You're standing in a backyard mid-afternoon, tape in one hand, notebook in the other, back aching from a day on the tools. The client wants paving out the back and a retaining wall down the side fence. You measure it, work out your dig depth, jot down the cubic metres, and that night you price the soil removal off that number. I reckon that's where heaps of us quietly lose money.
If you've ever searched soil bulking factor landscaping, the calculators and reference tables you come across are useful, but I want to follow it through to the thing we actually need, which is the line item on a landscape quote. So that's what I want to do here: dig, loose volume, truck loads, tonnes, tip, line item.
Soil bulking factor: landscaping's forgotten line item
Once soil comes out of the ground, it doesn't stay the same size. It loosens up and takes more room. Booms Up Civil, an earthworks outfit in NSW, says this bulking or swell can add anywhere from 15% to 40% to the material you have to deal with. Their own example is 50 m³ of clay in the ground easily becoming about 65 m³ once it's sitting loose in the back of a truck.
Engineering ToolBox has a reference table that puts clay at 20–40% swell, loam at 15–25% and general soil at 20–30%.
ConstructCalculators explains it as three states: bank (in the ground), loose (after you've dug it) and compacted. Loose is the one you haul.
That's the key bit. The number in your notebook is bank volume. But trucks, skips and barrows don't carry bank volume. They carry loose.
Walking through a job
Let's make one up so the maths is easy. This is an example, not a market rate.
Say it's 25 square metres of paving, and you need to dig out 200 mm for base and pavers. That's 5 m³. Then there's a block retaining wall down the side, and between the footing and cutting back the bank, say that's another 5 m³. So you've got 10 m³ in the ground.
Say you're digging clay. I'll use 30%, which sits in the middle of the Engineering ToolBox range for clay.
The formula is simple: loose volume = bank volume × (1 + swell). So 10 × 1.3 = 13 m³ loose.
One trap. ConstructCalculators points out you always apply swell to the bank volume. If you apply it to a number that's already loose, you've counted it twice and you'll overquote the removal. Measure the hole, then add the swell once.
From cubic metres to truck loads
Booms Up Civil's calculator works on a standard 12 m³ tandem tipper. So on volume alone:
- Priced off bank volume, 10 m³ is one load.
- Priced off loose volume, 13 m³ is two loads.
ConstructCalculators makes the same point with their own example: work out truck trips on loose volume, not bank volume, or you'll come up short. That's before you've even checked weight limits with whoever's carting it.
Skips work the same way. Count the bins off the loose number. And if access is tight and it's hand dug and barrowed out, more loose volume means more barrow trips, which means more hours for the guys. Every one of those is a line you've priced. Get the volume wrong and the difference comes straight out of your margin, not the client's pocket.
Then the tonnes, and the tip
Here's the bit people miss even when they've remembered bulking. Booms Up Civil notes that most tips and haulage operators charge by the tonne, so you need the weight as well as the cubic metres. They give rough densities of about 1.1–1.4 t/m³ for topsoil, 1.5–1.7 for sand and 1.6–2.0 for clay.
The dirt doesn't get heavier when you dig it. It just takes up more room. So I work the tonnes off the in-ground volume. Our 10 m³ of clay at 1.6–2.0 t/m³ is roughly 16 to 20 tonnes.
In Victoria, EPA Victoria says a waste levy must be paid on all waste received at a landfill. For industrial waste that is soil (Category D), the metro levy is $169.79 a tonne from 1 July 2025 to 30 June 2026, rising to $177.19 a tonne from 1 July 2026. Call our example 18 tonnes and the levy alone is about $3,056 at the current rate, or about $3,189 after 1 July 2026. That's the levy, not a tip's price list, so ring your tip and get their actual rate per tonne before you lock the quote in. If you're outside Victoria, check how your own state handles it.
And watch the site history. Booms Up Civil says clean fill is cheaper to get rid of than contaminated soil, which has to go to a licensed facility, and the history of a site can mean a contamination assessment first. EPA Victoria lists contaminated soils under Category B at $296.18 a tonne from 1 July 2026. If you're digging somewhere that's had a past life, ask the question before you price it.
Where the margin actually leaks
So there are two separate misses. Forget bulking and you short yourself on trucks, bins, barrow trips and labour. Forget tonnes and you short yourself at the tip. Do both and the job can go backwards on dirt alone.
On a quote, put the dig on three lines, not one:
- Excavation: 10 m³ in ground (labour and machine)
- Soil removal: 13 m³ loose, 2 tipper loads
- Disposal: approx. 16–20 tonnes at the tip's rate
The 30% is a planning number, not gospel. ConstructCalculators says swell depends on moisture, compaction and how the soil's dug, and if you've got a geotech report or supplier data, use that instead. If your carrier knows the local dirt, ask them.
Soil is not hard, just easy to forget at 9pm when you're building quotes on the laptop. That's partly why, when we built Ask Willow, our AI-powered quote platform for landscapers, we made it prompt for the hidden costs from the site walk, including soil expansion, skip bins, and access and slope. It's not perfect, and you still check the numbers, but it's a lot harder to forget the second truck when you are being asked if you want to include it.
The takeaway
On your next quote, write down two numbers for every dig, not one: the in-ground cubic metres and the loose cubic metres. Price your trucks, skips and barrow time off the loose number. Price the tip off tonnes, worked from the in-ground volume, at a rate you've actually confirmed. It takes five minutes, and it's money you've already earned staying in your pocket.
Sources
- [[FREE] Soil Excavation Volume Calculator | Estimate Spoil in m³ & Tonnes](https://boomsupcivil.com.au/blog/soil-excavation-volume-calculator/)
- Soil and Rock - Bulk Factors
- ConstructCalculators - Free Construction Calculators
- Waste levy