How do I calculate how much topsoil I need?

Multiply length (m) × width (m) × depth (m) to get volume in cubic metres. For example, a 4m × 2m garden bed at 20cm depth = 4 × 2 × 0.20 = 1.6 m³. Always add 10% for settling and waste.

How much does topsoil cost in South Africa?

In 2026, bulk topsoil costs approximately R300–R600/m³ delivered. Compost costs R400–R800/m³. Retail 30-litre bags of potting mix cost R80–R120 per bag (equivalent to R2,700–R4,000/m³). Bulk delivery is far more economical for quantities over 1m³.

How deep should I put topsoil in my garden?

Recommended soil depths: lawn 100mm (10cm), ground cover and annuals 150mm, flower beds 200mm, shrubs and roses 300mm, vegetable gardens 300mm, deep-rooted vegetables like carrots 450mm. More depth means better plant establishment and yield.

What is the difference between topsoil and compost?

Topsoil is the natural upper layer of soil used for planting and filling. Compost is decomposed organic matter that improves soil structure, drainage, and nutrients. Most gardeners mix 70% topsoil with 30% compost for optimal growing conditions. Pure compost can be too rich for some plants.

How many 30L bags of soil do I need per square metre?

At 20cm (200mm) depth, you need 200L of soil per m², which is approximately 7 bags of 30L. At 30cm depth, you need 10 bags per m². For large areas, bulk delivery by the cubic metre is more economical — a 5m³ delivery truck covers approximately 25 m² at 20cm depth.

Soil & Topsoil Calculator South Africa

Calculate how much topsoil, compost, or potting mix you need for your garden beds and landscaping projects in South Africa. Get volume, weight, bag counts, and cost estimates.

⚡ Quick Calculator Get a fast estimate

Length (m)

Width (m)

Depth (cm)

Lawn: 10cm | Flower beds: 20cm | Veggie gardens: 30cm

Soil Type

Volume Required

1.600 m³

Weight (tonnes)

1.76 t

30L Bags Needed

54 bags

Estimated Cost

R 480 – R 960

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How to Use the Soil Calculator

Enter your garden area's length and width in metres and the depth in centimetres. Select the soil type — topsoil, compost, or potting mix. The calculator shows volume in m³, weight, 30L bag count, and estimated cost in ZAR.

Volume (m³) = Length × Width × (Depth ÷ 100) Weight (tonnes) = Volume × Density 30L bags = Volume × 1,000 ÷ 30

The Extended Calculator handles multiple beds with different shapes. The Professional Calculator includes soil amendment mixing ratios and recommended depths by plant type.

Need more detail?

📊 Extended Calculator More options, charts, and scenario comparison

Garden Beds

Raised Bed

Shape

Length (m)

Width (m)

Soil Depth (cm)

Soil Type

Soil volume: 0.960 m³

Total Soil Required

0.960 m³

Estimated Cost

R 288 – R 576

Bed 1

0.960 m³ (32 × 30L bags)

Garden bed visualization — size relative to largest bed

Soil Types Used in South African Gardens

Type	Best For	Bulk Price (2026)	Density
Topsoil	Lawn establishment, general fill, raised beds	R300–R600/m³	1.1 t/m³
Compost	Soil amendment, mulching, vegetable gardens	R400–R800/m³	0.6 t/m³
Potting Mix	Container plants, seedlings, indoor plants	R80–R120 / 30L bag	0.4 t/m³
Lawn Dressing	Lawn levelling and feeding	R250–R450/m³	0.8 t/m³

Recommended Soil Mixing Ratios

For best results in different garden types:

Lawn: 100% topsoil or lawn dressing at 100mm depth

Flower Beds: 70% topsoil + 30% compost at 200mm depth

Vegetable Gardens: 60% topsoil + 40% compost at 300mm depth (or pure compost for intensive beds)

Container Plants: 30% topsoil + 30% compost + 40% potting mix

Raised Beds: 50% topsoil + 50% compost for excellent drainage and nutrition

Bulk vs Bags: Which is More Economical?

For quantities above 0.5 m³ (about 17 bags of 30L), bulk delivery is almost always more cost-effective. A 30L bag of topsoil at R50 retail equals approximately R1,667/m³ — 3–5× more expensive than bulk prices of R300–R600/m³.

Most SA suppliers deliver from 1 m³ minimum in a small bakkie, and 3–6 m³ by tipper truck. Delivery fees in Gauteng and Western Cape typically range from R200–R500 within 30km.

Need full precision?

🔬 Professional Calculator Complete parameters, sensitivity analysis, and detailed breakdown

Waste / Over-order Factor (%)

Recommended 10%

Garden Beds & Soil Mix

Bed Name	Area (m²)	Depth (cm)	Topsoil %	Compost %	Potting %

Total Garden Project Soil Budget

R 1 743 – R 3 286

Total Volume

4.15 m³

Topsoil needed

2.64 m³ (R 792–R 1 584)

Compost needed

1.38 m³ (R 551–R 1 102)

Potting Mix (30L bags)

5 bags (R 400–R 600)

Delivery Loads (5m³)

1 load

Recommended Soil Depths by Plant Type

Plant Type	Min Depth	Notes
Lawn / Grass	100mm	10cm topsoil minimum
Ground Cover & Annuals	150mm	15cm for shallow-rooted plants
Flower Beds	200mm	20cm standard for perennials
Shrubs & Roses	300mm	30cm for established root systems
Vegetable Gardens	300mm	30cm deep for most vegetables
Deep-Rooted Veggies	450mm	45cm for carrots, parsnips, beetroot
Trees (young)	600mm	60cm to 1m for tree establishment

Frequently Asked Questions — Soil Calculator SA

Multiply length × width × depth (all in metres). For a 4m × 2m bed at 20cm: 4 × 2 × 0.20 = 1.6 m³. Add 10% for settling. Our calculator does this instantly and converts to weight and 30L bag counts.

2026 South African bulk soil prices: topsoil R300–R600/m³; compost R400–R800/m³; potting mix R80–R120 per 30L bag. Retail bags are 3–5× more expensive per m³ than bulk delivery. For areas over 0.5 m³, bulk delivery saves significantly.

Recommended depths: lawn 100mm (10cm); flower beds 200mm; vegetable gardens 300mm; deep-rooted vegetables 450mm; young trees 600mm+. More depth means better water retention and stronger root development, especially in SA's hot summers.

Topsoil is the natural mineral-rich upper soil layer used for volume filling. Compost is decomposed organic matter that feeds soil biology and improves structure. Mixing 70% topsoil with 30% compost creates an ideal growing medium for most SA gardens.

At 10cm depth: ~3.3 bags per m². At 20cm: ~6.7 bags per m². At 30cm: ~10 bags per m². For a 4×2m veggie bed at 30cm depth, that's about 80 bags — bulk delivery makes far more sense at this scale.