How BatchLadle calculates

Units and ingredient conversions

Conversions within a physical quantity use unit relationships. Grams to kilograms is a mass conversion; millilitres to a defined cup is a volume conversion. Moving between mass and volume requires an ingredient-specific relationship.

For a reference with a defined physical volume, density for this calculation is reference mass divided by reference volume. Estimated mass is requested volume multiplied by that density. Estimated volume is requested mass divided by density. Keep the ingredient state and source attached to both directions.

A source measure without an established millilitre definition remains a source measure. It can scale within the source’s stated relationship. It cannot establish a physical density merely because the unit is called a cup.

Which unit definitions are used

The US customary cup is 236.5882365 mL under the exact unit relationships used here. BatchLadle’s metric kitchen choices are 250 mL per cup, 15 mL per tablespoon, and 5 mL per teaspoon. These settings do not override a recipe author’s explicit definition.

NIST’s separate cooking-equivalencies page uses approximate kitchen values, including a 240 mL cup. Those approximations are documented as such and are not substituted for the exact US customary definitions.

A publisher’s measure can differ from these tool settings. Women’s Weekly Food specifies a 20 mL tablespoon; Doves Farm defines a 240 mL cup. Preserve those explicit source measures when interpreting references rather than relabeling them as the tool’s standard units.

Serving changes

The serving factor is target servings divided by original servings. Each supported numeric ingredient amount is multiplied by that factor. Original servings must be greater than zero, and the target must be positive and within the tool’s supported range.

The calculation always starts from the original values. Display rounding is applied to the result, not reused as the next calculation’s input. Nonnumeric instructions remain notes, and ambiguous ranges need review. Cooking times are not multiplied by the serving factor.

When one ingredient determines the batch, its available amount divided by its original amount gives the factor. Both must use the same original unit and preparation. Target servings are original servings multiplied by that factor. This applies one selected limit; it does not check other ingredients or optimize a pantry.

Baker’s percentages and starter

Total flour is the 100% basis. Each ingredient percentage is ingredient mass divided by total flour mass, multiplied by 100. All identified flour contributions belong in the basis, including flour in a starter.

For starter mass S and hydration H expressed as a percentage, starter flour is S × 100 ÷ (100 + H), and starter water is S × H ÷ (100 + H). These two parts sum to the starter mass. Add them to the flour and water totals for percentage calculations, but count the starter only once when summing the added dough ingredients.

Hydration uses identified water plus declared starter water. It does not count the entire mass of mixed ingredients such as milk or honey as water. A target dough weight scales all added ingredient masses by target weight divided by original dough weight.

Pan geometry

A round straight-sided model has base area π × (diameter ÷ 2)². A square has side²; a rectangle has length × width. Modeled volume is base area × chosen fill depth × pan count.

The target-to-original volume ratio supplies the comparison factor. At equal fill depth, the common depth cancels and the area ratio is sufficient. Internal dimensions, tapering, and irregular shapes affect how well the model describes a real pan. The result does not predict rise, safe fill, or cooking time.

Shopping-list grouping

Grouping uses ingredient identity, state, preparation text, and the original unit dimension. Mass amounts are normalized to grams and defined volumes to millilitres. Source-measure groups also preserve the selected reference. A displayed result unit does not change the original grouping basis.

The shopping list does not automatically use density to merge mass with volume. Unmatched manual rows stay separate until an appropriate directory identity is assigned in the recipe. Unresolved lines remain visible, and a shopping purchase size remains a practical decision separate from the recipe quantity.

Precision, checks, and changes

Keep the source’s original relationship, preparation state, and review date with an ingredient reference. A check date records inspection of the source; it is not a laboratory validation date.

Approximate ingredient estimates remain approximate even when the arithmetic contains many digits. If a source changes or a data issue is found, review the affected reference and its dependent pages. Keep a saved recipe’s source selection understandable when revisiting an older calculation.