It is approximately as accurate with smaller logs as with larger logs. To measure moisture content in firewood. Air space can actually be as high as 40 percent but usually averages 25 percent.
Then measure the length of the log in feet.
Hold the tape measure at the end of one of the 8-foot logs and mark the log every 16 inches with the axe blade. Typically logs are measured in 2-foot intervals eg 8 10 12 etc. Steady the blade with the other free hand. Measure the length of the log.