Three different numbers, all called yield
Curd off the vat, wheel off the press, wheel out of the cave. Each weighs less than the one before it, and a yield figure that does not say which one it means is not usable. The page asks you which stage you measured at because the difference is not small: on the figures in the form — 100 gallons at 8.6 lb a gallon, a ten percent green yield and eight percent lost in the cave — the wheel off the press is 86 lb and the wheel that gets sold is 79.12 lb. Somebody quoting ten percent while weighing aged wheels is running a green yield near 10.9 percent, and would fill their vat differently.
Nothing about that is exotic. It is the same trap as a hanging weight against a cut weight in a butchery, and it catches people the same way.
The chain does not commute
Run the default vat forward: 860 lb of milk, ten percent green, 86 lb off the press, eight percent gone in the cave, 79.12 lb ready to sell. At 9 lb a wheel that is eight wheels with 7.12 lb over — enough that most makers hoop a ninth short one rather than eat it.
Now run it backwards from eight wheels. Seventy-two pounds finished, divided by 0.92 for the cave loss gives 78.26 lb green, divided by 0.10 gives 782.61 lb of milk, which is 91 gallons. Put 91 gallons in and you get exactly your eight wheels and nothing over. The page runs the answer forward again and prints the result, because a yield chain with a loss on each end is easy to get inside out, and a chain that does not close is a chain with a mistake in it.
Milk in a pound, and why the last point is the expensive one
At 28 dollars a hundredweight the milk costs 28 cents a pound, and a finished pound of cheese at this yield carries 10.87 lb of milk, so the milk in a pound is 3.04 dollars. Push the green yield from ten percent to eleven and the same pound carries 9.88 lb of milk and costs 2.77 — a saving of 27 cents a pound, about 21 dollars on this vat.
Try the same point again from eleven to twelve and it is worth less, because milk per pound goes as one over the yield rather than down a straight line. The first point you find is the cheapest one you will ever find, and every one after it costs more work for less money. That is worth knowing before anybody spends a winter chasing half a point.
Where the number moves without you touching anything
Fat and protein. Spring milk and late-lactation milk from the same animals do not behave the same in the vat, and a herd that changes feed in June shows up in the yield in June. Makers who keep one annual yield figure are averaging over a swing they could be planning around, and the fix costs nothing: write the vat volume and the pressed weight on a sheet every make day. After a season the page has a real number to work with instead of a placeholder.
The other half of the honest answer is what is not in here at all. Curd fines going out with the whey, fat left in the whey, a wheel pressed wetter than last week, a cave that ran humid in August — every one of those lands inside the yield you measured, which is precisely why it is a field and not a constant.
Questions people ask
How many gallons of milk make a pound of cheese?
On the figures in the form, 1.26 gallons of milk per finished pound — 10.87 lb of milk at 8.6 lb a gallon. But that answer is entirely a function of the yield you enter and the aging loss you enter, and both are things you measure on your own wheels rather than look up. A different milk, a different make and a different cave give a different number, and the point of the page is to work it from yours rather than to publish one.
What is the difference between a green yield and an aged yield?
Green is the wheel weighed coming off the press, still full of the water it will lose. Aged is the same wheel weighed when it is ready to sell. On the default figures those are 86 lb and 79.12 lb out of the same vat, so a yield quoted without saying which stage it means can be eight percent wrong before you start. The page has a selector for it because that is where most of the confusion between two makers comes from.
How much weight does a wheel lose while it ages?
Weigh one and find out — there is no general figure, and this page will not offer one. A wheel with a dry natural rind in a room held low in humidity loses a great deal over months, and a waxed or vacuum-bagged wheel loses very little because the water has nowhere to go. The rind treatment, the room and the length of the aging all matter, so the loss is a field on the form that you fill from your own before-and-after weights.
How much milk do I need for a specific number of wheels?
Enter the wheel count in the form and read the backwards block. It divides by the aging loss first and then by the yield, in that order, because doing it the other way round gives a different and wrong answer. Eight nine-pound wheels at the default figures need 91 gallons. The page then runs that number forward again and prints what comes out, so you can see the chain closes rather than trusting it.
Does this tell me whether my cheese is safe or legal to sell?
No, and it cannot. This page only moves weights around a chain you defined. Pasteurisation, raw-milk rules, minimum aging periods, licensing, testing, labelling and who you may sell to are set by the authority over your dairy, differ by country, state and county, and change. Raw-milk cheese is regulated particularly tightly and the rules are not the same in any two places. Ask your dairy regulator and your inspector.