TryBuildCalcGarden Bed Topsoil Fill Calculator (Planting Bed Fill Volume)
Size topsoil for your garden bed instantly.
🕒 Last updated: September 19, 2026
Inputs
ℹ️For an irregular area, measure its overall rectangular footprint, or switch to By Total Area above.
ℹ️Typical for Premium Garden Soil Blend: 6-12 in.
ℹ️A richer topsoil blend formulated for planting, typically with added organic matter for structure and nutrients. Suited to filling raised garden beds and new planting areas to a workable rooting depth.
Delivery
ℹ️0.75 cu ft is a common standard US retail bag; 25-50 L covers common UK/AU bag sizes. Topsoil bags run smaller than mulch bags since topsoil is much denser.
Cost
Topsoil Needed
17 bags
24.53 cu ft total (0.695 m³)
Fill Area
32 sq ft
2.97 m² at 8" (20.3 cm) deep
Volume
Bare volume: 21.33 cu ft (0.79 cu yd / 0.604 m³)
Order volume (+15% settling/waste): 24.53 cu ft
0.909 cu yd / 0.695 m³ / 694.7 L
Bags
Bag size: 1.5 cu ft (42.5 L)
Bags needed: 17
Each bag covers ≈2.3 sq ft at 8" deep.
Premium Garden Soil Blend
A richer topsoil blend formulated for planting, typically with added organic matter for structure and nutrients. Suited to filling raised garden beds and new planting areas to a workable rooting depth.
Typical depth range: 6-12 in (general practice guidance, not a fixed standard)
Assumptions Used
Order volume adds a 15% settling/waste allowance on top of the bare fill volume (area × depth), covering typical settling and compaction once topsoil is watered in and worked. Bag sizes are stored as a canonical liter volume so both common US cu-ft retail bags and common UK/AU litre bags can be selected from the same list; results are always shown in cu ft, cu yd, m³, and litres together. Bulk/loose figures assume a ≈1 m³ (≈35 cu ft) bulk/FIBC bag as an additional reference figure — many US suppliers instead sell bulk topsoil loose by the cubic yard, which is shown directly. This calculator estimates material quantity only — it does not verify existing grade, drainage, or soil testing/amendment needs.
Diagram simplified for clarity (not to scale) — fill area shown schematically, topsoil depth shown proportionally.
Looking for the verification checklist, reference tables, tips, or common mistakes?See the complete Topsoil Calculator.
Garden bed topsoil fill volume
A planting bed generally needs a deeper topsoil fill than a lawn topdressing to give plant roots a real workable depth — commonly in the range of 6-12 inches for a garden or raised bed, depending on what's being planted.
This page defaults to an 8 ft × 4 ft bed at 8 in deep with a premium garden soil blend — edit the inputs above to match your actual bed size and preferred fill depth. For a layered soil-mix recipe (rather than a simple volume fill), a dedicated raised bed soil-mix calculator is a better fit.
Topsoil Calculator Formula: How Is It Determined?
Fill area and depth combine into a bare volume, a settling/waste allowance is added, then the order volume converts to either a bag count or a bulk quantity.
Step 1 — Fill Area
By Dimensions: Area = Length x Width
By Total Area: Area = entered value (converted to sq ft if entered in m²)
Either enter a rectangular area's length and width, or enter its total area directly — useful for an irregular lawn, bed, or plot where length x width doesn't apply.
Step 2 — Bare & Order Volume
Bare Volume = Area x Depth
Order Volume = Bare Volume x (1 + 15% settling/waste)
The 15% allowance covers typical settling and compaction once topsoil is watered in and worked — a bit higher than a loose organic mulch's allowance, since topsoil compacts more.
Step 3a — Bagged
Bags = ceil(Order Volume / Bag Volume)
Bag volume is stored as a canonical liter figure internally, so both cu-ft-sized (US) and litre-sized (UK/AU) bags come from the same preset list, or enter a custom bag size in either unit.
Step 3b — Bulk / Loose
Order Volume shown directly in cu yd and m³
Bulk Bags (≈1 m³ each) = ceil(Order Volume in m³)
Bulk topsoil is most often bought loose by the cubic yard (common in the US) — the bulk/FIBC (~1 m³) bag count is shown as an additional reference figure, since that's a common bulk-bag size in the UK and Australia.
Worked Example
This example walks through your current inputs above, using the same steps as the Formula section.
Input Values Used
| Input | Value | Why it is used |
|---|---|---|
| Fill Area | 32 sq ft (2.97 m²) | Sets bare volume |
| Depth | 8 in (20.3 cm) — Premium Garden Soil Blend | Sets bare volume and depth-advisory check |
| Delivery Method | Bagged | Sets bag count or bulk quantity |
| Bag Size | 1.5 cu ft (≈42 L) — jumbo US bag — 1.5 cu ft (42.5 L) | Sets the bag-count divisor |
Step 1 & 2 — Volume
| Calculation | Result |
|---|---|
| Bare Volume = 32 sq ft x (8/12) ft | 21.33 cu ft (0.79 cu yd / 0.604 m³) |
| Order Volume = Bare Volume x (1 + 15%) | 24.53 cu ft (0.909 cu yd / 0.695 m³) |
Step 3 — Bags
| Calculation | Result |
|---|---|
| Bags = ceil(24.5 / 1.5 cu ft per bag) | 17 bags |
Figures above are rounded for display; the bag/bulk count is always calculated from full, unrounded values, so it can occasionally look off by one bag if you redo the division yourself using the rounded figures shown.
Therefore, a 32 sq ft area at 8" deep needs approximately 17 bags of premium garden soil blend.
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Disclaimer: This calculator provides approximate results for planning and estimation purposes only. Actual requirements may vary based on site conditions, materials, workmanship, and local building regulations. Always consult a qualified engineer, architect, or construction professional before making final decisions.