A European standard for wood fuel pellets was introduced in 2011 EN 14961-2 the specifications for premium wood pellets are:

Particle size: 6mm to 8mm for domestic and small scale systems, 10-12 mm  for larger systems
Moisture content: less than 10%
Calorific value: less than 4.7kWh/kg
Ash content: less than 1% (low), less than 3% (standard) or less than 6% (high); to be clearly labelled
Bulk density: less than 600 kg/m
Sulfur content: less than 300 ppm
Chlorine: less than: 800ppm
Only additives: lignin and trace amounts of vegetable oil as a die lubricant
Mechanical durability of pellets is specified in EN 335, with determination by technical standard CEN/TS 15210-1:2005.

The CEN/TC 355 standards include detailed specifications for sampling and testing biomass fuel.

ENplus wood pellet certification
ENplus is a unifying wood pellet quality assurance system based on the EN 14961-2 standard for wood pellets. It was agreed upon by the European Pellet Council in January 2011. HETAS is a certification body.