Overview
Sands are chosen by job: sharp sand beds and blends, building sand makes mortar, kiln-dried sand joints block paving.
How the calculation works
Sand tonnage = area × depth × planning density, with the depth in metres — 50mm of bedding sand over 20 m² is 1.0 m³.
Sharp sand at 1.6 t/m³ makes that 1.6 tonnes; building sand at 1.5 t/m³ would be 1.5 tonnes. The density difference matters at bulk-bag scale.
For screeds and mortars the same engine applies: enter the area and finished thickness and select the sand type.
Worked example
Block paving 30 m² needs a 50mm sharp sand bedding course.
Volume = 30 × 0.05 = 1.5 m³. Weight = 1.5 × 1.6 = 2.4 tonnes.
A 10% allowance takes the order to 2.64 tonnes — four 850kg bulk bags (2,640kg needs four bags; three would leave you roughly 90kg short).
Sharp sand at a glance
- Planning density1.60 t/m³
- Typical range1.50–1.70 t/m³
- CategorySand
- CompactionUsually not applied
- SourcePlanning value based on typical UK sharp sand bulk densities
- Reviewed2026-08-16
Planning values for typical UK supplies; your supplier product data takes precedence.
Sharp sand coverage guide
| Depth | Area per tonne | Area per 850kg bag | Weight per m² |
|---|---|---|---|
| 25mm | 25.0 m² | 21.3 m² | 40 kg |
| 40mm | 15.6 m² | 13.3 m² | 64 kg |
| 50mm | 12.5 m² | 10.6 m² | 80 kg |
| 75mm | 8.3 m² | 7.1 m² | 120 kg |
| 100mm | 6.3 m² | 5.3 m² | 160 kg |
| 150mm | 4.2 m² | 3.5 m² | 240 kg |
Computed from a 1.60 t/m³ planning density on level ground.
Assumptions and accuracy
Planning densities assume typical UK bulk supplies; kiln-dried sand in 25kg bags behaves consistently, while bulk sand varies with moisture.
Wet sand can weigh 15-20% more per cubic metre than dry sand for the same grading.
Quantities for mortar and concrete also need cement — see the ballast calculator for mix-based jobs.
Planning density values
Use supplier product data whenever available. These figures are planning defaults shared by every calculator on the site.
| Material | Category | Planning density | Typical range | Compaction |
|---|---|---|---|---|
| MOT Type 1 | Sub Base | 2.20 t/m³ | 2.00–2.30 t/m³ | Relevant |
| MOT Type 3 | Sub Base | 2.10 t/m³ | 1.90–2.20 t/m³ | Relevant |
| Recycled Type 1 | Recycled | 2.00 t/m³ | 1.80–2.20 t/m³ | Relevant |
| 6F2 / 6F5 crushed aggregate | Recycled | 2.00 t/m³ | 1.80–2.20 t/m³ | Relevant |
| Road planings | Recycled | 2.00 t/m³ | 1.80–2.20 t/m³ | Relevant |
| Sharp sand | Sand | 1.60 t/m³ | 1.50–1.70 t/m³ | Usually no |
| Building sand | Sand | 1.50 t/m³ | 1.40–1.60 t/m³ | Usually no |
| Kiln-dried sand | Sand | 1.50 t/m³ | 1.40–1.60 t/m³ | Usually no |
| 10mm pea shingle | Gravel | 1.60 t/m³ | 1.40–1.70 t/m³ | Usually no |
| 20mm gravel / shingle | Gravel | 1.60 t/m³ | 1.40–1.70 t/m³ | Usually no |
| Decorative gravel | Decorative | 1.50 t/m³ | 1.30–1.70 t/m³ | Usually no |
| Slate chippings | Decorative | 1.60 t/m³ | 1.40–1.80 t/m³ | Usually no |
| Gabion stone | Gravel | 1.50 t/m³ | 1.40–1.60 t/m³ | Usually no |
| Self-binding gravel | Gravel | 1.90 t/m³ | 1.80–2.10 t/m³ | Relevant |
| Crushed concrete | Recycled | 1.90 t/m³ | 1.70–2.10 t/m³ | Relevant |
| Limestone scalpings | Sub Base | 2.00 t/m³ | 1.80–2.20 t/m³ | Relevant |
| Ballast | Sand | 1.70 t/m³ | 1.60–1.80 t/m³ | Usually no |
| Generic aggregate | General | 1.70 t/m³ | 1.50–2.20 t/m³ | Usually no |
How to use this calculator
- Measure the paved or screeded area.
- Enter the sand layer thickness — commonly 50mm for block bedding, 25-50mm for screeds depending on design.
- Select the sand type you are ordering.
- Add 5-10% allowance for levelling losses at edges.
When sand is commonly used
Sharp sand beds block paving and slabs, and forms screeds and concrete when blended with cement; building sand is the soft sand for bricklaying mortar; kiln-dried sand is brushed into block joints to lock the surface.
Frequently asked questions
How much sand do I need for block paving?
Allow a 50mm compacted sharp sand bedding course: about 0.05 m³ (80kg) per square metre. A 30 m² driveway therefore needs roughly 2.4 tonnes plus allowance.
How many m² does a bulk bag of sand cover?
An 850kg bulk bag of sharp sand is about 0.53 m³, covering around 10.6 m² at a 50mm bedding depth.
Sharp sand or building sand?
Sharp (gritted) sand is for bedding paving and mixing concrete or screed; building (soft) sand is for mortar. Using soft sand under paving leads to movement — see the sharp sand calculator for the bedding case.
How much kiln-dried sand for block paving joints?
As a planning figure, one 25kg bag of kiln-dried sand joints roughly 15–20 m² of standard 50mm blocks after brushing in. Wider or deeper joints need proportionally more.
References and source notes
- Typical UK sand bulk densities from supplier technical data (planning values).