Log Splitter Tonnage Calculator

Log splitters are sold by tons of splitting force, from 4-ton electric models to 37-ton gas machines. The right number depends on three things: how hard your wood is to split, how big your biggest rounds are, and whether those rounds are straight-grained or full of knots. Enter yours below to get a tonnage range to shop for.

How the calculation works

Species factor. Each species in our species table has an ease-of-splitting rating from 1 (stringy and interlocked, like elm and sycamore) to 5 (splits clean, like ash and cedar). The rating sets a force per inch of diameter: 0.8 tons per inch for a 5, 1.0 for a 4, 1.15 for a 3, 1.3 for a 2 and 1.5 for a 1.
Diameter. Estimated tons = largest round diameter (in) x the species factor.
Condition and grain. Multiply by 1.1 for green wood (wet fibers in stringy species hold together) or 0.9 for frozen wood, and by 1.2 for some knots or 1.4 for knotty, crotch or twisted grain.
Range to shop for. The low end is the estimate rounded up to a common splitter size. The high end adds 25% headroom for the odd tough round, rounded up the same way. The minimum is 4 tons.

Worked example

You split seasoned, straight-grained oak, and the biggest rounds are 18 in across. Oak rates 4 for ease of splitting, so 18 x 1.0 = 18 tons. Rounded up to common sizes, that is 20 to 25 tons: a mid-size gas splitter.

Change the wood to green, knotty elm at the same 18 in: 18 x 1.5 x 1.1 x 1.4 = 41.6 tons, which is beyond most consumer splitters. In practice, that round is a job for a 34-ton-plus vertical splitter, or for cutting it into smaller pieces with a chainsaw first. Straight ash at 18 in comes out at 14.4 tons, so a 16 to 20 ton splitter is plenty.

Assumptions and limits

This is a rule of thumb for planning, not an engineering calculation. Manufacturer tonnage is a calculated figure from pump pressure and cylinder size rather than a measured split, and cycle time, wedge shape and log fit matter as much as tons. A splitter also has to physically take your wood: check its maximum log length and diameter. If most of your wood is small and only a few rounds are huge, a smaller splitter plus a maul and wedges for the big ones can be the better buy.

Log splitter safety

One operator only, with hands well clear of the wedge and the ram. Wear eye protection and gloves, set the splitter on stable, level ground, and keep kids and pets away from the work area. Run gas splitters outdoors only, and never reach in to clear a jammed log while the ram can move. Read our Safety Disclaimer.

Frequently Asked Questions

How many tons of log splitter do I need?

For straight hardwood up to about 12 in, a 7 to 10 ton electric splitter is usually enough. For hardwood rounds of 18 to 24 in, most people need 20 to 27 tons. For knotty, stringy wood such as elm or sycamore, or rounds over 24 in, look at 30 tons or more. Use the calculator above with your own wood.

Is a bigger tonnage splitter always better?

No. More tons usually mean a heavier, louder, more expensive gas machine, and often a slower cycle time. If your wood is small and straight, a lighter splitter with a faster cycle splits more wood per hour.

Is green or seasoned wood easier to split?

It depends on the species. Many straight-grained hardwoods such as oak and ash split well green. Stringy woods such as elm, sycamore and cottonwood are often easier once dry or frozen. The calculator adds a modest factor for green wood to cover the stringy cases.

Can a 5 ton electric splitter split oak?

Small, straight, seasoned oak up to about 8 to 10 in, yes. Larger or knotty oak rounds will often stall a 5 ton unit. Check the splitter’s maximum diameter as well as its tonnage.

What else matters besides tonnage?

Cycle time (how many seconds the ram takes to go out and back), maximum log length and diameter, horizontal or vertical operation for heavy rounds, a log lift, wedge type, and whether the engine or motor suits where you split. Our guide on how many tons of log splitter you need covers each one.

Log splitter guides

Next: browse all log splitter guides or compare woods in the species table.