Free Tool · Calculators

Topsoil & Top Dressing Calculator

Enter the area's length, width, and how deep you want to cover it — get the total volume plus how many standard 25L bags to pick up, or when bulk delivery makes more sense. Imperial and metric.

Topsoil needed
Cubic yards
Cubic metres
25L bags
Recommendation

This tool gives estimates for planning purposes only and isn’t a substitute for professional measurement, a site inspection, or your local building code and supplier guidance. Always verify quantities and code requirements before purchasing materials or beginning work.

How this is calculated

Volume is simply length × width × depth — the trick is keeping units consistent, since depth is almost always specified in inches or centimetres while area is in feet or metres. This tool converts everything to a common unit, applies your settling factor, then converts the result to cubic yards, cubic metres, and a practical bag count.

Worked example: a 20 × 10 ft area top-dressed 2 inches deep: volume = 20 × 10 × (2/12) = 33.3 ft\u00B3. Add 10% settling → 36.7 ft\u00B3 ≈ 1.36 yd\u00B3 ≈ 1.04 m\u00B3 → about 42 bags of 25L topsoil, well past the point where bulk delivery is the better call.

Bagged vs. bulk — the crossover point

One cubic yard ≈ 764.6 litres ≈ 31 bags of 25L soil. Bagged soil typically costs 2–3× more per litre than bulk, but bulk requires a delivery drop zone and moving it by wheelbarrow. As a rule of thumb: under roughly 15–20 bags (about 0.5 yd\u00B3), bagged is usually more convenient; above that, call for bulk delivery.

Common mistakes

How much topsoil do I need for a lawn top dressing?

Lawn top dressing is typically 1/4–1/2 inch (6–13 mm) deep. Enter your lawn's length and width with that depth to get exact volume — most residential lawns need well under a cubic yard for a single top dress.

How many 25L bags of topsoil equal a cubic yard?

One cubic yard is about 764.6 litres, or roughly 31 bags of 25L topsoil. Bags are convenient and cost more per litre than bulk; once you're past about 15–20 bags (roughly 0.5 yd\u00B3), bulk delivery is almost always cheaper and less carrying.

What thickness should I use for a new lawn vs top dressing?

New lawn / seed bed: 2–4 inches (5–10 cm) of topsoil over the graded area. Top dressing an established lawn: 1/4–1/2 inch (6–13 mm) so grass isn't smothered. Garden beds: 4–6 inches (10–15 cm) is common.

Should I account for settling or compaction?

Yes \u2014 loose topsoil settles roughly 10–20% after watering and time. This calculator's default 10% waste/settling factor covers typical cases; increase it for loose, fluffy soil or if you're grading a large area.

Is bagged or bulk topsoil better value?

Bulk (by the yard/cubic metre, delivered loose) is cheaper per volume once you need more than roughly half a yard, but requires a driveway drop spot and a wheelbarrow. Bagged is easier for small jobs, raised beds, or when you can't have a pile delivered.