Every stump grinder gets a score from 0 to 100% built from seven factors, which maps onto the 5-point rating shown on the site (a 0% score would be 1.5 stars; a perfect score, 5). Each factor is scored against fixed reference points, not against the other products in the list, so adding a new model never moves another model’s rating. Walk-behind and PTO grinders are grouped and scored on separate scales where they differ.
| Factor | Measures | Weight |
|---|---|---|
| Price | price of the grinder | 25% |
| Depth | deepest cut below grade | 20% |
| Height or wheel | cutting height above grade (walk-behind) or cutter wheel diameter (PTO) | 10% |
| Power | engine displacement (walk-behind) or largest tractor allowed (PTO) | 10% |
| Teeth | number of teeth on the cutter wheel | 10% |
| Features | electric start, tow bar and swing (walk-behind) or slip clutch, hydraulic swing and stand (PTO) | 15% |
| Warranty | warranty length | 10% |
Where the numbers come from
Depth, cutting height, wheel size, teeth, engine, tractor range, features and warranty come from the maker’s product page, spec sheet or owner’s manual, the maker’s own copy on a retail listing, or the product page of a dealer that sells it. Where two of those disagree, the lower depth or the manual’s figure is used and the product page says so. Prices are checked at Amazon, the maker’s own store and other stores that sell the exact model new, and the lowest price at a store the page links to is used.
The factors
Price is the current price, on a log scale, so halving the price always counts the same. For walk-behind grinders, $5,000 scores zero and $1,100 full marks. For PTO grinders, $5,000 scores zero and $1,400 full marks.
Depth is how far below grade the grinder cuts. For walk-behind grinders, 6 in scores zero and 11 in full marks. For PTO grinders, 3 in scores zero and 10 in full marks.
Height or wheel is the cutting height above grade for walk-behind grinders: 8 in scores zero and 16 in full marks. Makers rarely publish it for PTO grinders, so for them it’s the cutter wheel diameter instead: 20 in scores zero and 30 in full marks.
Power is the engine displacement for walk-behind grinders: 200 cc scores zero and 430 cc full marks. For PTO grinders it’s the largest tractor the maker lists, a sign of how much power the gearbox and shaft are built to take: 30 hp scores zero and 100 hp full marks.
Teeth is the number of cutting teeth on the wheel. For walk-behind grinders, 4 scores zero and 12 full marks. PTO wheels carry more, smaller teeth: 10 scores zero and 44 full marks.
Features for walk-behind grinders is 35% for electric start, 35% for an included tow bar, and 30% for a chassis or head that swings across the stump while the wheels stay put. For PTO grinders it’s 50% for a slip clutch on the PTO shaft, 30% for hydraulic swing controlled from the seat, and 20% for a stand or legs to park it at hitch height.
Warranty is the maker’s warranty on the machine, not the engine alone: no warranty scores zero and 3 years full marks.
What isn’t scored
Engine make and horsepower, self-propelled drive, hitch category, weight, cutting width per pass, tooth type, wheel brakes, debris guards and release date are listed but not scored. A separate engine warranty, such as Kohler’s, is noted on the product page but not counted.
Missing data
If a figure isn’t published, that factor gets the neutral middle score (50) and the product page marks it as estimated. Features score neutral only when none of the three is published; a feature the maker doesn’t mention otherwise counts as absent. The exception is warranty: a maker that doesn’t publish one gets no warranty counted, so that factor scores zero and is marked estimated.
Ties and discontinued models
Products are ranked by score within each group. Discontinued models stay listed but rank below every current model and can be hidden with the “Hide discontinued” filter.