Batch Cooking Calculator

Because evaporation happens at the surface and the surface did not change. Twice the liquid in the same pan is twice as deep, so steam leaves at the same rate but has twice as much liquid to leave from — the reduction per unit of food is halved. Triple the recipe and it is a third. Splitting the batch across two or three pans restores the original surface-to-volume ratio and the original timing.

Almost never, and the reason is geometry. For stews, soups and braises the time is set by how long the ingredients need to soften, which barely changes with quantity — add perhaps 10–20% for the larger mass coming up to temperature. For roasts the time depends on thickness rather than total weight, so a bigger joint takes longer but two joints of the same size do not. Only reduction time genuinely scales, and that is a surface problem rather than a time problem.

More than people expect, because the fixed costs dominate. With 25 minutes of setup and cleanup plus 4 minutes of prep per portion, one portion takes 29 minutes and eight take 57 — eight times the food for 1.97 times the time. Per portion that is 29 minutes falling to just over 7. The saving comes almost entirely from paying the setup, preheat and washing-up cost once instead of eight times.

For boiling and simmering, yes. For anything that needs to reduce or brown, only if the bigger pan is genuinely wider rather than deeper. What matters is surface area, not volume: a tall stockpot holding twice as much with the same diameter gives you no extra evaporation at all. A wide shallow pan of the same capacity gives you a great deal.

Aim for a single layer covering no more than about 70% of the surface, with visible gaps between pieces. Crowding traps moisture, the food sits in its own liquid, the surface temperature is pinned near boiling and browning stops. The visual test is simple: if liquid pools in the pan rather than evaporating on contact, it is too crowded and you are steaming rather than roasting.

Yes, roughly 15% longer for the second tray. Each tray absorbs heat and obstructs airflow, so the oven recovers more slowly and the air circulates less. Rotate the trays halfway through, swapping shelves and turning them front to back, because no domestic oven is even enough to skip it. Even with the penalty, two trays at once is far faster than two sequential rounds.

Salt roughly follows the quantity. Aromatics, chilli, garlic and strong spices should be scaled to around three quarters and adjusted at the end, because they concentrate during a long cook and a large batch usually cooks longer. The full treatment of what does and does not scale — including leaveners and whole eggs, which are the two real traps in baking — belongs to the recipe scaling calculator.

This is the genuine safety limit on batch size. A large pot retains heat for hours and can sit in the bacterial danger zone the whole time. Divide hot food into shallow containers no more than about two inches deep before refrigerating, rather than putting the whole pot away. The USDA guidance is to get food from 140°F to 70°F within two hours and down to 40°F within four more.

Batching wins decisively on time and cost, and loses on texture and variety. Dishes that improve or hold well — stews, braises, soups, grains, roasted vegetables, sauces — are worth batching. Anything that depends on a crisp surface or a just-cooked texture is not. A common compromise is batching the components rather than the finished dishes: cook grains, proteins and sauces separately and assemble fresh.

Large enough that the fixed setup cost is spread thin, small enough that it fits your pans and gets eaten before it turns. Eight to twelve portions is the usual sweet spot for a household: the per-portion time has already fallen most of the way toward its floor, and the food still fits in normal equipment. Beyond that, the gains get smaller while the pan count and cooling problem keep growing.