Recipe portion scaler

Non-positive servings or amounts, empty lists, and non-finite values are rejected with invalid_input so bad data never produces a silent zero batch.

How to call the API: fields, validation, and the response shape

Each amount must likewise be positive and finite; an empty list is rejected because there is nothing to scale. Prefer putting units in the optional names field rather than inside amount strings so two hundred fifty and flour in grams stay separate and the solver never has to parse mixed text. Send a JSON body with amounts as a required array of finite positive numbers—or a comma-separated string on text forms—plus original_servings and target_servings (aliases include servings, from_servings, original for the source count, and target, to_servings, new_servings for the destination). Both serving counts must be strictly positive finite numbers; zero, negative, missing, or non-numeric values return invalid_input and are never charged. Absolute values stay within the published limit of one trillion, and the list length is capped so a Worker can finish quickly. On success the response echoes rounded amounts, scaled, scale_factor, original_servings, target_servings, count, optional names, ingredients rows pairing each original amount with its scaled value, formula, message, and ordered steps for audit trails. Failed validation—empty amounts, non-finite numbers, non-positive servings or amounts, or missing required fields—returns invalid_input with a message naming the problem. Pricing is a flat $0.002 per successful request with unit item and zero marginal unit price.

Practical tips, common mistakes, limits, and related tools

When scaling for guests, double-check that every line on the card is proportional—some recipes leave seasonings to taste or fix pan size, so you may scale bulk ingredients and leave spice pinches as judgment calls. Prefer numbers rather than pre-formatted unit strings inside amounts; put units in the optional names field instead. Prefer sibling cook or convert tools when you need flour cups to grams or tablespoons to millilitres, then scale the resulting numbers here. Round-trip checks are easy: recompute each amount times factor by hand and confirm it equals the published scaled entry within the same twelve-decimal rounding, and confirm that changing only the target scales every line proportionally while leaving labels aligned. Always keep original_servings non-zero and positive in client forms before submit; the API will still throw a clear invalid_input message if zero or a negative count slips through, because dividing by zero or inventing a negative batch is not a meaningful scale. Failed tasks that return invalid_input do not consume prepaid balance, which keeps exploratory scripts cheap when learners deliberately send zero servings or empty lists. For catering, convert a pilot batch written for eight plates into a service count of forty-eight by sending original_servings eight and target_servings forty-eight so factor is derived automatically without a separate multiplier field.