How do you calculate pellet durability loss rate?

Divide the count of fines and broken pellets by the total pellets in the sieved sample, then multiply by 100. With 8 broken pellets out of a 250-pellet sample, the loss rate is 8 ÷ 250 × 100 = 3.2%, which corresponds to a PDI of about 96.8%.

What is a good pellet durability loss rate?

For most poultry and swine feed, a loss under 4% (PDI above 96%) is considered good, and premium aquafeed often targets under 2%. The 3.2% in our example is solid for livestock pellets but would be borderline for extruded aquafeed.

What is the difference between durability loss and PDI?

They are two sides of the same test. PDI is the percentage of pellets that stay intact; durability loss is the percentage that break. A 3.2% loss equals a 96.8% PDI.

Why is my durability loss rate suddenly higher?

The usual culprits are a worn or over-drilled die, low conditioning temperature or steam, insufficient residence time, low fat that no longer lubricates, or a formula short on natural binders like wheat gluten. Check die condition and conditioner steam first.

How big should a durability test sample be?

Standard methods use a fixed mass (typically 500 g) rather than a fixed count, but a representative sieved sample of at least a few hundred pellets gives a stable rate. Small samples make each broken pellet swing the percentage too much.

Does higher durability always mean better pellets?

Not always. Chasing very high durability with heavy binder or over-conditioning can hurt palatability, water stability, or digestibility, and it costs energy. Match the target to the species and handling chain, not to the highest possible PDI.

Pet Food & Animal Nutrition Manufacturing calculator

Pellet durability loss Calculator

Pellet durability loss is the share of a pellet sample that crumbles into fines and broken pieces during a standardized durability test such as a tumbling box or Holmen tester, and it is the direct inverse of the Pellet Durability Index (PDI) that pet food and animal feed plants live by. Process engineers, pelleting and extrusion operators, and QA teams use it to judge whether finished kibble, aquafeed, or livestock pellets will survive bagging, augering, and transport without generating dust and complaints. A rising loss rate is an early warning that die condition, conditioning steam, moisture, or binder inclusion has drifted. Because fines mean wasted starch gelatinization energy and rejected loads, this number ties directly to yield and margin.

What this calculator does

Estimate pellet durability loss for pet food and animal nutrition manufacturing using production-ready inputs so teams can track KPI performance and decide whether corrective action is needed.
Use it when pellet durability loss in pet food and animal nutrition manufacturing needs a clean rate and gap-to-target you can put on a tier board.
It computes the percentage of a durability test sample lost as fines and broken pellets, then compares that loss rate against your target durability spec.

Formula used

Pellet durability loss rate = pellet durability loss count ÷ total pellet durability loss population × 100
Pellet durability loss gap to target = pellet durability loss rate - target pellet durability loss rate

Inputs explained

Fines and broken pellets after tumbling:
Total pellets in durability test sample:
Target maximum durability loss rate:

How to use the result

Use it on every pelleting or extrusion run when you pull a durability sample, and whenever you change die geometry, conditioning steam, formula binder, or dryer settings.
The result is only as valid as the test method and sample handling; Holmen and tumbling-box testers give different absolute numbers, so never benchmark a Holmen loss rate against a tumbling-box target.

Current U.S. benchmarks

Industrial natural gas averages $4.9 per Mcf (EIA, Apr 2026), down 7.7% from a year earlier, with industrial electricity at 8.66 cents per kWh. Process heating and refrigeration budgets track both.
The U.S. has 31,130 food manufacturing establishments employing about 1,707,316 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate pellet durability loss rate? Divide the count of fines and broken pellets by the total pellets in the sieved sample, then multiply by 100. With 8 broken pellets out of a 250-pellet sample, the loss rate is 8 ÷ 250 × 100 = 3.2%, which corresponds to a PDI of about 96.8%.
What is a good pellet durability loss rate? For most poultry and swine feed, a loss under 4% (PDI above 96%) is considered good, and premium aquafeed often targets under 2%. The 3.2% in our example is solid for livestock pellets but would be borderline for extruded aquafeed.
What is the difference between durability loss and PDI? They are two sides of the same test. PDI is the percentage of pellets that stay intact; durability loss is the percentage that break. A 3.2% loss equals a 96.8% PDI.
Why is my durability loss rate suddenly higher? The usual culprits are a worn or over-drilled die, low conditioning temperature or steam, insufficient residence time, low fat that no longer lubricates, or a formula short on natural binders like wheat gluten. Check die condition and conditioner steam first.
How big should a durability test sample be? Standard methods use a fixed mass (typically 500 g) rather than a fixed count, but a representative sieved sample of at least a few hundred pellets gives a stable rate. Small samples make each broken pellet swing the percentage too much.

Last reviewed 2026-05-12.