Calculator
One-third rule: how low to cut today
Cutting off too much at once stresses the grass. Enter how long the grass is now and the height you want, and the calculator spreads the work over several cuts.
In short
The RHS advises removing no more than one third of the grass height at any one cut. Lowest cut today = current height x 2/3. One inch is 25.4 mm.
Work out today's cut
Lowest cut today
50 mm (1.97 in)
Removes at most 25 mm (0.98 in)
Cuts to reach the target
2
- Cut 1:50 mm (1.97 in)
- Cut 2:35 mm (1.38 in)
Based on RHS guidance: remove no more than one third of the grass height at any one cut. Type decimals with a point.
Typical cutting heights
| Lawn | Summer height |
|---|---|
| Fine ornamental lawn | 13 to 25 mm (0.5 to 1 in) |
| Everyday family lawn | 25 to 40 mm (1 to 1.6 in) |
| Spring, autumn, dry spells or shade | Raise by about 10 mm (0.4 in) |