A typical backyard pool void takes roughly 50-120 cubic metres of fill, depending on the pool’s length, width and depth and whether it’s a full removal or a partial fill-in over a retained lower shell. The simplest way to estimate your own number is length × width × average depth, in metres, which gives you cubic metres of void, then adjust for how much of the old shell (if any) is staying in the ground. Getting this number right before fill is ordered avoids the two most common budget surprises on a pool removal: paying for fill you didn’t need, or running short mid-job and paying a rushed second delivery fee.
This guide walks through the calculation step by step. It’s a planning tool, not a substitute for the site inspection and formal quote that sets your actual volume; real pool shapes are rarely a clean rectangle, and only a contractor standing at the hole can confirm the true figure. Our excavation, backfilling and compaction service covers how that fill is placed and compacted once it’s on site.
The Basic Calculation: Length × Width × Average Depth
Start with the pool’s internal dimensions, then apply this rough formula:
Volume (cubic metres) = Length (m) × Width (m) × Average Depth (m)
For a full removal, average depth is the depth of the entire excavated void, since the whole shell is coming out and the hole goes right down to the base of the old pool floor. For a pool that steps from 1.1 m in the shallow end to 2.0 m in the deep end, the average depth is roughly (1.1 + 2.0) ÷ 2 = 1.55 m, though a contractor will usually take a few measurements along the pool’s length rather than relying on just the two extremes, since most pools have a sloped floor rather than a single even step.
Worked example, full removal: A pool 8 m long, 4 m wide, averaging 1.5 m deep: 8 × 4 × 1.5 = 48 cubic metres of void to fill. Add a margin for the walls and coping zone excavated around the shell’s edges (typically another 10-20%, since the hole is usually a bit wider than the pool itself once the shell and its surrounding backfill zone are accounted for), and you land close to the 50-60 cubic metre range for a mid-sized family pool, consistent with the lower end of the typical 50-120 m³ range seen across the region.
Full Removal vs Partial Fill-In: Why the Volume Differs
This is where the calculation genuinely diverges, not just in price but in the physical amount of fill needed.
Full removal takes the entire shell out, so the fill volume is close to the full calculation above, the complete void down to the base of the excavation.
Partial fill-in leaves the lower section of the shell in the ground, cut down and holed for drainage, with fill placed only in the upper portion. Because part of the void is still occupied by the retained shell (or by suitable broken shell material seated in the base, on a concrete pool), the volume of new fill required is meaningfully less than a full removal of the same pool, often somewhere between a third and two-thirds of the full-removal figure, depending on how much of the shell is retained and how it’s holed and prepared.
This is one of the reasons a partial fill-in costs less than full removal: less material has to be sourced, delivered and compacted, on top of the reduced demolition and cartage work. It’s also why the two methods aren’t simply “cheap version, expensive version” of the same job; they use genuinely different volumes of fill.
From Cubic Metres to Truckloads
Fill is usually delivered by tipper truck, and truck capacities vary, but a standard tipper commonly carries somewhere in the order of 6-10 cubic metres per load, depending on the truck and the fill material’s density. Using the 48 cubic metre worked example above:
- At 6 m³ per load: roughly 8 truckloads
- At 10 m³ per load: roughly 5 truckloads
A larger family pool toward the top of the typical 50-120 m³ range could need anywhere from 8 to 20 truckloads depending on truck size, which is worth knowing when a contractor talks through access and street truck movements at inspection; it’s not an abstract logistics detail, it directly affects how many days of deliveries your street will see.
Why the Fill Volume Isn’t Just “Dirt In, Job Done”
Fill isn’t tipped in as one mass; it’s placed in layers, typically 200-300 mm at a time, with each layer compacted before the next goes on. This changes how much fill you actually need compared with a naive volume calculation, because compacted fill is denser than loose fill: a cubic metre of loose material doesn’t become a cubic metre of finished, compacted ground. Contractors account for this compaction factor when ordering fill, which is one reason the volume calculation above is a useful planning estimate rather than an exact order quantity, and one more reason a formal quote (rather than a DIY number) is what actually gets fill ordered correctly the first time.
Fill material also matters for how reliably it compacts. Clean, compactable material, virgin excavated natural material (VENM) or equivalent approved clean fill, behaves predictably in layers. Uncontrolled fill (green waste, mixed demolition rubbish, unknown “free fill”) doesn’t compact reliably regardless of how carefully it’s placed, and can leave voids that show up as settlement later. See our guide on soil testing and compaction certification after pool fill-in for how that compaction is actually verified once the fill is in.
When the Volume Matters Beyond Just Ordering Fill
If you’re planning to ever build over the filled area, a shed, garage, granny flat or extension, the volume and quality of fill matters for more than just budgeting. A structural engineer will want to know how deep the fill is, what it’s made of, and how it was compacted before signing off on footings, which is exactly what a geotechnical report after pool fill-in documents. Getting the volume calculation right at the planning stage, and confirming fill type and compaction standard with your contractor before work starts, is far cheaper than discovering the wrong fill was used after a slab has already gone down.
How Much Fill Does a Pool Need: FAQs
Is the length × width × average depth formula accurate enough to budget with? It’s a reasonable planning estimate for a rectangular or near-rectangular pool, but most real pools have a sloped floor, rounded corners or a freeform shape, and the excavated void is usually somewhat wider than the pool itself once the shell and surrounding backfill zone are included. Treat it as a ballpark figure to sanity-check quotes against, not a number to order fill from directly.
Does a kidney-shaped or freeform pool need a different calculation? The same basic principle applies, but the width varies along the pool’s length rather than staying constant, so an accurate volume needs the pool measured at several points rather than a single length-by-width figure. This is one of several reasons a site inspection, rather than a DIY spreadsheet, sets the final ordered quantity.
Why did my neighbour’s similar-sized pool need noticeably less fill than mine? The most likely explanation is method: a partial fill-in over a retained shell needs meaningfully less fill than a full removal of a similarly sized pool, since part of the old void is still occupied by the retained lower structure. Pool depth and shape differences can also account for a real gap between two pools that look similar from the street.
Do I pay for fill separately from the removal quote? Usually no, fill supply and placement is typically included in a bundled removal or fill-in quote, priced against the calculated volume for your specific pool. It can be priced as a standalone item too, covered on our excavation and backfill page, if you’re getting a partial project quoted separately.
Want an accurate fill volume for your actual pool, not just an estimate? Get a free quote and a independent local contractor will measure your pool and confirm the real number on site.