Slope is the specification people most often get wrong, and the one that ruins the experience when they do. A mower that can’t climb your bank will get stuck on it — not once, but every single week.
Percentages, not degrees
Manufacturers quote slope as a percentage. A 25% slope rises 25cm over one metre travelled. That sounds gentle written down, and it is — but 45% is a bank you would think twice about pushing a petrol mower up, and it’s roughly 24 degrees.
To measure yours: rest a straight plank on the slope, put a spirit level on it, raise the downhill end until level, and measure the gap to the ground. Gap in cm ÷ plank length in cm × 100 = your percentage.
What the numbers mean in practice
| Rating | What it handles |
|---|---|
| 25% | Gently undulating lawns. Most entry-level machines. |
| 35% | A noticeable slope on part of the garden. |
| 45% | A genuine bank. Fewer models, and they cost more. |
| 70% | Steep terracing and embankments. Specialist machines. |
Three things the rating doesn’t tell you
Wet grass changes everything. Slope ratings assume reasonable traction. A 35%-rated mower on a 30% slope will still slip after heavy rain. If your lawn holds moisture, buy a size of slope capability above what you measured.
Slopes at the boundary are worse than slopes in the middle. A mower turning on a gradient near the edge has less room to recover. If your steepest ground is at the lawn’s edge, err upward.
Wheel design matters as much as the rating. Deep-tread or spiked wheels hold a wet bank far better than smooth ones. Two mowers with the same quoted figure can behave very differently.
Not sure what you’ve got? Send us a photo of the slope — we’ll tell you what will cope.