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Lawn Mowing Height Calculator — Ideal Cut Height
Find the ideal mowing height for your grass type and season.
Fine/ornamental lawns take the lowest cuts (RHS 6-13 mm); general and hard-wearing family lawns are kept taller (25-50 mm) to better tolerate wear.
Cut lower in summer when growth is strongest; raise the height in spring/autumn transitions and over winter to protect the grass crown.
Higher-traffic lawns (children/pets) are mown about 5 mm taller so the longer leaf better withstands wear; decorative low-use lawns can go slightly shorter.
Optional: current height to apply the one-third rule (default 0 = skip)
Add mm for shaded areas — longer blades capture more light (default 0)
Optional: enter lawn size to estimate mowing duration (default 0)
How We Calculate This
Mowing height recommendations are based on grass type and season, following RHS and amenity grassland guidelines.
General purpose: 25-40 mm. Fine/ornamental: 6-13 mm (RHS band). Hard-wearing: 30-50 mm. Wildflower: 50-100 mm.
Heights are adjusted seasonally — lower in summer when growth is active, higher in spring/autumn transitions and winter.
Frequently Asked Questions
Never remove more than one-third of the grass blade length in a single mow. Cutting too short stresses the grass and promotes weeds and moss.
Yes. Raise the mower by 10-15 mm in shaded areas. Longer blades capture more light and produce healthier grass in low-light conditions.
Raise to 40-50 mm for the last few cuts of the year. This protects the crown of the grass plant through winter.
Yes. Mowing too short weakens grass and encourages moss. Maintaining the correct height for your grass type helps grass outcompete moss.
During active growth (June-August) most lawns need mowing about twice a week to keep the cut within the one-third rule. As growth slows in autumn, drop to every 10-14 days, and in winter only mow on mild, dry days. Always mow regularly enough that you remove just a small amount each time.
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Last updated: February 2026
All calculations are estimates based on standard gardening guidelines. Results may vary with soil conditions, climate, and plant varieties.