Ingredient Amount Converter

Ingredient conversion errors cause recipe failures. A cup of flour weighs 125 g, but a cup of honey weighs 340 g. Substituting weight for volume without accounting for ingredient density ρ produces incorrect ratios. This converter normalizes all volume units to mL and all mass units to g, then bridges the two domains using per-ingredient density values sourced from USDA SR28 food composition data. It covers 14 units across US customary and metric systems. Fraction output uses Unicode vulgar fractions for human-readable results matching recipe notation.

Limitations: density values assume standard ingredient packing. Sifted flour is less dense than scooped flour by roughly 15%. Brown sugar density assumes packed measurement per USDA convention. For high-precision baking, always prefer a kitchen scale. Pro tip: when converting between weight and volume for dry goods, the density value matters more than the conversion factor. A wrong density produces a mathematically correct but culinarily useless result.

All conversions follow a two-step normalization pipeline. First, the input amount is converted to a canonical base unit within its domain. Then, if the target unit is in the same domain, a single division yields the result. If the target is cross-domain (weight ↔ volume), the ingredient density bridges the gap.

For same-domain conversions (volume → volume or weight → weight), where factor_from is the multiplier to convert the source unit to the base (mL or g), and factor_to converts the base to the target unit.

For cross-domain conversion from volume to weight, where ρ is the ingredient density in g/mL. The inverse applies for weight to volume:

Where mass is in g and volume is in mL. The fraction formatting algorithm finds the closest fraction from the set {½, ⅓, ⅔, ¼, ¾, ⅛, ⅜, ⅝, ⅞} by minimizing |remainder − fraction| with a tolerance threshold of 0.05.