The shot count everybody quotes is wrong
Five pounds is 2,268 grams. At an eighteen gram dose that is 126 baskets, and 52 dollars over 126 baskets is 41 cents. Every number in that sentence is right and the conclusion is wrong, because 126 baskets never happen.
Twenty grams get purged when the hopper is swapped. Half a percent of the bag — eleven grams — goes on the bench, into re-weighed doses and into baskets that got knocked. That leaves 2,237 grams, which is 124 whole baskets. Three of those go in the bin while the grind is found. A hundred and twenty-one reach a cup, and 52 dollars over 121 is 43 cents.
Two cents. On 180 drinks a day, seven days, that is 25 dollars a week that was not in the spreadsheet.
Why bag size changes the answer
The dial-in cost is fixed per bag and the baskets are proportional to it, so the penalty is a percentage that moves with bag size. Three binned baskets out of 124 is 2.4 percent. Three out of a twelve ounce bag, which makes about seventeen baskets after the purge, is nearly eighteen percent — and the purge itself is six percent of that bag rather than under one percent.
That is not an argument for buying the biggest bag available. Coffee sitting open in a hopper has its own cost and it does not show up on any invoice. It is an argument for knowing which of the two you are paying, because most bars are paying one of them without having chosen.
Retention is not waste
Grinders hold grounds between doses and it is tempting to count that as loss. It is not. What stays behind on one dose comes out on the next, so the same grams get counted twice if you subtract them every time. Only the grams that actually leave — the purge when the coffee changes, the spillage, the binned baskets — are gone. That distinction is why the retention figure on this form is asked for once, at a bag change, and not per shot.
What this deliberately leaves out
Milk, cups, lids, sleeves and syrup are one field with your number in it, because they are a different calculation with different waste in it — milk in particular gets pulled by the pitcher and poured by the cup, and the gap between those two is not small. Labour is not here at all, and neither is the machine, the water treatment or the card fee. What is here is the coffee, worked out honestly, which is the part most often worked out carelessly.
Questions people ask
How much does a shot of espresso cost a cafe?
With a five pound bag at 52 dollars and an eighteen gram dose, 43 cents a basket once the hopper purge, the spillage and three dial-in baskets are taken off — against 41 cents if you just divide the bag weight by the dose. Your own answer moves with your bag price, your dose and above all with how often you change coffee, since the dial-in cost is charged per bag rather than per shot.
How many shots are in a bag of coffee?
Fewer than the weight suggests. Divide the bag by the dose and you get the baskets the coffee could make; then take off what is purged when the hopper changes, what gets spilled, and the baskets binned dialling in. With the defaults here that is 126 on paper and 121 in cups. On a twelve ounce bag the same subtractions take a much larger share.
Does grinder retention cost me coffee?
Not per shot, and counting it that way double-counts. Grounds held between doses come back out on the following dose. What is actually lost is the retained coffee that gets purged when you change to a different bag, which is why the page asks for it once per bag change rather than per basket.
Why is dial-in more expensive on small bags?
Because it is a fixed cost per bag spread over however many baskets the bag makes. Three binned baskets is 2.4 percent of a five pound bag and close to eighteen percent of a twelve ounce one. The purge behaves the same way. Both effects are why a bar that changes coffee often pays materially more per shot than one that does not.
Should I buy bigger bags to cut the waste?
The arithmetic on this page says yes and the arithmetic on this page is not the whole question. A larger bag spreads the purge and the dial-in over more shots, and it also means coffee sitting open for longer, which costs you something the invoice never shows. Work out the per-shot saving here, then decide against how fast you actually get through it.