Scaling rules

Double the batch, double everything? Not always. Xanthan gum, starter cultures, anything dosed per jar: some lines refuse to scale linearly. In BatchDash each recipe line carries its own scale rule. Open it from the line’s Scale rule action; the dialog asks how the line should follow the batch and shows an “At a glance” preview of the result.

The four rules

Rule	Behavior	Example
Scales with the batch	The default. Keeps its percentage share at any size.	Habaneros stay 62% at 2 kg or at 40 kg.
Fixed amount	The same dose whatever the batch size.	40 g of xanthan gum per batch.
Per started slice	An amount per every started slice of output, rounded up.	1 sachet of culture per every started 20 L; a 25 L batch takes 2.
Per portion	Counted from the batch’s portions. Needs a portion size on the recipe.	0.25 g of vitamin C per 250 ml jar.

Weigh-ins versus rules

On the bench you might weigh 43 g of gum into a trial batch. The weigh-in records what happened that day; the rule decides what the line does when the batch is resized. The recipe keeps the share you weighed, so setting a rule never restates the batch you already made, and the yield goes on reading what the process really lost. Cost is the exception: a rule line is priced by its rule at the recipe’s own batch size, because a rule is not linear and one cost per unit has to be quoted at some size.

Under the preview the dialog notes what you weighed. If the rule asks for a different amount at that same batch, it says so in amber. The two readings disagree and no arithmetic can settle which one you meant, so check the slice, the portion size, or the finished mass you recorded.

Two ways to read a slice

“One crust per 900 g” reads two ways, and they give different answers. Is that 900 g of filling, or 900 g of finished quiche? A 950 g quiche is one crust plus 720 g of filling on the first reading. On the second it is two crusts.

Count the slice without this ingredient says which you meant. Off (the default, and what every rule written before the switch means) the slice counts the whole finished batch. On, each slice covers its own dose too: one crust per 900 g of filling works out as one crust per 1130 g of quiche.

When the ingredient is the container

A sachet of culture and a pie crust both round up, for different reasons. Half a sachet is wasted and the batch is still whatever size you like. A crust holds 8 portions, so a 10-portion batch does not exist: you would buy two crusts and filling for ten, and the second one comes out nearly empty.

This ingredient sets the batch size says the line is a container. Every batch is then a whole number of them, and the run form says so while you are still typing the target:

10 portions is 1.25 batches. Whole batches either side: 8 portions · 16 portions

Click either figure and it becomes the target. Nothing is blocked, because sometimes you really do bake a small odd one in a different tin, and the run page keeps saying what that batch is. One line per recipe can set the batch size. Two containers of 8 and 12 portions would only agree at 24, which is a worse sum to work out on a form than a plain refusal to set the second.

Where rules matter

Rules apply everywhere a batch changes size:

• On the recipe sheet, when you rescale to a target quantity or a portion count.
• When planning a run, where the exploded ingredient list respects each rule before stock is checked.

Wherever a rule applies, its amount comes out of the batch first and the rest of the recipe divides what is left. A 10 kg batch with a 3 g vanilla pod is 3 g of pod and 9 997 g of everything else, so the batch weighs the 10 kg you asked for.

Set the rule once and the 40 kg sheet stops telling you to add 800 g of xanthan gum. A side effect worth knowing: fixed and stepped lines change the cost per unit as batch size moves, since their cost spreads over more or less output. The cost panel follows along; see cost breakdown and yield and batch size.