Weighing and Scaling

Weighing and Measuring

Introduction to Weighing in Baking

Weighing and measuring constitute the first critical step in any bakery production. The precision of measurements directly determines the quality, consistency, and profitability of finished products. As a Red Seal baker, you must master not only weighing techniques but also the metrological principles that underpin these operations.

In this chapter, you will learn the fundamental principles of weighing, the different types of instruments, calibration procedures, unit conversions, and formulation calculations — all the essential knowledge to succeed on the Red Seal exam.

Fundamental Principles of Measurement

Mass, Weight, and Volume

It is essential to distinguish between three different physical quantities:

Quantity	Definition	SI Unit	Measuring Instrument
Mass	Amount of matter in a body	Kilogram (kg)	Scale
Weight	Gravitational force exerted on a body	Newton (N)	Dynamometer
Volume	Space occupied by a body	Litre (L) or cubic metre (m³)	Graduated cylinder, measuring cup

The relationship between weight and mass is: W = m × g, where g represents gravitational acceleration (approximately 9.81 m/s² at the Earth's surface). In baking, the term "weight" is commonly used to refer to mass, and this simplification is acceptable in professional practice, but you must understand the conceptual distinction.

Precision, Accuracy, and Resolution

Three distinct metrological concepts:

Precision: the ability of an instrument to produce repeatable results (low dispersion of measurements).

Accuracy: the closeness between the measured value and the true value (low systematic error).

Resolution: the smallest change in mass that an instrument can detect and display.

An instrument can be precise without being accurate (constant systematic error), and vice versa. For the exam, remember that the resolution of a scale must be appropriate for the smallest quantity you need to weigh in your recipe.

Weighing Instruments

Mechanical Scales

Mechanical scales operate by comparing masses or by spring deformation. They include:

Roberval balance: fixed platform, precision of ±0.1 g, used for small quantities.

Spring scale: less precise (±2 g), sensitive to temperature and spring wear.

Beam balance: direct comparison with standard masses, very precise but slow.

Electronic (Digital) Scales

Electronic scales use load cells (strain gauges) that convert force into an electrical signal. Their precision ranges from ±0.01 g (precision scales) to ±5 g (industrial scales).

Important characteristics:

Characteristic	Precision Scale	Counter Scale	Industrial Scale
Resolution	0.01 g	0.1 to 1 g	1 to 5 g
Maximum capacity	100 to 500 g	5 to 15 kg	50 to 500 kg
Use	Expensive ingredients, yeast	Daily weighing	Flour bags, dough
Calibration	Daily	Weekly	Monthly

Verification and Calibration

Calibration is the operation of adjusting the instrument so that its readings correspond to reference values. Verification is the periodic check of accuracy.

Daily verification procedure:

29.Level the scale (bubble centred).

30.Turn on and wait for stabilization (usually 30 seconds).

31.Place a known standard mass (e.g., 1 kg) in the centre of the platform.

32.Compare the reading to the expected value.

33.If the deviation exceeds the tolerance (±1 division), proceed with calibration.

Calibration is performed using certified standard masses (classes E1, E2, F1, F2 according to OIML R111). In baking, class F2 masses are generally sufficient.

Units of Measurement and Conversions

Metric System

The International System of Units (SI) is mandatory in Canada for commercial transactions. The base units in baking:

Quantity	Unit	Sub-multiples	Multiples
Mass	kilogram (kg)	g, mg	t (tonne = 1000 kg)
Volume	litre (L)	mL, cL, dL	hL (hectolitre = 100 L)
Temperature	degree Celsius (°C)	—	—

Essential Conversions

Mass conversions:

1 kg = 1000 g

1 g = 1000 mg

1 tonne = 1000 kg

1 lb = 453.592 g ≈ 454 g

1 oz = 28.3495 g ≈ 28.35 g

Volume conversions:

1 L = 1000 mL

1 L = 100 cL

1 m³ = 1000 L

1 US gal = 3.785 L

1 imp gal = 4.546 L (Canadian imperial gallon)

Temperature conversions:

°F = (°C × 9/5) + 32

°C = (°F − 32) × 5/9

Density and Mass per Unit Volume

Density (ρ) is the ratio between the mass and the volume of a substance: ρ = m/V. It is expressed in g/mL or kg/L.

Substance	Density (g/mL)
Water (4 °C)	1.00
All-purpose flour (packed)	0.55 to 0.60
All-purpose flour (sifted)	0.45 to 0.50
Granulated sugar	0.85
Icing sugar	0.50 to 0.60
Salt	1.20
Dry yeast	0.60 to 0.70
Vegetable oil	0.92
Milk	1.03
Honey	1.40

Exam trap: the density of flour varies considerably depending on packing, humidity, and measuring method. This is why professional recipes are always expressed by mass, never by volume, for dry ingredients.

Formulation Calculations

Baker's Percentages (Basic Formula)

The baker's percentage is a calculation system where flour always represents 100% and all other ingredients are expressed as a percentage of the flour mass.

Formula: Percentage of an ingredient = (mass of ingredient ÷ total mass of flour) × 100

Example: Recipe with 5000 g of flour and 3000 g of water:

Water percentage = (3000 ÷ 5000) × 100 = 60%

Calculating Total Dough Mass

Total dough mass is calculated by adding the masses of all ingredients, or by using the total percentage:

Total mass = flour mass × (total percentage ÷ 100)

Example: Flour = 5000 g, total percentage = 185%

Total mass = 5000 × (185 ÷ 100) = 9250 g

Reverse Calculation: Determining Flour Quantity

To produce a target quantity of dough:

Flour mass = total dough mass ÷ (total percentage ÷ 100)

Example: You need to produce 50 kg of dough with a total percentage of 180%:

Flour mass = 50,000 ÷ (180 ÷ 100) = 50,000 ÷ 1.8 = 27,778 g ≈ 27.8 kg

Adjusting a Recipe

To adapt a recipe to a different production quantity, use a conversion factor:

Factor = desired mass ÷ current mass

Each ingredient is then multiplied by this factor.

Example: Original recipe = 10 kg of dough, desired = 35 kg:

Factor = 35 ÷ 10 = 3.5

Each ingredient is multiplied by 3.5.

Weighing Procedures in Production

Weighing Dry Ingredients

84.Use clean, dry containers.

85.Place the empty container on the scale and perform the tare (zeroing).

86.Add the ingredient gradually until the target mass is reached.

87.For small quantities (baking powder, salt), use a spoon or spatula to avoid overshooting.

88.Immediately record the mass on the production sheet.

Weighing Liquids

Use a graduated container for large volumes, or weigh directly on the scale.

The tare must include the container.

For water, 1 mL = 1 g (at room temperature), which makes conversions easy.

Viscous liquids (honey, molasses) must be weighed, never measured by volume, due to their adherence to container walls.

Weighing Yeast

Yeast is a critical ingredient whose weighing precision directly influences fermentation:

Type of Yeast	Required Precision	Notes
Fresh yeast (compressed)	±1 g	Keep refrigerated (2 to 4 °C)
Active dry yeast	±0.5 g	Rehydrate before use
Instant yeast	±0.5 g	Add directly to flour

Managing Weighing Errors

Weighing errors can be:

Systematic: due to a poorly calibrated instrument, incorrect tare, or unstable surface.

Random: due to variations in handling, air currents, or vibrations.

Gross: reading errors, transposed numbers, or unit confusion.

Procedure in case of error:

103.Never attempt to "compensate" by modifying another ingredient without recalculating the entire formula.

104.If the error is detected before mixing, remove the excess or add the missing quantity.

105.If the error is detected during mixing, assess the impact on consistency and adjust with flour or water as appropriate.

106.Document any modification on the production sheet.

Canadian Standards and Regulations

Weights and Measures Act (Canada)

The Weights and Measures Act (R.S.C. 1985, c. W-6) governs all measuring instruments used in commerce in Canada. Key points for the baker:

All weighing instruments used for commercial transactions must be approved by Measurement Canada.

Scales must be verified periodically by an authorized inspector.

Using an unverified or unapproved instrument constitutes an offence.

Pre-packaged products must comply with the fill tolerances established by the Pre-packaged Products Regulations (SOR/2001-273).

Pre-packaged Products Regulations

These regulations require that:

The net quantity be declared in metric units.

The fill tolerance for bakery products be respected (generally ±5% for products under 500 g, ±3% for products from 500 g to 10 kg).

The label indicate the net quantity, the product name, and the manufacturer's identification.

Food Safety Standards

The Canadian Code of Safe Food Handling Practices (Interpretation Guide) requires that scales be:

Cleaned and sanitized regularly to prevent cross-contamination.

Checked for accuracy at least once per work shift.

Protected against flour dust (explosion and contamination risk).

Temperature and Measurement

Thermometers in Baking

Type of Thermometer	Range	Precision	Use
Digital probe	−50 to 300 °C	±0.5 °C	Dough, water, oven
Infrared	−50 to 550 °C	±2 °C	Oven surface, hot bread
Stem (liquid)	−10 to 110 °C	±1 °C	Mixing water
Dial	0 to 200 °C	±2 °C	Oven (less precise)

Base Dough Temperature

Base temperature is a calculation method used to achieve a consistent dough temperature after mixing, regardless of ambient temperature.

Simplified formula: Base temperature = (Desired dough temperature × 4) − (Flour temperature + Ambient temperature + Room temperature + Friction factor)

The friction factor is a constant specific to each mixer, determined experimentally. It represents the heat generated by mechanical friction.

Calculating water temperature:

Water temperature = (Base temperature) − (Flour temperature + Ambient temperature + Friction factor)

Example: Base temperature = 58 °C, flour = 20 °C, ambient = 22 °C, friction = 8 °C:

Water temperature = 58 − (20 + 22 + 8) = 58 − 50 = 8 °C

pH Measurement

pH measures the acidity or alkalinity of a solution on a scale of 0 to 14. In baking, pH is particularly important for:

Sourdough starters: optimal pH between 3.8 and 4.2.

Fermented doughs: pH between 4.5 and 5.5.

Standard bread dough: pH between 5.5 and 6.0.

Measurement is performed with a pH meter calibrated with buffer solutions (pH 4.0 and pH 7.0). Calibration must be performed before each series of measurements.

Moisture Measurement

Flour Moisture Content

The moisture content of flour directly affects the water absorption of the dough. Canadian standards require a maximum moisture content of 14% for wheat flour (Bakery Products Regulations).

Measurement method: oven drying at 130 °C for 1 hour, then calculating the mass loss.

Formula: Moisture content (%) = [(initial mass − dry mass) ÷ initial mass] × 100

Relative Humidity of the Room

The relative humidity (RH) of the fermentation room influences surface evaporation from doughs. The optimal range for fermentation is 70 to 80% RH.

The hygrometer must be checked regularly. A psychrometer (two thermometers, one dry and one wet) provides accurate measurement through temperature difference.

Ingredient Management and Inventory

FIFO Method (First In, First Out)

Stock rotation using the FIFO method is mandatory to ensure ingredient freshness and prevent losses. Each batch of ingredients must be identified with:

The date of receipt.

The expiry date.

The lot number.

Calculating Yield

Yield is the ratio between the mass of the finished product and the total mass of ingredients:

Yield (%) = (finished product mass ÷ total ingredient mass) × 100

Normal losses in baking (evaporation, adherence, spillage) typically represent 5 to 10% of the total mass.

Calculating Ingredient Cost

Unit cost = purchase price ÷ total quantity

Cost per recipe = Σ (mass of each ingredient × unit cost)

Example: Flour at $0.80/kg, recipe using 25 kg:

Flour cost = 25 × 0.80 = $20.00

Pitfalls to Avoid

165.Confusing mass and volume for dry ingredients. Flour weighs approximately 550 g per litre, not 1000 g. A volume error can result in a 45% error in actual mass.

166.Forgetting the tare of the container. An untared 500 g bowl will skew all measurements.

167.Using an uncalibrated scale after it has been moved or dropped. Always check with a standard mass before use.

168.Confusing the US gallon and the imperial gallon. The imperial gallon (used in Canada) equals 4.546 L, while the US gallon equals 3.785 L. Confusing them results in a 20% error.

169.Neglecting water temperature in calculations. Water that is too hot (above 30 °C) can deactivate yeast; water that is too cold excessively slows fermentation.

170.Over-rounding conversions. For small quantities (baking powder, salt), rounding to the nearest 0.1 g is necessary.

171.Ignoring the friction factor when calculating water temperature. Each mixer has its own factor, which must be determined and documented.

172.Using measuring cups and spoons for professional ingredients. These instruments are imprecise (±10%) and are not acceptable in commercial production.

173.Not documenting weighings. Traceability is essential for quality control and reproducibility.

174.Weighing hot ingredients directly on the scale. Thermal convection distorts readings on electronic scales.

Summary

Precise weighing is the foundation of professional baking. All ingredients must be weighed by mass, never measured by volume, except for liquids under certain controlled conditions.

The baker's percentage is the universal calculation tool: flour represents 100% and all other ingredients are expressed as a proportion of the flour.

Electronic scales must be verified daily with standard masses and calibrated periodically. Resolution must be appropriate for the smallest quantity being weighed.

Unit conversions must be mastered perfectly, particularly between the metric system and imperial units (1 lb = 454 g, 1 imp gal = 4.546 L).

Base temperature allows you to control the final dough temperature by adjusting the mixing water temperature.

The Weights and Measures Act and the Pre-packaged Products Regulations impose legal requirements for all measuring instruments and product labelling.

Yield and ingredient cost are essential calculations for the economic management of production.

Documentation of all weighings and adjustments is indispensable for traceability and consistent quality.

Canadian standards (Measurement Canada, Canadian Code of Safe Food Handling Practices) legally govern all weighing and measuring operations in baking.

Mastery of formulation calculations (recipe adjustment, conversion factor, total dough mass) is a skill directly assessed on the Red Seal exam.

To succeed on the exam, practice performing these calculations quickly and without a calculator, as the time allotted per question is limited. Regular practice of conversions and baker's percentage calculations is the best preparation.