125: 5 oz is 141.75 g.
Coffee Quantities from Single Dose to Wholesale Bag
The gram figures a café and a roastery handle every day, and the ounce value each one carries once it reaches a US label or price list.
| Coffee quantity | Where it turns up | Grams | Ounces |
|---|---|---|---|
| Espresso dose | Basket dialled in on the bar | 18 g | 0.6349 oz |
| Pour-over dose | 500 ml brew at roughly 1:16.7 | 30 g | 1.0582 oz |
| Batch-brew dose | One litre at the 60 g/L guideline | 60 g | 2.1164 oz |
| Small retail bag | Standard European shelf size | 250 g | 8.8185 oz |
| The “12 oz” bag | US specialty retail default | 340 g | 11.9931 oz |
| One-pound bag | US wholesale and subscription size | 453.59237 g | 16 oz exactly |
| Wholesale kilo bag | Roasted coffee delivered to a café | 1 000 g | 35.274 oz |
Notice how tight the margin is near the top of that shelf range. A 340 g fill is 11.9931 oz — 0.0069 oz short of the declared 12 oz — which is exactly why fillers are calibrated to overshoot slightly rather than land dead on the round number.
What Helps When You Are Weighing Coffee
Tenth-of-a-gram changes still show
Results carry up to eight decimals, so nudging a dose from 18.0 g to 18.3 g moves the ounce figure visibly instead of rounding it away.
Flip it to size a bag
One press reverses the direction — the one you want when a packaging spec arrives in ounces and the filling machine is set in grams.
Pounds and kilos for green coffee
Searchable dropdowns on both sides reach all eighteen weight units, so the same page copes with a 69 kg jute bag or a per-pound import price.
Figures that paste cleanly
Big values are shown with spaced thousands so they stay readable, while copying strips everything back to a plain number for your log.
Roasting and Dosing Questions
How much weight does coffee lose in the roaster, and which figure ends up on the bag?
Most of the loss is moisture driven out of the bean, with some dry matter burnt off as development continues. Light to medium specialty roasts usually shed 11–16% of the charge weight, and dark roasts go past 20%. The percentage is (charge − drop) ÷ charge, so 1 000 g of green dropped at 850 g is a 15% loss. The label always states the roasted net weight — that 850 g is 29.9829 oz, enough for two 12 oz bags with a little to spare.
Why is a 12 oz bag of coffee 340 g?
Because 12 oz works out at 340.194 g and 340 is the nearest tidy metric number. US packaging carries both a customary and a metric net-quantity statement, so the bag reads “12 oz (340 g)”. Taken literally, 340 g is 11.9931 oz — a whisker under the declared figure — one more reason the fill target is nudged above the nominal weight.
Is a volume scoop as repeatable as weighing the dose?
No, and the gap is wider than people expect. Bulk density shifts with roast level, origin, grind size and how the grounds settle, so a levelled two-tablespoon scoop that delivers 10 g of a dense light roast can deliver about 8 g of a puffed-up dark one. That is a fifth of the strength gone, from two scoops that look identical. Weighing removes the variable, which is why published recipes are written in grams.
How do brew ratios work when everything is weighed?
A ratio compares coffee mass with water mass, and water is convenient because a millilitre of it weighs about a gram. At 1:16, a 30 g dose takes 480 g of water; the familiar 60 g per litre guideline says the same thing per volume. Espresso applies the arithmetic to the output too — 18 g in and 36 g out is 1:2. Running the same sums in ounces would mean pairing 1.0582 oz with 16.93 oz for no gain.
Why do cafés weigh in grams when the packaging prints ounces?
The two numbers do different jobs. Brewing wants fine, easily divided steps: a gram is about 0.035 oz, so an ounce of coffee is roughly 28 gram-sized adjustments, and recipes turn on tenths of that. Retail labelling in the United States answers to the customary units shoppers recognise on a shelf. So the roastery works in grams from green intake to drop weight and converts once, at the moment the coffee gets a label.
No comments yet. Be the first to comment!