Pearson Square

Science Byte

A quick way to calculate a target milkfat content for cheesemaking

We’ve already discussed standardization a bit in the past. The basic concept is that a cheese maker will alter the starting composition of their milk before they make cheese. This could be done for quality control reasons, economic reasons, or for legal reasons.


An example of a Pearson Square calculation. Read below for more info.

The most common method of milk standardization is changing its fat content. This is accomplished by adding/removing cream or skim milk. For example, a cheese maker might want to make cheese using a milk with a fat content of 3.2%. Their starting milk has a fat content of 3.8%. They need to know how much skim milk to add to bring the fat content down to their target of 3.2%. The Pearson Square method is just a way to organize the numbers to make the math easier to understand. The image above is using our example we just discussed. So in this case the cheese maker would need to mix together 82% of their starting milk with 18% of skim milk to reach their target. Try out your own mixture below!

% Fat in Milk
Parts Whole Milk:
% Fat required
% Fat in Skim
Parts Skim Milk: 0.60

Plug in your own numbers in the gray boxes.

Total Mix (lbs)
Whole Milk (lbs):
Skim Milk (lbs):

Calculate how much milk you need to mix given your final amount needed.

This method could also be used to calculate how much cream you need to add to milk for cheeses made with higher fat milks. In fact, the Pearson Square method isn't just for dairy-related calculations. It can be used to calculate components of any mixture: wine making, spirit fortification, animal feed to name a few.


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