Pearson's Square Calculator

Milk fat standardisation on a mass basis. Enter fat as % by mass (% w/w) and batch mass in kg.

Inputs

Higher-fat milk

% fat by mass. Example: milk at 4.0%.

Lower-fat milk (e.g. skim)

% fat by mass. Skim: 0.05–0.5%

Target fat content

% fat by mass. UK whole milk: 3.5–4.0%

Total batch mass in kg (optional)

Kilograms only. Leave blank to see proportions by mass.

Parts higher-fat milk—

Parts lower-fat milk—

Higher-fat quantity—

Lower-fat quantity—

Enter the three fat percentages to calculate the blend.

The Pearson's Square

Higher fat4.0

↘

Parts high—

↙

Target3.5

↗

Lower fat0.1

↖

Parts low—

Higher-fat ratio	—
Lower-fat ratio	—
Total parts	—
Verification (calculated fat %)	—

Method: Subtract diagonally. Top right: Target − Lower = parts of higher-fat milk. Bottom right: Higher − Target = parts of lower-fat milk. Parts are proportions by mass.

Check the result before using the blend

Use representative fat tests from the two ingredients and enter the required final batch mass. Weigh additions in kilograms; litres require a separate density conversion for each stream.

Check the fat balance: ingredient mass × fat percentage ÷ 100 gives kilograms of fat. Add the two fat masses and divide by final blend mass. Verify a representative sample after adequate mixing.

A 10,000 kg batch at 3.55% contains 5 kg more milk fat than one at 3.50%. Investigate unexpected results through sampling, weighing, meter calibration and valve checks.

Practical standardisation checks and correcting an existing batch