Pearson square calculator
Enter the protein content of two feeds, one below and one above the level you want, and the target for the mix. The calculator does the Pearson square for you and gives each feed's share and its amount in a batch of any size and unit.
Runs in your browser: nothing you enter is sent anywhere.
How to use
- Enter the nutrient content of feed A and feed B, for example crude protein in per cent.
- Enter the target for the mix; it must lie between the two.
- Enter the batch size in any unit and read the shares and amounts.
How it works
- parts of A = |B − target|; parts of B = |A − target|;
- share of A = parts of A ÷ (parts of A + parts of B), and likewise for B;
- amount = share × batch size.
Example
Corn at 9 % crude protein and soybean meal at 44 %, for a 16 % mix, 1,000 kg batch:
- parts of corn = 44 − 16 = 28; parts of soybean meal = 16 − 9 = 7; total 35;
- corn 28 ÷ 35 = 80 %, soybean meal 7 ÷ 35 = 20 %;
- batch: 800 kg corn and 200 kg soybean meal.
Check: 0.8 × 9 + 0.2 × 44 = 7.2 + 8.8 = 16 %.
Tips and common mistakes
- Use real analysis figures for your feeds when you can; book values are averages.
- Keep the basis the same: do not mix an as-fed figure for one feed with a dry-matter figure for the other.
- The square balances one nutrient. Check the others (energy, minerals) separately.
Frequently asked questions
How does the Pearson square work?
Write the target in the middle of a square and the two feeds on the left corners. Subtract diagonally, ignoring signs: each difference is the number of parts of the feed on the opposite corner. Divide each by the total parts to get the shares.
Can I use it for something other than protein?
Yes: energy, fat, fibre, calcium or any nutrient that mixes in proportion to weight. Use the same basis (as-fed or dry matter) for both feeds and the target.
Why must the target lie between the two feeds?
A mix of two feeds can only land between them. If you need 16 % protein, one feed must be below 16 % and the other above it.
What if I need minerals or a third feed?
Set aside the fixed part of the ration (a mineral premix, say), work out the target for the rest and use the square for the two main feeds. For many ingredients at once a ration-balancing program is better.