Mowers
What Size Mower for a Half Acre With Hills? Deck, Drive and Safety
Quick answer
A half acre with hills needs a 21 to 30 inch rear-wheel-drive self-propelled walk-behind. A 21 inch deck takes about 1 hr 25 min on hilly ground, and the 25 inch Greenworks 80V 25 in. Self-Propelled Mower Kit about 1 hr 12 min. Mow across slopes, not up and down, and use a trimmer or slope-rated robot on steep banks.
On a flat half acre, a small rider is a reasonable upgrade. On a hilly half acre it usually is not. A rider's weight sits high, sloped half-acre lots tend to have short, steep grades where riders are least stable, and the time saved shrinks once you slow down for the slope. A wide rear-wheel-drive walk-behind is the better tool, and it keeps you in control.
First, find out how steep your slopes are. The table below shows how to measure and what each grade means for a half acre.
On this page
- How long does it take to mow a hilly half acre?
- How do I measure how steep my yard is?
- What is the best mower for a half acre with hills?
- Does mowing across a slope take longer than up and down?
- Will a battery mower last on a hilly half acre?
- What if part of my half acre is too steep for any mower?
- Which mowers suit a hilly half acre?
How long does it take to mow a hilly half acre?
| Mower | Time per mow | Fit for this lawn |
|---|---|---|
| 21 in walk-behind | 1 hr 25 min | Recommended |
| 30 in rider | 40 min | Recommended |
| 42 in lawn tractor | 28 min | Larger than needed |
| 46 in lawn tractor | 26 min | Larger than needed |
| 48 in zero-turn | 17 min | Zero-turn: not advised on slopes |
| 54 in zero-turn | 15 min | Zero-turn: not advised on slopes |
| 60 in zero-turn | 14 min | Zero-turn: not advised on slopes |
Recommended deck: 21 to 30 inches, rear-wheel-drive self-propelled walk-behind. Times assume typical cutting speeds (3 mph walk-behind, 4.5 mph tractor, 6.5 mph zero-turn), a 15 percent overlap and 65 percent efficiency for this terrain.
How do I measure how steep my yard is?
Use a 48 inch level. Rest the uphill end on the ground, lift the downhill end until it reads level, and measure the gap. Percent slope is the gap in inches divided by 48, times 100. Measure the steepest part of each slope, not the average.
| Gap under a 48 in level | Slope | Degrees | Half-acre approach |
|---|---|---|---|
| 2.4 in | 5 percent | 2.9 | Any walk-behind; a rider is fine within its manual |
| 4.8 in | 10 percent | 5.7 | RWD walk-behind across the slope |
| 7.2 in | 15 percent | 8.5 | RWD walk-behind across; shorten passes and slow the drive |
| 9.6 in | 20 percent | 11.3 | Walk-behind across only with firm, dry footing |
| 14.4 in | 30 percent | 16.7 | Trimmer, or a robot such as the Mammotion LUBA 2 AWD 3000X Robot Mower (80 percent rating) |
Degrees = arctangent of percent / 100. A 10 percent slope rises 12 inches over 10 feet, and a 20 percent slope rises 24 inches.
What is the best mower for a half acre with hills?
A rear-wheel-drive self-propelled mower with some extra width. The Greenworks 80V 25 in. Self-Propelled Mower Kit pairs rear drive with a 25 inch deck and a 0.75 acre rating, which leaves headroom for climbing. The SENIX 22 in. Variable Speed RWD Self-Propelled Gas Mower, 201cc is the gas option, with variable-speed rear drive and a four-wheel height adjuster. If you bag, the PowerSmart 22 in. High Wheel Self-Propelled Gas Mower, 170cc has 10 inch rear wheels and a rear bag intended for inclines. A full bag adds weight at the back, so empty it before tackling the steepest pass.
A 30 inch walk-behind such as the Toro 60V MAX 30 in. eTimeMaster Personal Pace Mower (Tool Only) cuts the time to about 60 minutes, but it is heavy to hold on a side slope. It suits the gentler part of a hilly lot better than the steep part. The table's 30 inch figure of 40 minutes assumes a rider, which we do not recommend here.
Does mowing across a slope take longer than up and down?
Yes. Cross-slope passes drift downhill, so you overlap more, and every turn on a grade is slower. The computed tables account for this with 65 percent efficiency on hills versus 80 percent on flat ground, which works out to about 23 percent more time. On a half acre, that is the difference between 1 hr 9 min and 1 hr 25 min with a 21 inch mower. Mowing up and down with a walk-behind might look faster, but it puts you below the mower on the downhill pass, so do not do it.
Will a battery mower last on a hilly half acre?
Plan for two batteries. Battery ratings are set on typical grass, and climbing takes more energy than mowing flat ground, so a battery rated for exactly half an acre will likely fall short here. A 25 inch mower rated for 0.75 acre with one spare pack is a sensible setup, and the battery mower runtime calculator lets you model it.
What if part of my half acre is too steep for any mower?
Stop mowing it. A string trimmer like the gas Husqvarna 130L 28cc Straight Shaft Gas String Trimmer handles a bank from the top, and ornamental grasses or groundcover end the job for good. A slope-rated robot is the third option: the WORX Landroid Vision Cloud WR342 4WD Robot Mower is rated for 84 percent slopes on half an acre, and the Mammotion LUBA 3 AWD 5000 Robot Mower for 80 percent on 1.25 acres. See the best robot mowers for hills.
Which mowers suit a hilly half acre?
Greenworks 80V 25 in. Self-Propelled Mower Kit
$717.27A 25-inch deck with a brushless motor and rear-wheel drive, rated to cut up to three quarters of an acre on the included 4.0Ah battery.
Best for: Open lawns approaching an acre
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SENIX 22 in. Variable Speed RWD Self-Propelled Gas Mower, 201cc
$509.99Variable-speed rear-wheel drive and a single-handle, four-wheel synchronized height adjuster sit on a 201cc, 22-inch 3-in-1 platform with a 2-year warranty.
Best for: Larger yards where you want to set your own pace
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Greenworks 80V 21 in. Self-Propelled Mower Kit
$479.99Rear-wheel drive with variable speed and an 80V brushless motor, rated to cut up to half an acre on the included 4.0Ah battery with a 4-year tool and battery warranty.
Best for: Half-acre lawns with some slope
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PowerSmart 22 in. High Wheel Self-Propelled Gas Mower, 170cc
$347.98A 22-inch all-steel deck, 10-inch rear wheels and single-speed rear-wheel drive suit bagging on inclines, with a 1.4-bushel rear bag.
Best for: Bagging clippings on sloped lawns
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WORX Landroid Vision Cloud WR342 4WD Robot Mower
$2,069.99Cloud RTK needs no local antenna, 4WD climbs slopes up to 84%, and the Cut-to-Zero offset blade trims closer to borders, rated for 1/2 acre.
Best for: Hilly half-acre yards
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Mammotion LUBA 2 AWD 3000X Robot Mower
$1,998.00Four-wheel drive climbs 80% slopes, RTK plus AI vision handles mapping and edge cutting, and a 15.8-inch dual-blade disc covers up to 0.75 acre, with 4G tracking.
Best for: Sloped lawns up to 3/4 acre
Check price on AmazonHow we chose
We did not test these products in person. Picks are researched from manufacturer specifications and owner manuals, engine and safety certifications where they apply, warranty terms, public recall records, and the recurring themes in verified owner reviews. We favor established brands with large review counts and parts support, match each pick to a real yard size or task, and place it in the tier where its price and capability actually belong.
Frequently asked questions
Is a riding mower safe for a half acre with hills?
It depends on how steep the slopes are and what the operator manual allows. Riders must go straight up and down slopes, never across, and only within the manual limit on dry grass. Many hilly half-acre lots have short, steep banks where a rider is the wrong tool. A rear-wheel-drive walk-behind mowed across the slope is usually the safer and simpler choice.
How long does it take to mow a hilly half acre?
About 1 hr 25 min with a 21 inch self-propelled mower, 1 hr 12 min with a 25 inch deck and about 60 minutes with a 30 inch walk-behind. These assume a 3 mph pace and 65 percent efficiency for hills. The same half acre on flat ground takes about 1 hr 9 min with a 21 inch mower, so hills add roughly 23 percent.
Front-wheel drive or rear-wheel drive for a sloped yard?
Rear-wheel drive. When you mow uphill, weight transfers onto the back wheels, so rear drive keeps traction while front drive tends to spin. Front-wheel drive is easier to pivot on flat lawns by pressing down on the handle, but that advantage disappears on slopes. Every walk-behind recommended for this page uses rear-wheel drive.
What slope is too steep to mow with a push mower?
The operator manual sets the limit, so check yours first. As a practical rule, if you cannot stand and walk across a slope with secure footing, do not mow it. A 20 percent slope, which rises 24 inches over 10 feet, is already steep to walk across. Past that, switch to a string trimmer, groundcover or a robot mower rated for the grade.
Researched, not professional advice. This page is compiled from published specifications, manuals, labels and owner-review consensus, not hands-on testing. Follow the manufacturer's instructions and product label, and consult a qualified professional where safety, chemicals, fuel or structures are involved. As an Amazon Associate we earn from qualifying purchases.