6mm vs 8mm Wood Pellets: Which Diameter Should You Buy?

Wood pellet diameter is set by the die used in the pellet mill. The two commercial diameters are 6 mm and 8 mm — same feedstock, different application.

6 mm pellets

The residential standard. Fits every certified pellet stove and small boiler. Better flow through narrow augers. ~99% of ENplus A1 bagged product is 6 mm.

8 mm pellets

Used in industrial and large commercial boilers where higher throughput matters more than fine metering. Slightly cheaper to produce (less die wear, higher output per hour), which shows up in bulk price.

Practical rule

Never buy 8 mm for a residential stove without confirming compatibility — the auger and burner geometry may not accept the larger pellet, and you'll void the warranty.