A cubic metre explained

A cubic metre of firewood is the industry standard for measuring the volume of a "load" of firewood.
It is a unit of volume and not weight, as the weight of the wood contained in a cubic metre will vary significantly with species and moisture content.
If you were to build a box of internal dimensions 1 metre x 1 metre x 1 metre then throw in firewood upto the brim then this would be a cubic metre of firewood.  Therefore it is a measure of the loose volume of the firewood, and you can expect its volume to decrease by around one third when stacked.

A better way to visualize what a cubic metre looks like is to imagine 3 standard washing machines, that would equal approximately one cubic metre of loose firewood.

850mm High x 595mm Deep x 600mm Wide
= 0.303 x 3 = 0.91 Of a cubic metre.

Please note when logs are stacked neatly there will be less volume due to less air space.

Below is a stacked cubic metre of firewood logs

Below is tipped cubic metre of 250mm (10") long firewood.

A cubic metre is not a builder's one tonne dumpy bag! That is less than 0.75 m3, and what's more, a one tonne dumpy bag does not hold one tonne of wood, more like 200kg (1/5th tonne) assuming the wood is well seasoned and ready to burn. If it is heavier than that, it is too wet.

Typical builders bag on the left compared to a cubic metre bag on the right.