Soil Calculator
Measure a bed or an area, pick a fill depth, and get the soil volume in cubic metres and cubic yards along with weight, bag count and an estimated bulk delivery cost.
🌱 What is a Soil Calculator?
A soil calculator converts the physical size of a garden bed or an area of ground into the amount of soil you actually have to buy. It takes a footprint, either a length times a width or the area of a circle, multiplies it by the depth you want to fill, and reports the answer as a volume. Because bulk soil is quoted per cubic metre in most of the world and per cubic yard in North America, and because it is delivered by weight rather than by volume, the same job needs three different numbers before you can place an order with confidence.
Gardeners reach for this most often when filling new raised beds, when topdressing a lawn or a border with a thin layer of screened topsoil, and when levelling a patch of ground before laying turf or sowing seed. Landscapers use it in reverse, to check that a quoted delivery is the right size for the job. Allotment holders use it to decide whether a project is a bagged-soil job or a bulk-delivery job, since the crossover point is usually somewhere near half a cubic metre.
The most common misconception is that soil quantities scale gently with depth. They do not. Volume is directly proportional to depth, so doubling a bed from 15 cm to 30 cm doubles both the cost and the delivered weight, and a bed that seemed like a manageable weekend job at 15 cm becomes a two tonne delivery at 30 cm. The second misconception is treating volume and weight as interchangeable. A cubic metre of light compost blend and a cubic metre of stony subsoil occupy the same space but can differ by nearly a tonne, which is why bulk density is an input here rather than a fixed constant.
This calculator handles rectangular beds, open areas and round planters, repeats the figure across as many identical beds as you have, and then presents the result four ways: as volume in cubic metres and cubic yards, as weight in tonnes, as a count of 40 litre bags, and as an estimated cost at your supplier's rate. The depth comparison table underneath shows all of those figures across eight common fill depths at once, so you can see immediately what trimming a bed from 25 cm to 20 cm saves you. For containers, tapered pots and nursery-style potting mixes, use the potting soil calculator instead, which is built around container volumes rather than bulk ground coverage.
📐 Formula
📖 How to Use This Calculator
Steps
💡 Example Calculations
Example 1 — One Standard Raised Bed
3 m × 1.2 m bed, filled 15 cm deep, topsoil at 1300 kg/m³ and 40 per m³
Example 2 — Four Deep Vegetable Beds
Four beds of 2.4 m × 1.2 m, each filled 25 cm deep for root crops
Example 3 — Two Round Planters
Two circular beds 1.5 m across, filled 30 cm deep
Example 4 — Topdressing an Open Lawn Area
10 m × 8 m lawn, 5 cm of screened topsoil at 1400 kg/m³ and 35 per m³
❓ Frequently Asked Questions
🔗 Related Calculators
How much soil do I need for a raised bed?
Multiply the bed length by the width to get the area, then multiply by the fill depth in metres. A 3 m by 1.2 m bed filled 15 cm deep is 3.6 m² times 0.15 m, which is 0.54 cubic metres, or about 0.71 cubic yards. That is roughly 14 bags of 40 litres, or a little over 700 kg of moist topsoil.
What is the formula for soil volume?
Volume equals area times depth times the number of beds. For a rectangular bed, area is length times width. For a round bed, area is pi times the radius squared. Keep depth in the same unit as the area, so a depth entered in centimetres is divided by 100 before multiplying.
How many cubic yards is one cubic metre of soil?
One cubic metre is 1.308 cubic yards, and one cubic yard is 0.7646 cubic metres. Bulk soil in North America is normally quoted per cubic yard, so a 2 cubic metre order is about 2.62 cubic yards. This calculator shows both figures so you can read the number your supplier quotes in.
How much does a cubic metre of topsoil weigh?
Moist screened topsoil is commonly 1200 to 1400 kg per cubic metre, so a cubic metre weighs a little over a tonne. Sandy or stony soil is heavier, near 1500 to 1700 kg, while compost-rich or peat-based blends can be 800 to 1000 kg. Wet soil after rain can weigh 20 percent more than the same soil dry.
How many 40 litre bags make a cubic metre?
Exactly 25, because one cubic metre is 1000 litres. That is why bulk delivery is usually much cheaper for anything above roughly half a cubic metre. The calculator rounds the bag count up, since you cannot buy a partial bag.
Should I use topsoil or a raised bed mix?
Straight topsoil compacts in a raised bed and drains poorly. A common approach is roughly 60 percent screened topsoil, 30 percent compost and 10 percent coarse material such as grit or bark fines. Order the total volume from this calculator, then split it between those components.
How deep should soil be in a vegetable bed?
Most vegetables are happy with 20 to 30 cm of good soil. Salad leaves, radish and herbs will crop in 15 cm. Carrots, parsnips and potatoes want 30 cm or more. If your bed sits on open ground rather than a hard surface, roots can travel below the frame, so the bed itself can be shallower.
Does this calculator work for containers and pots?
It works for anything you can describe as an area times a depth, so a large square planter is fine. For tapered pots, nursery containers and hanging baskets, the potting soil calculator is a better fit because it handles container shapes and potting mix densities rather than bulk topsoil.
How much extra soil should I order for settling?
Add 5 to 10 percent. Freshly delivered bulk soil holds air pockets that collapse the first time the bed is watered thoroughly or gets heavy rain. Beds filled with a high proportion of compost settle more, sometimes 15 percent, because the organic fraction continues to break down.
How do I calculate soil for an irregular shaped bed?
Break the shape into rectangles and circles, run each piece through the calculator separately, then add the volumes. For a rough curved border, measure the average width along its length and treat it as a rectangle, which is accurate to within a few percent for most garden shapes.
What is bulk density and why does it matter?
Bulk density is the mass of soil per unit of total volume, including the pore spaces between particles. It converts the volume you ordered into the weight that arrives on the truck, which matters for delivery limits, for barrow trips, and for checking whether a first floor terrace can take the load.
How many wheelbarrow loads is a cubic metre of soil?
A standard builder's barrow holds about 85 litres heaped, so a cubic metre is roughly 12 full barrow loads. Most people load nearer 65 litres to keep the barrow manageable when the soil is wet, which pushes it closer to 15 loads per cubic metre.