What size machine does the job need?

Bigger is not better and smaller is not gentler. The right machine is the largest one that fits your access and that your soil will tolerate — in that order, because access is a hard limit and capability is a preference.

Published by the Land Clearing Authority editorial team · Last revised 2026-07-29 · Editorial policy · Corrections

Who this is for

Landowners told a machine will not fit, or that a bigger one is needed
Anyone whose site has a gate, a bridge, or soft ground
People comparing contractors who own different equipment

The short answer

Access is checked first because it is absolute. A machine that will not pass the narrowest point cannot work your site at any price, regardless of how suitable it would otherwise be.

Ground conditions are checked second. A machine your soil will not carry either sinks, ruts, or compacts ground you needed afterwards — so ground pressure constrains the choice independently of size.

Capability is checked last. Within what fits and what the ground carries, the largest stems and the density determine whether the machine can do the work economically.

When those three conflict, the site wins. An oversized machine on a constrained site spends its day repositioning; the answer is a smaller machine and more hours, not a bigger machine and a damaged property.

What changes the answer

Narrowest and lowest point on the route in
Soil type and moisture at the time of work
Largest stem diameter on the property
Slope and how much of it there is
Whether material has to be moved as well as cut
What the ground has to do afterwards

The three constraints, in checking order

Work down the table. The first row that fails eliminates a machine regardless of the rows below it.

What each constraint decides, and what it rules out
Constraint	Measured by	What it rules out
Access width	Narrowest point including posts	Any machine wider, absolutely
Overhead clearance	Lowest wire or branch	Any machine taller with attachment raised
Crossing capacity	Load limit of any bridge or culvert	Anything the route cannot carry
Ground pressure	Weight over contact area	Machines too heavy for wet or soft soil
Slope stability	Steepest working section	Machines with an unsuitable centre of gravity
Diameter capability	Largest stem on the property	Machines that cannot cut it economically
Turning space	At the work area and bends	Machines that cannot manoeuvre there

Why an oversized machine is a bad outcome, not a bonus

Owners often assume the biggest available machine is the best value. On a constrained site the opposite is true.

A machine too large for the working area spends its time positioning rather than cutting. It cannot get close to boundaries or between retained trees, so the work it can actually do is a subset of the work you wanted.

It also does more damage. Greater weight over the same contact area means more compaction and deeper rutting, and on ground that has a productive use afterwards that is a real cost you pay later.

The genuine advantage of a larger machine is on open, dry, uniform ground with large stems, where it converts power into production. Outside those conditions it is the wrong tool.

When two machines beat one

Mixed sites frequently do not have a single right answer, and the honest scope reflects that.

A parcel that is mostly light growth with a scattering of large stems is a poor fit for any single machine: sized for the large stems it is too big for efficient work on the light growth, and sized for the light growth it stalls on the large ones.

The usual answer is sequencing — the large stems handled individually, then the area processed with a machine matched to the bulk of the growth. That is two operations and it is frequently cheaper than forcing one machine through both.

The same applies to access. Where the outer part of a parcel is open and the back is reachable only through a gate, two machine sizes may be the efficient answer.

What to ask, in your own terms

You do not need to know machine model names. These four questions translate the specification into your site.

How wide is the machine, and how tall with the attachment raised?
What is its ground pressure, and what does that mean for my soil in the month you would work?
What is the largest stem it will take economically, and what happens above that?
Given my access, is this the machine you would choose, or the one you have available?

What to do when the answers conflict

On many properties the three constraints do not agree, and knowing the priority order prevents an expensive compromise.

Access beats everything, because it is absolute. A machine that cannot reach the work is not a candidate at any price and no amount of capability compensates.

Soil comes second, and it beats capability wherever the ground has a productive use afterwards. A machine that can cut your largest stems but will rut a field you intend to graze has solved the wrong problem.

Capability comes last, and where it cannot be satisfied within the first two constraints the answer is usually sequencing rather than a bigger machine: handle the few oversized stems separately, then process the bulk with equipment matched to the site.

What drives the cost

Cost drivers on this kind of project
Driver	Effect
Access limit	Caps machine class. A smaller machine on the same growth means more hours.
Ground pressure requirement	Low-ground-pressure equipment may cost more per hour and far less in damage.
Diameter capability	Stems above the economical ceiling need a second approach and a second cost.
Number of machines	Mixed sites may need two, which is two mobilisations and often still cheaper.
Transport	Larger equipment costs more to move to and from the site.

Common mistakes

Choosing on horsepower without checking width or ground pressure
Assuming a bigger machine finishes faster on a constrained site
Measuring a gate opening rather than the width including posts
Forgetting overhead clearance, which strands machines more often than width does
Accepting one machine for a site with a wide spread of stem sizes

Questions to ask a contractor

How wide and how tall is the machine you would bring?
What is its ground pressure, and is my soil suitable in that season?
What is the largest stem it takes economically?
Would this site be better served by two machine sizes?

What to do next

Measure the narrowest and lowest points on the route, with a tape
Measure the largest trunk diameter on the property
Give both figures to every bidder before they quote
Run the site access checker to see which constraints apply

Questions people actually ask

Can compact machines do real clearing work?

Yes, within their diameter range, and on constrained sites they are frequently the only option that can reach the work at all. The trade-off is hours: a smaller machine on the same growth takes longer, which is a cost rather than a failure.

Are tracks always better than wheels?

Usually for ground pressure, because tracks spread weight over a much larger contact area. Tracks can still damage a surface when turning, and a well-chosen wheeled machine on dry firm ground may be entirely appropriate.

What if nothing fits my access?

Then the options are widening the access temporarily, working from a different approach, or hand and small-equipment work at a different cost structure. It is worth establishing early, because it changes the whole shape of the project.

Should I ask for a specific machine?

Better to state the constraints and let the contractor match to them. Specifying a machine you have read about risks ruling out a better-suited one they own, and it moves responsibility for the choice from them to you.