Soil Volume Calculator

Bed footprint:

Inside dimensions:

Length × width × unit

Inside diameter:

Value and unit

Measured area:

Value and unit

Matching beds:

beds

Target soil depth:

Value and unit

Soil profile:

Top-up credit and allowance default to zero. Supplier logistics stay off until enabled, so opening Advanced does not change the geometric result.

Existing soil depth:

Value and unit

Settlement:

Exact%

Include supplier and handling plan:

Enable bag count, bulk-ticket rounding, wheelbarrow loads, prices, and vehicle trips.

Soil order worksheet with quantity and calculation basis.
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Soil delivery plan with supplier and handling quantities.
Plan item	Quantity	Decision note	Copy
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Filling a raised bed or topping up an existing one is a volume problem, not just an area measurement. The footprint tells how much ground the bed covers; the missing depth determines how much soil must be added. A shallow error repeated across a wide bed can change the order by several bags or a noticeable fraction of a bulk delivery.

Measure inside the bed walls. For a new empty bed, the fill depth normally matches the target soil depth. For a top-up, measure the current soil level and credit only the depth already present. Soil above the target does not create a negative order, and different existing depths across one bed are better handled as separate sections or by using a representative average.

Net fill: The empty volume between the existing level and the target level.
Settlement allowance: An explicit percentage added after net fill for settling, grading, and small measurement variation.
Bulk ticket: The supplier quantity after a minimum order and delivery increment are applied.

Volume and weight answer different planning questions. Cubic metres, cubic yards, litres, or cubic feet determine how much material occupies the bed. Estimated weight helps with handling and vehicle limits, but soil density varies with composition, moisture, and compaction. A supplier's current product density and delivery rules are more reliable than a general planning profile.

Raised-bed soil also needs to suit the plants and drainage conditions. More volume does not correct an unsuitable mix, and an oversized compost fraction can create water-management or nutrient problems. Confirm the mix before using the order quantity as a purchasing decision.

How to Use This Tool:

Measure the inside footprint and the vertical gap that still needs soil, then add supplier rules only if you need a purchase plan.

Choose a rectangular, circular, or measured-area Bed footprint. Enter the dimensions in one unit and set Matching beds for identical beds only.
Enter the finished Target soil depth. In Advanced, add Existing soil depth when the bed is partly filled.
Select the closest Soil profile for a planning weight and set a Settlement allowance only when the job warrants one.
Enable Include supplier and handling plan to enter bag size, bulk minimum and increment, wheelbarrow capacity, prices, or vehicle payload. Use the supplier's quoted units.
Read Final order target in the Order worksheet. Then compare whole bags and the rounded bulk ticket in Delivery plan before choosing how to buy.

Interpreting Results:

Net fill is the physical void to be filled. Final order target adds the settlement allowance, so it is the relevant quantity for bag and bulk calculations. The Full target volume is useful for understanding the complete bed but should not be ordered again when existing soil receives credit.

Bag count, wheelbarrow loads, and vehicle trips are whole-number logistics estimates and always round upward. A bulk ticket is first raised to the supplier minimum and then to the next entered increment. Compare the purchased quantity with site storage and access, and verify estimated weight against the supplier and the vehicle's actual payload rating.

Technical Details:

Every shape becomes a footprint in square metres. A rectangle uses length times width, a circle uses its inside diameter, and a measured area is converted directly. The same footprint is then multiplied by the number of matching beds.

Formula Core

Existing soil is credited only up to the target depth. This prevents an overfilled bed from producing a negative fill volume.

d_{fill} = \max (d_{target} - \min (d_{existing}, d_{target}), 0)

The final volume multiplies footprint by fill depth and bed count, then applies the allowance percentage.

V_{order} = A \times d_{fill} \times n \times (1 + \frac{a}{100})

A is footprint area in m², d is depth in metres, n is the whole bed count, and a is the allowance percent. Estimated weight is order volume multiplied by the selected planning density. The available profiles use 1,200 kg/m³ for raised-bed mix, 1,280 kg/m³ for screened topsoil, and 1,600 kg/m³ for moist garden soil; these are planning values rather than product guarantees.

Ordering Rules

Rounding rules for bags, bulk tickets, handling loads, and vehicle trips
Quantity	Rule
Bag count	Final order volume ÷ bag volume, rounded upward.
Bulk ticket	Raise the exact bulk quantity to the entered minimum, then round upward to the next supplier increment.
Wheelbarrow loads	Final order volume ÷ entered capacity, rounded upward.
Vehicle trips	Estimated weight ÷ entered payload, rounded upward.

The calculation keeps full converted precision and rounds only for display and indivisible logistics quantities. Target depth must be greater than zero, bed count must be a whole number from 1 through 1,000, and allowance is limited to 0% through 40%. When supplier planning is enabled, bag size and bulk increment must be positive. A zero wheelbarrow capacity or vehicle payload leaves that count at zero rather than claiming a checked result.

Worked Examples:

Topping up two matching raised beds

Two beds measuring 2.4 m by 1.2 m have a combined footprint of 5.76 m². Raising the soil from 8 cm to a 20 cm target leaves a 12 cm fill depth, so net fill is 0.6912 m³. A 10% settlement allowance raises the order target to 0.76032 m³. With 40 L bags, the whole-bag order is 20 bags; a bulk supplier with a 0.5 m³ minimum and 0.25 m³ increments would issue a 1.0 m³ ticket.

References:

Raised bed gardens, University of Minnesota Extension.