Quick answer
For most UK households, a 5 to 7 tonne electric log splitter is plenty. If you burn seasoned softwood and average hardwood up to roughly 250mm in diameter, a 7 tonne mains machine will cover almost everything you put through it.
Go up to 8 to 10 tonne (ideally a two-speed model) only if you regularly split big, knotty or fully seasoned dense hardwood like beech and oak. Step up to petrol or a tractor-driven PTO machine when the rounds are too heavy to lift onto a bed and you are processing real volume.
One honest point before the numbers: there is no standard, regulated test for a log splitter’s “ton” rating. Manufacturers calculate it themselves, usually from the ram bore area multiplied by the maximum hydraulic pressure. That is a theoretical peak the machine rarely hits under real load, so treat every quoted tonnage as optimistic and leave yourself some headroom.
Tonnage by wood type and log diameter
Use this as a guide, not gospel. UK manufacturer guides vary on the exact figures, and the same log can split easily one day and fight you the next depending on its grain.
| Log diameter | Softwood / small seasoned | Dense seasoned hardwood / knotty |
|---|---|---|
| up to ~15 cm | 4 t | 4 to 5 t |
| ~20 to 25 cm | 5 t | 7 t |
| ~25 to 30 cm | 7 t | 8 to 10 t |
| ~30 to 40 cm | 7 to 10 t (if you can lift it) | 10 t+ / petrol / vertical |
| 40 cm+ / elm / big and knotty | petrol 14 t+ | petrol or PTO 16 to 22 t+, vertical |
The pattern is simple. Diameter and wood density drive the headline number you need. Knots and twisted grain are what actually defeat machines, and no chart can fully predict those.
The four things that decide the force you need
In rough order of how much they matter:
1. Diameter. This is the biggest single factor. A wider round needs more force to push the wedge through, and it also gives knots and grain more room to fight back. Most domestic electric splitters are diameter-limited above all else.
2. Species and density. Soft, straight-grained species split easily: most conifers, plus willow and poplar. Dense UK hardwoods need more: ash and birch are still fairly cooperative, while beech and oak get stubborn as they dry. Elm is in a class of its own.
3. Moisture (green versus seasoned). This one surprises people, and most US-written guides get it backwards. See the section below.
4. Grain defects. Knots, forks where a branch met the trunk, and interlocked grain. A modest log with a knot through the middle can stop a 7 tonne machine dead when a clean log twice the size goes through without complaint.
Green versus seasoned: the bit US guides get wrong
Plenty of American sources tell you green wood needs “about 10 more tons.” For UK firewood species, that is misleading.
Green wood is generally easier to split than the same species fully seasoned. The fibres have not dried and hardened, and the log has not case-hardened on the outside. Forest Master put it plainly: a 7 tonne electric will split just about every wood you can put in it, so long as the wood is still green.
The nuance: very large green rounds of oak or elm are still brutal, but that is down to their size and grain, not the moisture. A big green round needs force because it is big, not because green wood is somehow harder. So if you have the choice, split your dense hardwood while it is still fresh and let the halves season faster anyway. Smaller pieces dry quicker, so you win twice.
Diameter and length set your real limit
Two specs on any machine matter more than the headline tonnage: maximum log diameter and maximum log length.
A 4 tonne electric typically takes logs around 250mm in diameter and 370mm long. A good 7 tonne unit stretches to roughly 300 to 400mm in diameter and 430 to 520mm long depending on the model. If your logs are longer than the bed, you cannot split them, however much force the ram has.
This is also why “make the log smaller” is the honest fix for a stalled domestic machine. Cut shorter, or split the round in from the edge rather than driving the wedge through the dead centre, and you ask far less of the machine.
Knots, forks and elm
If a log is going to beat a domestic splitter, it is usually one of three things:
- Elm. Its interlocked, twisting grain is the genuine nightmare of UK firewood. Even seasoned and modestly sized, elm can refuse to split cleanly on machines that handle everything else.
- Knotty or forked beech and oak. Where a branch met the trunk, the grain swirls. These spots resist the wedge and can stop a machine that splits the straight sections of the same log easily.
- Fibrous fruit-tree wood. Apple, pear and similar are dense and stringy, and they hang on even after the wedge has gone through.
For this kind of wood, a two-speed machine helps. So does a clever blade design: Forest Master’s DuoCut blade splits the log from both ends, which gives knots a second angle of attack. But honestly, the occasional piece is best dealt with by reducing its size, attacking from the edge, or accepting that an axe, froe or grenade wedge will finish what the machine started.
Recommendations by household
Occasional weekend burner. You light the stove at weekends and on cold evenings, and you burn bought softwood or small seasoned logs up to about 250mm. A 4 to 5 tonne electric is enough. The Handy THLS-4G (4 tonne, 1500W, two-handed operation) and the Titan TTB762LSP from Screwfix (4 tonne, brushless) are honest entry-level domestic machines. Buy one knowing it will stall on big or knotty hardwood. That is the deal at this size.
Regular winter burner. You heat through the season with mixed firewood, including occasional UK hardwood like ash, birch and cherry up to around 300mm. This is the domestic sweet spot, and a 7 tonne electric is the answer. The Forest Master FM10T-7 (2200W, takes logs up to 400mm in diameter, with the DuoCut blade) and the Titan Pro 7 Ton are solid, widely sold UK choices. Both handle the bulk of stove firewood; both are still diameter-limited, so very large dry oak or elm can defeat them.
Processing your own felled hardwood. You are cutting up beech, oak or fruit-tree wood from your own land and the rounds are bigger and tougher. Move to an 8 to 10 tonne two-speed machine. The Forest Master FM16D is an 8 tonne two-speed with the DuoCut blade aimed at fibrous and seasoned hardwood. The DuoCut splits from both ends, which the maker frames as effectively doubling its splitting capacity, so size your expectations to a true 8 tonne ram with a clever cutting head rather than to the doubled figure.
When the rounds are too heavy to lift safely onto a horizontal bed, that is a sign to go petrol or vertical, not just to buy more tonnage. More on that below.
When you outgrow mains electric
A 13A socket and a horizontal bed have natural limits. You cross into petrol when you want bigger diameters, faster cycles and freedom from the mains. UK prosumer petrol machines run roughly 14 to 22 tonne. The Forest Master FM22VPT, for example, uses a two-stage pump (about 14 tonne fast, 22 tonne heavy), takes logs up to 1.1 metres, and has a built-in lifter so you are not hoisting big rounds by hand. That last point matters as much as the force.
You cross into PTO (tractor-driven) for the highest force, typically 10 to 27 tonne, run straight off the tractor engine. It is the cheapest way to big force, but only if you already own a tractor. UK professionals commonly run 13 to 18 tonne PTO machines. For a household with a stove, it is pointless.
Vertical splitting is a safety decision too
Once a round is too heavy to lift onto a horizontal bed, roughly above 300 to 400mm of dense wood, a vertical splitter lets you roll the log into position instead of lifting it. That is a back-safety issue as much as a throughput one, and vertical machines tend to carry higher tonnage anyway. If you find yourself manhandling rounds onto a bench, the right upgrade may be the layout, not just the force.
Tonnage is not the only number that matters
A high-tonnage machine with a slow cycle produces less firewood per hour than a faster mid-tonnage one. Force and speed trade off against each other in a single-stage pump. Two-stage pumps are the UK answer: a fast, low-force stroke to close the gap, then a slow, high-force stroke for the actual split. If you are processing volume, cycle time deserves as much attention as the headline tonnage.
For more on picking the right mains machine, see our guide to the best electric log splitter in the UK, and the full log splitters hub for everything else. If yours has stopped mid-job, our won’t start or ram won’t return page covers the common causes.
We may earn a small commission from links on this page; see our affiliate disclosure for the details. When you have settled on a size, you can Check price on Amazon for current options.
Frequently asked questions
What tonnage do I need to split oak, beech or ash? For seasoned oak and beech up to about 250 to 300mm, a 7 tonne electric handles most of it, but big, dry or knotty pieces want 8 to 10 tonne. Ash is friendlier and splits well even on a 5 to 7 tonne machine. Split dense hardwood while it is still green if you can, as it is easier then and seasons faster once halved.
Is a 5 tonne or 7 tonne electric log splitter enough? For the vast majority of UK households, yes. A 5 tonne machine suits softwood and small seasoned logs; 7 tonne is the domestic sweet spot and covers mixed firewood and occasional hardwood up to around 300mm. Most homeowners never need more.
How big a log can a 7 tonne splitter handle? Roughly 300 to 400mm in diameter and 430 to 520mm long, depending on the model, and that is the limit that bites first, not the tonnage. Beyond those dimensions you cannot fit or split the log even if the ram has the force.
Do I need more tonnage for green wood or seasoned wood? Green wood is generally easier to split than the same species fully seasoned, so you do not need more force for it. The exception is sheer size: a big green round needs force because it is big, not because green wood is harder. Ignore the common claim that green wood needs ten more tonnes; it does not hold for UK firewood.
What is the hardest wood to split? Elm, because of its interlocked, twisting grain. After that, knotty or forked beech and oak where a branch met the trunk, and fibrous fruit-tree wood like apple and pear.
Why won’t my log splitter split this log? Almost always one of three things: the log is too big in diameter for the machine, there is a knot or fork in the way, or the grain is twisted. The fix is to reduce the log size, split in from the edge rather than the centre, or set that piece aside for an axe. Never override the relief valve or force a stalled machine.
Are log splitter tonnage ratings accurate? No, they run optimistic. There is no standard, regulated test, so manufacturers calculate the figure themselves from bore area and maximum pressure, which is a peak the machine rarely delivers under load. A unit advertised at a high tonnage may compute to far less at typical working pressure, so always leave headroom.
Electric, petrol or PTO: which do I need? Electric (4 to 8 tonne) suits almost every household with a stove. Petrol (14 to 22 tonne) is for bigger diameters, faster cycles and working away from a socket. PTO (10 to 27 tonne) makes sense only if you already own a tractor and are processing serious volume.
Do I need a vertical log splitter? Only if your rounds are too heavy to lift safely onto a horizontal bed, roughly above 300 to 400mm of dense wood. A vertical machine lets you roll the log in instead of lifting it, which protects your back and usually carries more tonnage too.
Can a log splitter split knotty wood? A good two-speed or DuoCut-style machine handles most knots, but the occasional bad piece will beat any domestic splitter. Reduce its size, attack from the edge, or finish it with an axe or grenade wedge. That is normal, not a fault with the machine.