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How the Recipe Scaler Works

How recipe ingredients are scaled proportionally between serving sizes, with USDA nutritional data and worked examples.

Verified against USDA FoodData Central on 15 Feb 2026 Updated 15 February 2026 3 min read
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The Recipe Scaler adjusts ingredient quantities when you need more or fewer servings than a recipe makes. Enter your recipe’s ingredients with gram weights, set the original and target serving counts, and see scaled amounts instantly — along with per-serving and total nutritional information from the USDA FoodData Central database.

Cum funcționează

  1. Add ingredients — search the 142-food USDA database and add foods to your recipe with gram weights per total recipe.
  2. Set servings — enter how many servings the original recipe makes and how many you want.
  3. See scaled amounts — every ingredient is multiplied by the scale factor. Nutritional totals (calories, macros) update live for both the total recipe and per serving.

The scaling formula

scaled_amount = original_amount × (target_servings ÷ original_servings)

Where

original_amount= The ingredient weight in grams as entered for the original recipe
target_servings= The number of servings you want
original_servings= The number of servings the recipe originally makes

The ratio target_servings ÷ original_servings is the scale factor. If a recipe makes 4 servings and you want 6, the scale factor is 1.5 — every ingredient is multiplied by 1.5.

Nutritional calculation

All nutrient values in the database are stored per 100g. To calculate nutrients for a given portion:

nutrient_portion = nutrient_per_100g × portion_grams ÷ 100

Where

nutrient_per_100g= The nutrient value per 100g from the USDA database
portion_grams= The scaled weight of the ingredient in grams

Total recipe nutrition is the sum of all scaled ingredient values. Per-serving nutrition divides the total by the target serving count.

Macro energy percentages

The protein/carbs/fat energy split uses the Atwater general factors — the standard system for food energy labelling (EU Regulation 1169/2011, FAO):

total_energy = protein × 4 + carbs × 4 + fat × 9 (kcal)

Where

protein × 4= Protein provides 4 kcal per gram
carbs × 4= Carbohydrates provide 4 kcal per gram
fat × 9= Fat provides 9 kcal per gram

Exemplu rezolvat

A chicken stir-fry recipe makes 4 servings. You want 6 servings (scale factor = 1.5).

Original recipe: 400g chicken breast + 600g brown rice (cooked) + 200g broccoli.

Scaling 4 → 6 servings (factor 1.5×)

1

Chicken breast, raw (400g → 600g)

400 × 1.5 = 600g. Calories: 120 × 600 ÷ 100 = 720.0 kcal

= 600g, 720.0 kcal

2

Brown rice, cooked (600g → 900g)

600 × 1.5 = 900g. Calories: 123 × 900 ÷ 100 = 1107.0 kcal

= 900g, 1107.0 kcal

3

Broccoli, raw (200g → 300g)

200 × 1.5 = 300g. Calories: 34 × 300 ÷ 100 = 102.0 kcal

= 300g, 102.0 kcal

Result

Total: 1929 kcal, 167.7g protein, 250.2g carbs, 25.8g fat. Per serving: 322 kcal.

Macro energy split (per serving, Atwater 4-4-9):

  • Protein: 28.0 × 4 = 111.8 kcal → 35.2%
  • Carbs: 41.7 × 4 = 166.8 kcal → 52.6%
  • Fat: 4.3 × 9 = 38.7 kcal → 12.2%

Intrări explicate

  • Recipe makes (servings) — how many servings the original recipe produces. Default: 4.
  • I want (servings) — how many servings you need. Quick-select buttons for common counts (1, 2, 4, 6, 8, 12).
  • Ingredients — search and add foods from the USDA database. Enter the gram weight per total recipe (not per serving).

Rezultate explicate

  • Scale factor — shown when target differs from original (e.g. “1.5× scaling up”).
  • Ingredient table — original and scaled gram weights side by side.
  • Per serving nutrition — calories (hero number), protein, carbs, fat, fiber with macro energy percentages.
  • Total recipe nutrition — summed across all ingredients for the full scaled recipe.

Ipoteze și limitări

  • Linear scaling — all ingredients scale proportionally by the same factor. This is mathematically exact but may not suit all recipes: seasoning and spices often need less-than-proportional increases, and baking recipes with yeast or leavening agents may not scale well beyond 2–3×.
  • Gram weights only — the calculator works in grams for precision. Volume measures (cups, tablespoons) are not supported because they vary by ingredient density.
  • USDA data — nutrient values are for generic foods, not branded products. Actual values vary by growing conditions, cooking method, and brand.
  • Raw vs cooked — select the form matching how you measure the ingredient. 100g raw chicken ≠ 100g cooked chicken in nutritional content.
  • 142 foods — the database covers common whole foods. Processed, branded, and restaurant foods are not included.
  • No cooking losses — the calculator does not account for moisture loss, fat rendering, or nutrient degradation during cooking. Scaled weights are pre-cooking weights.

Verificare

Test caseInputExpectedSource
Double recipe4→8 servings, 200g ingredient400gManual: 200 × 2.0
Scale down6→2 servings, 300g ingredient100gManual: 300 × 0.333
Scale up 1.5×4→6 servings, 250g ingredient375gManual: 250 × 1.5
Round-trip2→5→2 servings, 150g150gIdentity: scale up then back
Macro % sumAny non-empty recipe100%Atwater identity
Full recipe4→6 servings, chicken+rice+broccoli1929 kcal totalCalc function verified

Sources

recipe-scaler nutrition scaling servings ingredients usda