GIFSQ Tools · Module 2 — Food Chemistry & Physicochemical Testing · Tool 33 of 500
Enter repeat viscosity readings from the same sample and get the mean, the sample standard deviation and the coefficient of variation.
Try sample values — fills the form with the worked example below.
All three readings share one unit selector. Enter at least two readings.
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Mean viscosity (mPa·s)
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Standard deviation (mPa·s)
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Coefficient of variation (%)
Equation: Mean = Σx ÷ n. Sample SD = √[Σ(x − mean)² ÷ (n − 1)]. Coefficient of variation % = SD ÷ mean × 100. For a Newtonian fluid, viscosity η = shear stress ÷ shear rate, with 1 Pa·s = 1000 mPa·s and 1 cP = 1 mPa·s.
Method: Rotational viscometry, ISO 2555 / ASTM D2196 — repeat readings at the stated spindle, speed and temperature; report the mean with the sample SD (÷ n−1).
Assumptions: readings are repeats of the same sample at the same temperature, spindle and speed; the fluid is at steady flow when read.
Limitations: a mean hides shear-thinning behaviour — a single viscosity number does not describe a non-Newtonian food; temperature drift between readings widens the SD; n = 2 gives a weak SD.
Rounding: mean and SD to 2 decimal places, coefficient of variation to 2 decimal places; intermediate values are not rounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: Rotational viscometry, ISO 2555 / ASTM D2196 — repeat readings at the stated spindle, speed and temperature; report the mean with the sample SD (÷ n−1).
Assumptions: readings are repeats of the same sample at the same temperature, spindle and speed; the fluid is at steady flow when read.
Limitations: a mean hides shear-thinning behaviour — a single viscosity number does not describe a non-Newtonian food; temperature drift between readings widens the SD; n = 2 gives a weak SD.
Rounding: mean and SD to 2 decimal places, coefficient of variation to 2 decimal places; intermediate values are not rounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: Three readings on a sauce: 120, 124 and 122 mPa·s. Mean = 366 ÷ 3 = 122.00 mPa·s; SD = √[(4 + 4 + 0) ÷ 2] = 2.00 mPa·s; coefficient of variation = 2.00 ÷ 122.00 × 100 = 1.64 %.
Enter values above to see results.
Typical viscosities at 20 °C: water about 1 mPa·s, milk about 2 mPa·s, honey about 10,000 mPa·s. Always record spindle, speed and temperature with the reading. Tool 33 of 500 — GIFSQ
