How many HP does a woodchipper need?

Tractors advertise engine HP (measured at the crankshaft). Chippers care about PTO HP(the HP that reaches the output shaft). Drivetrain losses — through the transmission, hydraulic pump, and PTO gearbox — reduce this by 10-15% on compact utility tractors and up to 20% on older machines.

A 35 HP engine tractor produces roughly 28-30 PTO HP. A 50 HP engine tractor produces ~42-43 PTO HP. Always size by PTO HP, not engine HP. Every chipper manufacturer lists PTO HP requirements for a reason — if you size by engine HP, you'll come up short on hardwood.

For a deeper comparison of PTO-driven vs self-powered chippers, see our PTO vs gas woodchipper guide. If you're not sure whether a PTO chipper is right for your setup, our sizing guide walks through the full decision tree.

The most common question we get: "I have a [tractor]. What chipper can I run?" Here are eight popular compact utility tractors and the chippers they pair with, based on published PTO HP and our testing experience.

• Kubota L2501(21.4 PTO HP) — Enough for 4-inch gravity-feed chippers like the Wallenstein BX36S or the MechMaxx BX42S. Tops out at 4-inch branches; don't push it into 6-inch territory.
• Kubota L3901(33.5 PTO HP) — Solidly in 6-inch chipper range. Runs the Wallenstein BX52S comfortably and can handle the Woodland Mills WC68 on softwood and green material.
• John Deere 3032E(25.2 PTO HP) — Pairs well with 4-to-5-inch chippers. The Woodland Mills WC46 is a natural match, and the Wallenstein BX52S works on lighter material.
• John Deere 3046R(37.3 PTO HP) — A versatile mid-range tractor. Runs 6-inch chippers with ease and can step up to an 8-inch gravity-feed like the Woodmaxx WM-8M on softwood. For regular hardwood 8-inch chipping, you'll want more HP.
• Mahindra 1533(27.5 PTO HP) — Good for 5-to-6-inch chippers. The Wallenstein BX52S is the sweet spot. Can run the Woodland Mills WC68 at minimum spec on green wood only.
• Massey Ferguson 1735M(29.4 PTO HP) — Right at the boundary between 6- and 8-inch territory. Comfortable on the Woodland Mills WC68. Can technically run the Woodmaxx WM-8H at its 30 PTO HP minimum, but you'll feel the limit.
• Kioti CK2620(22.4 PTO HP) — Similar to the L2501. Best paired with 4-inch chippers like the Wallenstein BX36S or MechMaxx BX42S. Don't exceed 4-inch capacity.
• New Holland WORKMASTER 35(28.1 PTO HP) — Solid 6-inch chipper tractor. The Wallenstein BX52S and Woodland Mills WC68 both work well. For the full 30 HP tractor chipper comparison, see our dedicated page.

Don't see your tractor? Check your owner's manual for PTO HP (not engine HP), then use the calculator above to match it to the right chipper capacity. Our best PTO woodchippers roundup lists every model by HP range.

Hydraulic-feed chippers draw 2-4 HP for the feed pump, so usable chipping HP is that much lower than rated PTO HP. On a 30 PTO HP tractor running an 8-inch hydraulic chipper like the Woodmaxx WM-8H, you're down to 26-28 HP at the flywheel — almost everything goes to chipping, leaving nothing in reserve.

Gravity-feed chippers like the Woodmaxx WM-8M or the Wallenstein BX72S don't have this overhead. Every PTO HP goes to the cutting disc or drum. That's why gravity-feed models can run on lower-HP tractors at the same branch diameter — but you're doing the feeding by hand, which is slower and more labor-intensive.

For large-scale clearing where speed matters, hydraulic feed is worth the HP overhead. For occasional property cleanup, gravity feed saves you from needing a bigger tractor. Our sizing guide covers when each feed type makes sense.

Dense seasoned hardwood (oak, hickory, maple) requires 25-40% more chipping HP than softwood (pine, spruce) or green hardwood. Most manufacturer specs are rated for seasoned hardwood — running below spec on softwood is usually fine.

Green wood — even green hardwood — chips significantly easier than dry seasoned wood because the moisture acts as a lubricant and the fibers haven't fully hardened. If you're cleaning up storm damage (almost always green), you can run closer to minimum HP. If you're clearing standing dead oak, size up.

For a self-powered option that handles hardwood without borrowing tractor HP, see the MechMaxx DCH7 (22 HP Honda GX) or its upgraded sibling the MechMaxx Power DCH7. Both are rated for 7-inch hardwood and don't touch your tractor's PTO. For more on when gas beats PTO, see the PTO vs gas comparison.

Running a chipper at the manufacturer's listed minimum HP works — the machine won't explode. But "works" and "works well" are different things. Here's what actually happens at minimum HP:

• Slower feed rate. The flywheel doesn't have the momentum to pull material through at full speed. You'll spend more time waiting per branch, especially on anything approaching the rated max diameter.
• Flywheel bogging on hardwood knots. Knots are the densest part of any branch. At minimum HP, a single large knot can slow or stall the flywheel. You'll hear the RPM drop and need to back the branch out and re-feed it at an angle.
• Increased blade wear. When the flywheel lacks momentum, blades spend more time in contact with each cut. More dwell time means more heat, which dulls edges faster. Read our blade sharpening guide for maintenance intervals.
• PTO shaft stress. When the chipper bogs, the PTO shaft absorbs shock loads. Shear bolts are designed to break before the shaft does, but repeated bogging wears the universal joints and splines faster. Over thousands of hours, this adds up.
• Tractor engine strain. Your tractor's engine is working at or near full load constantly. That's hard on cooling systems and increases fuel consumption by 20-30% compared to running at 70-80% load.

The practical advice: size 25-50% above the minimum for regular use. If you chip a few times a year after storms, minimum HP is fine. If you're clearing acres of brush monthly, invest in the headroom.

Gas engine chippers rate HP differently than PTO setups, and comparing them one-to-one is misleading. A gas chipper's engine drives the flywheel directly through a belt or clutch — no transmission losses. So 22 HP from a gas engine delivers roughly 20-21 HP to the cutting mechanism, while a 22 PTO HP tractor is already the net-of-losses number.

But not all gas engines are equal. Honda GX-series engines (used on the MechMaxx DCH7, MechMaxx Power DCH7, and Woodmaxx MX-8500GP) rate HP conservatively under SAE J1349. A 22 HP Honda GX690 genuinely makes 22 HP and holds it at sustained load. Generic Chinese engines often rate HP at peak (momentary burst), not sustained — a "22 HP" generic might only sustain 16-17 HP under continuous chipping load.

The practical difference is enormous. A Honda GX-powered 7-inch chipper will eat seasoned hardwood all day. A generic-engine 7-inch chipper rated at the same HP will bog on anything denser than green pine. When comparing gas chippers, look at the engine brand as closely as the HP number. The MechMaxx GS650 with its Kohler engine is another reliable option in the mid-range.

For the full breakdown on choosing between gas and PTO, see our PTO vs gas woodchipper guide.

Naturally-aspirated engines (both gas and diesel) lose roughly 3% of power per 1,000 feet of elevation above sea level. At 5,000 feet, that's a 15% reduction — a 50 HP engine makes about 42.5 HP. Turbocharged tractor engines compensate partially, but most compact utility tractors in the 25-50 HP range are naturally aspirated.

Extreme heat reduces power too. At 100°F, expect 2-4% less HP than at 60°F. These losses stack with altitude. If you're running a Wallenstein BX72S at 4,000 feet in July, your "40 HP" tractor might deliver 32-33 PTO HP — enough for the chipper's minimum but not enough for comfortable hardwood chipping.

If you're above 3,000 feet, add 10-15% to the HP numbers in our sizing tables. The calculator at the top of this page does not currently account for altitude — use it as a baseline and add the altitude adjustment manually.