How an estimate is built

An estimate is not a lookup. It is a sequence of judgements about your specific ground, and understanding the sequence tells you which parts of it you can change.

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

Who this is for

Anyone wondering why quotes vary so widely on the same parcel
Landowners who want to reduce the price without reducing the scope
People preparing to brief contractors properly

The short answer

The contractor is estimating machine hours, then adding everything that is not machine hours: mobilisation, material handling, disposal, and risk.

Machine hours come from fibre volume — density multiplied by stem size — adjusted for terrain, access, obstacles, and how selective the work has to be. Area only matters as an input to volume.

Everything else is largely fixed or driven by decisions you make: where material goes, how deep removal reaches, how much certainty you want in the price.

The parts you can influence are the material decision, the below-grade decision, the area actually cleared, and how much uncertainty you remove before they quote.

What changes the answer

Density and largest stem diameter
What happens to the cut material
Whether below-grade removal is included
Access and terrain
How assessable the site is
How much certainty you want in the number

The estimating sequence

Roughly in this order, and each step depends on the one before.

How an estimate is assembled, and whether you can influence each step
Step	What the contractor judges	Can you influence it?
Scope	What is actually being asked for	Yes — the largest lever you have
Fibre volume	Density multiplied by stem size	Only by reducing the area
Machine and attachment	What fits the site and the growth	Indirectly, via access
Production rate	Volume per hour in these conditions	Slightly, via preparation and marking
Machine hours	Volume divided by rate	Follows from the above
Material handling	Gathering, processing, or hauling	Yes — this is a decision, not a fact
Disposal	Destination and tipping	Yes
Below-grade work	Whether roots come out	Yes
Mobilisation	Getting equipment there and back	Only by combining phases
Risk and contingency	What might not be visible	Yes — by making the site assessable

Where the biggest lever is

It is not negotiation. It is the material decision, and it is yours to make.

On a full-removal job, gathering, loading, hauling, and tipping the cut material is frequently the largest single component — often larger than the cutting. Leaving the material on site removes that component entirely.

The second largest lever is below-grade work. Removing root plates converts a surface job into an earthworks job with holes to backfill and settlement time attached. Where your end use does not require it, not buying it is a substantial saving that costs you nothing.

The third is area. Clearing what you have a use for rather than the whole parcel scales the cost down and avoids taking on maintenance across ground you were not going to use.

Notice that none of these three is a discount. They are decisions about what you are buying.

Why contingency is in the number

The risk component is real and it is worth understanding rather than resenting.

A contractor pricing a site they cannot fully see is carrying the possibility of buried fencing, rock, unexpectedly large stems, softer ground than it looks, and old dumped material. Any of those can stop work or damage equipment.

Rationally, they include an allowance sized by how uncertain they are. On a clean, visible, uniform site that allowance is small. On a heavily overgrown parcel it is large, and you pay it whether or not the risk materialises.

The way to reduce it is not to argue about it but to reduce the uncertainty: open a small area first, tell them what the property was used for, point out the old fence lines, and be honest about what you do not know. Information is cheaper than contingency.

What you can do before they quote

Each of these reduces either the hours or the risk allowance, and none of them costs money.

Measure the largest trunk diameter and the access width, and provide both.
Decide what the ground has to do afterwards, and say it in one sentence.
Decide whether a residue layer is acceptable where it would sit.
Flag the trees you are keeping and mark the services you know about.
Tell them the property’s history — what it was used for, what was on it, where fences ran.
Reduce the area to what you actually need cleared.

Reading the estimate you receive

Once you understand how the number was built, the document in front of you becomes readable.

Look for the components. A quote that separates cutting, material handling, disposal, and below-grade work lets you see where the money is and which parts you could change. A single total tells you nothing and cannot be compared with anything.

Look for the assumptions. Stem size, density, ground conditions, and access should appear somewhere, because those are what the hours were derived from. A quote with no stated assumptions cannot be held to anything if the site turns out differently.

Look for what happens if the assumptions fail. A stated mechanism — a reassessment point, a rate for additional time, a threshold at which you both talk — is the mark of somebody who has been wrong before and handled it well.

What drives the cost

Cost drivers on this kind of project
Driver	Effect
Material destination	Frequently the largest single component on a removal job, and it is your decision.
Below-grade extent	Converts a surface job into earthworks, with backfill and settlement attached.
Area cleared	Scales fibre volume, and scales the maintenance you take on afterwards.
Risk allowance	Sized by how unassessable the site is. Reduced by information, not negotiation.
Mobilisation	Charged per arrival, which is what makes phasing more expensive per acre.
Access constraint	Caps machine class, and a smaller machine needs more hours for the same work.

Common mistakes

Negotiating the number before checking the scope is right
Buying below-grade removal for ground that will only be grazed
Clearing the whole parcel out of tidiness
Withholding what you know about the site history
Requesting a fixed price on a site nobody could see into

Questions to ask a contractor

Which component of this price is the largest, and why?
What would change if the material stayed on site?
How much of this is contingency for what you cannot see?
What could I tell you that would reduce that contingency?

What to do next

Write one sentence describing what the ground must do afterwards
Decide the material and below-grade questions before requesting quotes
Provide the largest stem diameter and access measurements
Reduce the area to what you have a genuine use for

Questions people actually ask

Why will nobody give me a price per acre?

Because area is only an input to fibre volume, and two adjacent acres can differ by a large multiple in how much woody material they hold. A per-acre figure quoted without seeing the growth is an average of that contractor’s past jobs.

Can I get the price down by negotiating?

A little, sometimes. You can usually get it down much further by changing the scope — leaving the material, skipping below-grade work your end use does not need, or clearing less area. Those are the levers with real movement in them.

Is a higher quote a better contractor?

Not necessarily, and it frequently reflects a broader scope. Most large gaps come from one of four things: what happens to the standing growth, where the material goes, whether roots come out, and what the surface is like. Find the difference before concluding anything about quality.

Should I tell contractors what other quotes said?

Sharing the scope descriptions is genuinely useful — it lets each of them explain their difference. Sharing only the numbers invites matching a price without matching the work, which is the opposite of what you want.