Pellet Die Compression Ratio Calculator
Compression ratio (L/D) is the working thickness of the die divided by the hole diameter. It is the single biggest driver of how hard your pellet runs. Enter your die and this tells you the ratio and how it reads.
Your die
Use the effective (working) length: the total die thickness minus any counterbore or relief on the inlet side.
Compression ratio
What compression ratio tells you
The rolls push mash through the holes in the die. A longer hole relative to its diameter means the feed spends more time under pressure and friction, so the pellet comes out harder and more durable. A shorter hole lets feed pass easily, giving a softer pellet and higher throughput. That relationship is the compression ratio, written as working length to hole diameter, for example 10:1.
Higher is not automatically better. Push the ratio too high for a given ration and the mill loads up, capacity drops, and the die can plug or choke. Too low and the pellet falls apart in handling. The right number depends on the formula, and fat and fiber move it the most: added fat lubricates the die and calls for a higher ratio to hold pellet quality, while high fiber grips the die and calls for a lower one.
Typical ranges by application
Use these as a starting point, then confirm with your die supplier for your exact formula.
| Application | Typical L/D |
|---|---|
| High-fat or high-molasses rations | 6:1 to 8:1 |
| Cattle and range cubes | 7:1 to 9:1 |
| General poultry and swine feed | 9:1 to 12:1 |
| Hard, durable pellets and aquafeed | 12:1 to 15:1 |
Frequently asked
Which thickness do I use, total or effective?
Use the effective working thickness. If your die is relieved or counterbored on the feed side, subtract that relief from the total thickness, because only the straight part of the hole does the compressing.
Does hole diameter change the ratio on its own?
Yes. For the same die thickness, a smaller hole gives a higher ratio and a harder pellet. That is why a die that runs well for one product can run tight or loose when you switch pellet sizes.
Note: compression ratio is a guide, not a guarantee. Die material, hole finish, feed formula, conditioning, and roll setting all affect the result. Always confirm die specifications with the manufacturer before ordering.
Not sure which die your ration needs?
Chandler Adams reps CPM dies and pellet mills. Tell us your formula and target and we will help you spec it.