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Mower Deck Size Calculator: What Size Mower for Your Acreage

Last updated Researched from specs, manuals and owner reviews, not tested in person

Quick answer

For open, flat lawns: under a quarter acre needs a 20 to 22 inch walk-behind, half an acre to 1 acre a 30 to 42 inch rider, 1 to 2 acres a 42 to 48 inch deck, 2 to 3 acres 48 to 54 inches, and 3 to 5 acres a 54 to 60 inch zero-turn. Go one size smaller when trees and beds crowd the lawn.

Deck width decides how many passes your lawn takes, and passes decide your Saturday. This calculator takes the mowable area (not the lot size), your terrain and an optional time budget, then recommends a deck range and mower type and estimates how long each common deck size takes. The matching mowers below update to your result. Not sure of your area? Measure it first with the lawn size calculator.

Mower deck size calculator

Grass only, not the whole lot.

Recommended deck

42 to 48 in

Mowers that match your deck size

Top matches update when you calculate.

On this page
  1. What size mower deck do I need for my acreage?
  2. How long does it take to mow 1 acre and 2 acres by deck size?
  3. How is the mower deck size calculated?
  4. Should I get a bigger deck than I need?
  5. What size mower do I need for hills?
  6. Which mowers match my deck size?

What size mower deck do I need for my acreage?

The table below uses open, fairly flat lawn, a 15 percent overlap between passes, and 80 percent efficiency for turns and trimming. Times assume the largest deck in each range at a typical cutting speed for that mower type.

Recommended deck size by lawn area (open, flat lawn)
Mowable areaDeck widthMower typeTime with largest deck
0.25 acres20 to 22 inwalk-behind (push or self-propelled)33 min
0.5 acres21 to 30 inself-propelled walk-behind or a 30 in. rider32 min
0.75 acres30 to 42 inriding mower (lawn tractor or compact zero-turn)35 min
1 acre30 to 42 inriding mower (lawn tractor or compact zero-turn)46 min
1.5 acres42 to 48 inlawn tractor or zero-turn42 min
2 acres42 to 48 inlawn tractor or zero-turn56 min
3 acres48 to 54 inzero-turn or large lawn tractor1 hr 15 min
4 acres54 to 60 inzero-turn1 hr 30 min
5 acres54 to 60 inzero-turn1 hr 52 min

How long does it take to mow 1 acre and 2 acres by deck size?

Mowing time by deck width
DeckCutting speedAcres per hour1 acre2 acres
21 in3 mph0.432 hr 19 min4 hr 37 min
30 in4.5 mph0.931 hr 5 min2 hr 9 min
42 in4.5 mph1.346 min1 hr 32 min
46 in4.5 mph1.4242 min1 hr 24 min
48 in6.5 mph2.1428 min56 min
54 in6.5 mph2.4125 min50 min
60 in6.5 mph2.6822 min45 min

How is the mower deck size calculated?

Deck width is the cutting width of the blades, measured in inches across the deck. Each pass really covers about 85 percent of that width, because you overlap the previous stripe to avoid leaving uncut ridges. The formula is:

  • Effective width (ft) = deck inches x 0.85 / 12
  • Acres per hour = speed in mph x 5,280 x effective width x efficiency / 43,560
  • Minutes = acres / acres per hour x 60

Efficiency is 0.80 for open lawn, 0.65 for hills where you slow down and cut across the slope, and 0.60 for yards full of trees and beds where you spend time turning and trimming. A 54 inch zero-turn at 6.5 mph mows about 2.4 acres an hour on open ground, while a 21 inch self-propelled at 3 mph covers about 0.43 acres an hour, which is why one acre is well over two hours of walking but about a 25 minute ride.

Should I get a bigger deck than I need?

Not always. A wider deck saves time on open lawn, but it has three costs people forget. It needs a wider gate: a 54 inch deck with its discharge chute is about 60 to 66 inches wide, and many backyard gates are 48. It needs more storage room: check the shed size for a zero-turn before you buy. And it scalps more on uneven ground, because a long deck bridges dips and catches crowns. If your lawn has lots of trees, beds and tight corners, the time you save on straightaways is lost trimming, so one size smaller is usually the better buy.

The honest middle ground for most 1 to 2 acre suburban lots is a 42 to 48 inch deck. For a comparison of the two most common big-lawn choices, see zero-turn vs lawn tractor.

What size mower do I need for hills?

Slope changes the mower type more than the deck size. Zero-turn mowers steer with their rear drive wheels, so on wet or steep ground they can lose traction and steering together. Most zero-turn operator manuals set a low maximum slope, and you must follow the limit in your own manual. A lawn tractor steers with its front wheels and holds a line across a grade better, and a rear-wheel-drive self-propelled walk-behind is the safest choice for short steep banks. Robot mowers with all-wheel drive are rated for much steeper grades than riders; see robot mowers for hills. Our full guide to mowing on slopes safely covers how to measure your grade.

Which mowers match my deck size?

The grid under the calculator filters to the result, but the short version: the Husqvarna Z254F 54 in. Zero Turn Mower (54 inch, $3,985.00) is the value zero-turn for 2 to 4 open acres, the Husqvarna TS 120 46 in. Lawn Tractor is a 46 inch lawn tractor for 1 to 2 acres with some slope, the EGO POWER+ Z6 ZT4204L 42 in. Electric Zero Turn Mower is the quiet 42 inch battery zero-turn for up to about 2 acres, and the EGO POWER+ LM2135SP 21 in. Select Cut Self-Propelled Mower Kit is the battery walk-behind for small lots. For every option ranked by tier, see the best zero-turn mowers, the best riding mowers and mowers for 1 acre.

Frequently asked questions

What size mower deck do I need for 1 acre?

A 42 inch deck is the usual pick for one open acre. On a lawn tractor at about 4.5 mph it takes roughly 45 minutes including turns, or about 32 minutes on a 42 inch zero-turn. If the acre has many trees and beds, a 42 inch zero-turn saves time turning; if it has slopes, a 42 or 46 inch lawn tractor is safer. A walk-behind will do it, but plan on well over two hours.

What size zero turn mower do I need for 2 acres?

For 2 open acres, a 48 to 54 inch zero-turn is the sweet spot. A 54 inch deck at 6.5 mph mows 2 acres in about 50 minutes, while a 42 inch zero-turn takes about 64 minutes. Check gate width and storage first, since a 54 inch deck with its chute can run 60 inches or wider.

How do I measure my mower deck size?

Deck size is the cutting width, which is the blade tip to blade tip span, not the outside width of the deck housing. It is almost always printed in the model name or on a decal, such as Z254F for a 54 inch deck. To measure, lift the deck safely with the engine off and key removed, and measure across the path the blades sweep.

Is a 42 or 46 inch deck better for 1.5 acres?

A 46 inch deck saves about 10 percent of your mowing time on open ground, roughly five minutes per mow on 1.5 acres. That matters less than fit: if your gates, shed door or trailer are tight, the 42 inch deck is the better buy. On hilly or tree-filled lots the difference in time mostly disappears.

Does a bigger mower deck cut worse?

A larger deck can scalp more on bumpy lawns because the long housing bridges dips and rides over crowns, and fabricated decks on higher-end mowers resist this better than stamped ones. On smooth lawns cut quality depends more on sharp blades, deck height and ground speed than on width. Slowing down in thick grass improves the finish on any deck size.

How long should it take to mow a lawn?

A quarter acre takes about 35 to 50 minutes with a 21 inch walk-behind. Half an acre takes about 25 to 35 minutes on a 30 to 42 inch rider. One acre takes about 25 to 45 minutes on a rider depending on deck width and mower type, and 2 acres about 50 to 90 minutes. Hills, trees and bagging can add 25 to 50 percent to any of these.

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.