These firewood BTU charts compare the heat energy ratings and weight of common firewood species. You may notice that as the dry weight per cord increases, so does the BTU rating. Wood has close to the same BTU per dry pound regardless of species. The more dense a wood is, the more weight and BTU it will have. The exception to this is softwoods, which have slightly more BTU per pound than hardwoods. This is because of the resins in softwoods, which have more energy than wood fiber. But this difference is only slight and the dense hardwoods are so much more dense than softwoods, that they will still produce much more heat energy.