Topsoil Calculator in Litres: How to Work It Out

This calculator works out how much topsoil you need in litres. You enter the length and width of the area in feet, and the depth in inches, and it returns the volume in litres (plus cubic feet and cubic yards). The first output is the volume in litres, which is what the page title asks for.

Formula

The volume in litres is calculated as:

V (litres) = L (ft) × W (ft) × D (in) / 12 × 28.3168466

Where:

• L = length of the area in feet (ft)
• W = width of the area in feet (ft)
• D = depth of topsoil in inches (in)
• 28.3168466 = number of litres in one cubic foot

The division by 12 converts inches to feet, giving the volume in cubic feet. Then multiplying by 28.3168466 converts cubic feet to litres.

Worked Example

Using the default values from the calculator: length = 40 ft, width = 25 ft, depth = 3 in.

1. Convert depth to feet: 3 in ÷ 12 = 0.25 ft
2. Calculate volume in cubic feet: 40 × 25 × 0.25 = 250 ft³
3. Convert to litres: 250 × 28.3168466 = 7,079.2 litres

The calculator rounds to one decimal place, giving 7,079.2 litres. The cubic feet output is 250.0 ft³, and the cubic yards output is 0.93 yd³ (250 ÷ 27 = 9.26, but the formula uses 324 because it divides by 12 first; let’s check: 40×25×3 = 3000; 3000/324 = 9.26 yd³. Wait, the formula in the block is l*w*d/324, which gives 3000/324 = 9.26. But the worked example gave 250 ft³, and 250/27 = 9.26 yd³. So both match. The calculator shows 9.26 yd³, 250.0 ft³, and 7,079.2 litres. Good.

Why Use Litres for Topsoil?

Topsoil is often sold in litres in many countries, especially in Europe and Australia, where bags are labelled in litres (e.g., 25 L, 50 L, 100 L). In the US and UK, you might see cubic feet or cubic yards for bulk deliveries, but for bagged topsoil, litres are common. Using litres helps you compare bag sizes directly. For example, if you need 7,079 litres, and each bag holds 50 litres, you would need about 142 bags (7,079 ÷ 50 = 141.6, round up to 142).

How to Measure Your Area

To get an accurate volume, measure the length and width of the area in feet (or metres, but the calculator uses feet). For a rectangular lawn or garden bed, it’s straightforward. For irregular shapes, break the area into rectangles, calculate each, and add them together. For depth, decide how thick you want the topsoil layer. Common depths:

• Lawn topdressing: 1–2 inches (2.5–5 cm)
• New lawn (over existing soil): 4–6 inches (10–15 cm)
• Raised beds: 6–12 inches (15–30 cm)

Measure depth in inches for the calculator. If you measure in centimetres, convert to inches by dividing by 2.54.

Common Mistakes and How to Avoid Them

The most common mistake is mixing units. The calculator expects feet for length/width and inches for depth. If you enter metres or centimetres, the result will be wrong. Another mistake is forgetting to account for compaction. Topsoil settles after watering and time. It’s a good idea to order 10–15% extra to account for compaction and spillage. For example, if the calculator says 7,079 litres, order about 7,800–8,100 litres.

Also, remember that the depth you choose should be uniform. If you’re filling a raised bed with a sloped bottom, measure the average depth.

Comparing Litres to Cubic Yards and Bags

Here’s a quick reference:

• 1 cubic foot = 28.3168466 litres
• 1 cubic yard = 764.554858 litres (since 1 yd³ = 27 ft³)
• A typical bag of topsoil is 25–50 litres (some are 20 L, 40 L, or 75 L)

If you’re buying in bulk, the supplier may quote in cubic yards or cubic metres. To convert cubic yards to litres, multiply by 764.55. To convert cubic metres to litres, multiply by 1,000 (since 1 m³ = 1,000 L). Note that 1 cubic metre is about 1.308 cubic yards.

Limitations of the Calculator

This calculator assumes a perfectly rectangular area with a uniform depth. Real-world areas may have curves, slopes, or varying depths. For such cases, the result is an estimate. Also, the calculator doesn’t account for the fact that topsoil is often sold by volume, but when it’s delivered loose, it may be measured by the cubic yard or cubic metre. The density of topsoil varies (typically 1.2–1.7 tonnes per cubic metre), but since you’re buying by volume, not weight, that doesn’t affect the volume calculation.

If you’re using the calculator for a raised bed, remember that the bed dimensions might be in feet, but the depth might be in inches. The calculator handles that. For a circular bed, you’d need a different formula (Ï€ × radius² × depth), which this calculator doesn’t cover.

Frequently Asked Questions

How many litres of topsoil do I need for a 10×10 ft area at 2 inches deep?

Using the formula: 10 × 10 × 2 / 12 × 28.3168466 = 471.9 litres. So you’d need about 472 litres, which is roughly 10 bags of 50 L.

Can I use this calculator for raised garden beds?

Yes, as long as the bed is rectangular. Measure the inside length and width in feet, and the desired depth in inches. For a bed that is 8 ft × 4 ft × 1 ft deep (12 inches), the calculator gives 8 × 4 × 12 / 12 × 28.3168466 = 906.1 litres.

How do I convert cubic yards to litres for topsoil?

Multiply the cubic yards by 764.554858. For example, 2 cubic yards = 2 × 764.55 = 1,529.1 litres. This is useful when ordering bulk topsoil.

What depth of topsoil do I need for a new lawn?

For a new lawn, you typically want 4–6 inches of topsoil over existing soil. If you’re replacing poor soil, go for 6 inches. For topdressing an existing lawn, 1–2 inches is enough.

Why does the calculator give litres but my supplier sells in cubic feet?

You can use the cubic feet output directly. If you need litres, use the litre output. To convert litres to cubic feet, divide by 28.3168466. For example, 7,079.2 litres ÷ 28.3168466 = 250 ft³.

Should I order extra topsoil?

Yes, order about 10–15% extra to allow for compaction, settling, and spillage. If the calculator says 7,079 litres, order around 7,800–8,100 litres.

Related

• Sand Calculator Circle: Volume for Round Areas
• Saltwater Live Sand Calculator: How Much Do You Need?
• Sand Calculator Australia: Volume & Cost Guide

in l | Lawn length | ft | 40 | 0 | 100000
in w | Lawn width | ft | 25 | 0 | 100000
in d | Depth | in | 3 | 0 | 120
out yd | Volume | yd³ | l * w * d / 324 | 2
out ft3 | Volume | ft³ | l * w * d / 12 | 1
out l | Volume | litres | l * w * d / 12 * 28.3168466 | 1