Hardwood is denser than softwood so has a higher heat content or calorific value. Typically, the heat content of softwood is little more than half as much as hardwood by volume.
- Typical heat content of hardwood 2300kWh/m³ (stacked)
- Typical heat content of softwood 1,300kWh/m³ (stacked)
Broadly speaking, around twice as many softwood logs as hardwood logs may be required to achieve the same heat output so more frequent refueling will be necessary when burning softwood.
On the other hand, softwood tends to light more easily than hardwood and burns faster due to its resin content.