Landscaping Calculator (Topsoil, Pavers, Plants)
Estimate topsoil volume, paver count, and plant count for any garden area split into lawn, paving, and planting zones.
Zone split (sum should be 100%)
How this works
We split the garden into three zones by percentage, then apply per-zone unit-rate rules:
lawnArea = garden × lawnPct / 100
topsoilM3 = lawnArea × 0.10 (100 mm depth)
pavingArea = garden × pavingPct / 100
paverCount = ceil(pavingArea / 0.0625) (250 × 250 mm)
plantArea = garden × plantsPct / 100
plantCount = ceil(plantArea / 1.5) (1 plant / 1.5 m²)If the three percentages don't sum to 100% we proportionally rescale them and surface the effective shares in the result panel. Negative inputs are clamped to zero.
Worked example
100 m² garden, 50% lawn, 25% paving, 25% plants:
- Lawn = 50 m² → 5 m³ topsoil
- Paving = 25 m² → ceil(25 / 0.0625) = 400 pavers
- Plants = 25 m² → ceil(25 / 1.5) = 17 plants
Sources
- British Standard BS 3882 (specification for topsoil) and field-practice landscape unit rates
FAQ
What if my zone percentages don't add up to 100?
The calculator clamps negative values to zero and then proportionally rescales the three shares so they sum to 100. If you enter 60-30-30 (which sums to 120) the effective shares become 50-25-25; if you enter 25-25-25 (which sums to 75) the effective shares become 33-33-33. The result panel shows the effective shares used. Pure all-zero input falls back to an equal one-third split so the rest of the math doesn't divide by zero.
Why is the lawn topsoil only 100 mm deep?
100 mm is the standard residential lawn rooting depth — enough for the typical Indian / Nepali lawn grasses (Bermuda, Zoysia, Kikuyu, St Augustine) to anchor and to retain moisture between irrigation cycles. For premium lawns or for soils with poor drainage, increase the depth to 150 mm and multiply the calculator's topsoil m³ by 1.5. For basic ground cover or weed-tolerant native grasses, 75 mm is acceptable — multiply by 0.75.
What size paver does the calculator assume?
250 × 250 mm — the most common size for residential garden paths and patios. Each paver covers 0.0625 m². For 300 × 300 mm pavers (more common for driveways) divide the calculator's paver count by 1.44; for 200 × 100 mm clay pavers (English bond) multiply by 3.125. The pavers-per-area formula scales linearly so any rectangular paver size can be back-figured from the calculator's output.
How is plant count derived from area?
We assume one plant per 1.5 m² — a typical mixed shrub-and-perennial spacing for residential beds. For tighter ground cover (annual flowers, low evergreens) use 1 plant per 0.5 m² (multiply count by 3). For ornamental shrubs (rose bushes, hibiscus) use 1 plant per 2.5 m² (multiply count by 0.6). Mature trees need much more space — 1 tree per 25–50 m² depending on species. Treat the calculator's count as the starting figure and adjust by zone type.
Does this account for hardscape edge restraint and drainage?
No. Procurement totals only. A real paving installation needs an edge restraint (concrete kerb or aluminium edging), 100–150 mm of compacted granular sub-base, and 40 mm of bedding sand below the pavers. For a 25 m² patio that adds about 4 m³ of base material and 1 m³ of sand. Lawns on heavy clay also need a French drain or sub-soil drainage system that this calculator does not size.
Can I exclude unpainted or unbuilt zones?
Set their percentages to zero. For example, a garden that is 60% lawn, 40% planting, and zero paving (no patio) gets the right answer with 60-0-40. The clamp-and-rescale logic preserves the relative shares of the non-zero zones, so this configuration produces a 60-0-40 split as expected.