Methodology & Data Sources

This page documents the data sources, formulas, and assumptions behind every calculator and ingredient weight on this site. If you find an error, please contact us.

Ingredient Weights (Cups to Grams)

Primary source: King Arthur Baking Ingredient Weight Chart. This is the most widely cited professional reference for US baking ingredient weights and is updated periodically by King Arthur's test kitchen staff.

Secondary source: USDA FoodData Central, used for ingredients not covered by King Arthur's chart.

Measuring method assumed: The spoon-and-level method for dry ingredients (spoon ingredient into the measuring cup with a separate spoon, level off with a straight edge). This is the standard professional method. Scooping can increase weight by 20–30%.

Cup size: US legal cup = 240 mL (236.6 mL exactly). All values use the US cup definition.

Butter Converter

1 US stick = 113 g = 8 tbsp = ½ cup = 4 oz (industry standard)
European 250 g block used as-is (no further conversion)
Source: USDA, major US butter manufacturers (Land O'Lakes, Challenge Dairy)

Yeast Converter

Instant : active dry : fresh = 1 : 1.25 : 3 by weight
Source: King Arthur Baking; consistent with SAF and Fleischmann's published guidelines
1 standard packet (US) = 7 g = 2¼ tsp
Sourdough starter conversion is approximate (10× instant weight in 100% hydration starter); actual conversion depends on starter activity and recipe

Oven Temperature Converter

°F ↔ °C: exact formula (°F − 32) × 5/9
Gas mark scale: Regulo scale, where Gas 1 ≈ 275°F, each mark ≈ +25°F
Convection adjustment: −25°F / −15°C; standard industry guidance

Pan Size Converter

Round pan area: π × (diameter/2)²
Rectangle area: width × length
Bundt approximation: outer area − inner tube area
Multiplier = target area ÷ original area
Bake time guidance is qualitative (deeper = longer, shallower = shorter); exact adjustment requires testing

Baker's Percentage Calculator

Baker's % = (ingredient weight ÷ flour weight) × 100
Levain contribution calculated from levain hydration: flour in levain = levain weight ÷ (1 + hydration); water in levain = levain weight − flour in levain
Total hydration includes water from levain

Sourdough Schedule

Bulk ferment model: Q10 kinetics (reaction rate doubles per 10°C / 18°F change). Base case: 5 hours at 76°F with 20% starter (100% hydration levain, based on documented observations from Maurizio Leo, The Perfect Loaf, W.W. Norton, 2022, and King Arthur Baking)
Starter factor: logarithmic adjustment for starter percentage
Output is an estimate. Actual fermentation time depends on flour protein content, starter activity, ambient humidity, and other variables. Always judge by visual and tactile cues.

Recipe Scaler

All ingredients scale linearly (multiplier = target ÷ original servings)
Unit conversions: 3 tsp = 1 tbsp, 16 tbsp = 1 cup, 4 cups = 1 quart
Egg fractional amounts: 50 g per US large egg (USDA standard), converted to tablespoons at 14.787 g/tbsp
Fraction display: tolerance ±4% of standard fraction values

Recipe Cost Calculator

Cost per gram = package price ÷ package weight (in grams)
Unit conversions: 1 oz = 28.35 g, 1 lb = 453.59 g, 1 cup = 236.6 mL (treated as mL ≈ g for liquids)
Count-based items (eggs, etc.) are treated as discrete units
Price suggestion = food cost × markup; does not include labor, overhead, or packaging unless added as ingredients

Update Cadence

Ingredient weights are reviewed when King Arthur Baking or USDA update their reference data. Calculator formulas are reviewed quarterly or when errors are reported. The site last reviewed all weights in October 2026.

Reporting Errors

If you find a discrepancy between our values and a primary source, please contact us with the ingredient name, our value, the correct value, and the source URL. We will investigate and correct within 5 business days.