Gas and electric log splitters are measured in terms of driving force, which is the maximum amount of force the wedge can exert against the log. Naturally, the higher the tons of driving force, the stronger the tool, and the larger the logs you can split. As a general rule, gas log splitters can have much higher driving force than electric models, but the main consideration is the typical size of logs you’ll be splitting. For many people, a low to medium driving force will be sufficient. You’ll also want to consider whether you’ll generally be splitting new, green wood, or older, “seasoned” wood. Green wood requires more driving force than seasoned wood to split cleanly.  As a rule of thumb:  Six-inch logs need 4 to 5 tons of driving force. Twelve-inch seasoned logs require a 7 to 10 ton splitter, while 12-inch green logs may need up to 16 tons of driving force. Eighteen-inch seasoned logs need at least 20 tons of driving force, while a green 18-inch log can require as much as 30 tons of force. A 24-inch green log requires up to 25 tons of pressure, while a green 24-inch log might need over 30 tons of driving pressure.