Grass Cutting Height Calculator
Find the perfect mowing height for your lawn based on grass type, season, and conditions.
Enter Your Lawn Details
- Never cut more than 1/3 of the grass blade height at once
- Keep mower blades sharp for clean cuts that heal quickly
- Vary mowing direction to prevent soil compaction
- Leave grass clippings to return nutrients to soil
- Mow when grass is dry for better results
How short you cut your grass matters more than almost anything else you do to a lawn — more than feeding, more than watering. Most lawns are cut too short. The chart below gives the right height for each common grass type, and the calculator above works it out for your grass and the time of year.
Mowing height chart by grass type
Heights are for the cut blade, measured on a flat surface. The “never below” column matters as much as the range: going under it removes more leaf than the plant can replace, and that is what turns a lawn thin and weedy.
| Grass type | Season | Recommended height | Never below |
|---|---|---|---|
| Kentucky bluegrass | Cool | 2.5 – 3.5 in | 2 in |
| Tall fescue | Cool | 3 – 4 in | 2.5 in |
| Fine fescue | Cool | 2.5 – 4 in | 2 in |
| Perennial ryegrass | Cool | 2 – 3 in | 1.5 in |
| Creeping bentgrass | Cool | 0.5 – 1 in | 0.5 in |
| Bermuda (common) | Warm | 1 – 2 in | 0.75 in |
| Bermuda (hybrid) | Warm | 0.5 – 1.5 in | 0.5 in |
| Zoysia | Warm | 1 – 2.5 in | 0.75 in |
| St. Augustine | Warm | 2.5 – 4 in | 2 in |
| Centipede | Warm | 1.5 – 2 in | 1 in |
| Bahia | Warm | 2.5 – 4 in | 2 in |
| Buffalograss | Warm | 2 – 3 in | can be left unmown |
These are the ranges used across most regional guidance. Local extension services sometimes narrow them for a particular climate, so if yours publishes a figure for your county, prefer that one.
How short can you cut grass?
Shorter than the “never below” figure and you are scalping. A grass plant feeds through its leaves, and its roots grow roughly as deep as the blade is tall. Take too much leaf and it has to rebuild using stored energy, which means it puts nothing into roots. Shallow roots dry out faster, so the lawn browns sooner in heat, needs more water, and leaves bare soil where weed seed can get light.
The opposite mistake is rarer and much less costly. Grass cut an inch too long looks slightly shaggy. Grass cut an inch too short can take a season to recover.
The one-third rule
Never remove more than a third of the blade in one cut. Going from four inches to two in a single pass shocks the plant, and it is the usual reason a lawn yellows a day or two after mowing. If it has got away from you, bring it down in stages a few days apart rather than all at once.
This rule, not the calendar, is what sets your mowing frequency — twice a week in spring growth, barely at all in high summer. Our guide to how often to mow works through the schedule, and the best cutting height for a healthy lawn covers the reasoning behind the numbers above.
Adjusting height through the season
- Spring — start at the lower end of the range for the first cut or two to clear winter debris, then raise it.
- Summer — raise to the top of the range. More leaf shades the soil, holds moisture and protects the crown through heat.
- Autumn — back to mid-range as growth slows.
- Before winter — a notch lower than mid-range so the grass does not mat down under wet leaves. A notch, not a scalping.
Your mower is probably not cutting where you think
Deck settings are notional. The number on the lever is measured to the bottom of the blade on flat ground, and worn wheels, soft tyres or a bent deck easily put the real cut half an inch away from it. It is worth measuring once — how to measure your mower’s cutting height explains how.
A blunt blade undoes the whole exercise regardless of height: it tears rather than cuts, and the frayed tips brown off within a day. Sharpening the blade yourself is straightforward, and mowing too short with a dull blade is one of the most common lawn care mistakes.