Biomass pellets usually come in 6, 8 and 10 mm diameters. The right size depends on how your boiler feeds fuel and how much heat you need — not on which pellet looks best.
6 mm pellets
Best for small burners, domestic and commercial heaters, and feeders with narrow screws. They ignite quickly and flow easily through small hoppers.
8 mm pellets
The most common size for industrial pellet boilers. A good balance of flow, burn time and handling for most automatic systems.
10 mm pellets
Used in large boilers and high-throughput feeding systems, where a slightly longer burn per pellet is an advantage.
Three questions to ask before you order
- What does your burner manufacturer recommend? Check the manual or nameplate first.
- What is your feeder screw size? Oversized pellets can jam small screws.
- How much heat do you need per hour? Higher demand usually suits 8–10 mm.
Size is only one part of quality. Also check moisture, ash and calorific value on a test report, and make sure pellets arrive dry and with few fines.
Not sure which size you need?
Share your boiler make and capacity — we will recommend the right pellet.
