Sand Calculator - Volume, Tonnes & Bags
Calculate Sand for UK Construction & Landscaping Projects
Whether you're laying paving, mixing mortar, screeding floors, or creating a children's sandpit, this calculator helps you determine exactly how much sand you need. Simply enter your dimensions and select your sand type to get accurate results in tonnes, cubic metres, and 25kg bags.
This calculator uses UK industry-standard densities and includes wastage recommendations to ensure you order the right amount first time.
Measure across the widest point of your circular area
Tip: For irregular shapes, divide into rectangles and triangles, calculate each area, then add them together.
UK Sand Types Explained
Choosing the correct sand type is crucial for your project's success. Using the wrong sand can lead to structural failures, drainage problems, or safety hazards.
Building Sand (Soft Sand)
Density: 1.5-1.7 tonnes/m³ (avg 1.6)
Grain size: Fine, rounded particles
Colour: Yellow, golden, or red
Best for: Mortar, rendering, bricklaying, plastering, pointing
Sharp Sand (Grit Sand)
Density: 1.6-1.8 tonnes/m³ (avg 1.7)
Grain size: Coarse, angular particles
Colour: Grey or brownish
Best for: Concrete, paving beds, drainage, floor screeds, mixing with cement for slabs
Play Sand (Kiln-Dried)
Density: 1.4-1.6 tonnes/m³ (avg 1.5)
Grain size: Very fine, smooth, rounded
Standard: BS EN 71-3 certified
Best for: Sandpits, play areas, golf bunkers, equestrian arenas
Silver Sand (Horticultural)
Density: 1.6-1.7 tonnes/m³ (avg 1.65)
Grain size: Fine, uniform particles
Colour: Light grey/silver
Best for: Lawn top-dressing, seed propagation, aquarium substrates, artificial grass infill
Common Sand Mistakes to Avoid
- Never use sharp sand for mortar - it won't bond properly and will crack
- Never use building sand for concrete - it lacks the strength needed
- Never use builder's sand in sandpits - it may contain harmful substances
- Don't use beach sand - salt content damages mortar and concrete
- Avoid contaminated sand - check for clay, silt, or organic matter
Sand Calculation Formulas
Rectangular Areas
Volume = L × W × D
L = Length, W = Width, D = Depth (metres)
Circular Areas
Volume = π × r² × D
r = radius (diameter ÷ 2), D = Depth
Weight (tonnes) = Volume (m³) × Density (t/m³)
Worked Example
Project: Paving base for patio - 4m × 3m at 40mm depth using sharp sand
1. Convert depth: 40mm ÷ 1000 = 0.04m
2. Calculate volume: 4m × 3m × 0.04m = 0.48m³
3. Calculate weight: 0.48m³ × 1.7 t/m³ = 0.816 tonnes
4. Add 10% wastage: 0.816 × 1.1 = 0.90 tonnes
5. Convert to bags: 0.90 × 1000 ÷ 25 = 36 bags (25kg each)
Recommended Sand Depths for UK Projects
| Application | Sand Type | Depth | Notes |
|---|---|---|---|
| Block paving bed | Sharp sand | 25-40mm | Over compacted MOT Type 1 sub-base |
| Patio slab bedding | Sharp sand | 30-50mm | Mix 6:1 with cement for mortar bed |
| Floor screed | Sharp sand | 25-75mm | Mix 3:1 or 4:1 with cement |
| Children's sandpit | Play sand | 150-300mm | Must be BS EN 71-3 certified |
| Pipe bedding | Sharp sand | 50-100mm | Below and around drainage pipes |
| Jointing (between pavers) | Kiln-dried sand | Brush in | Fill joints to 3-5mm from surface |
| Lawn top-dressing | Silver sand | 3-6mm | Mix with loam and compost |
| Artificial grass infill | Kiln-dried/Silver | 5-10kg/m² | Helps fibres stand upright |
Sand Coverage Quick Reference
Use this table to quickly estimate how much area one tonne of sand will cover at different depths.
| Depth | Building Sand (1.6 t/m³) | Sharp Sand (1.7 t/m³) | Play Sand (1.5 t/m³) |
|---|---|---|---|
| 25mm | 25.0m² per tonne | 23.5m² per tonne | 26.7m² per tonne |
| 30mm | 20.8m² per tonne | 19.6m² per tonne | 22.2m² per tonne |
| 40mm | 15.6m² per tonne | 14.7m² per tonne | 16.7m² per tonne |
| 50mm | 12.5m² per tonne | 11.8m² per tonne | 13.3m² per tonne |
| 75mm | 8.3m² per tonne | 7.8m² per tonne | 8.9m² per tonne |
| 100mm | 6.3m² per tonne | 5.9m² per tonne | 6.7m² per tonne |
Mortar & Concrete Mixing Ratios
Use these standard UK mixing ratios for common construction applications. Always use building sand for mortar and sharp sand for concrete.
Mortar Mixes (Building Sand + Cement)
| Class | Ratio (Sand:Cement) | Application |
|---|---|---|
| M2 (Weak) | 6:1 | Internal walls, non-load bearing partitions |
| M4 (General) | 5:1 | General purpose brickwork, above DPC |
| M6 (Strong) | 4:1 | Engineering bricks, below DPC, retaining walls, exposed areas |
| Render (First coat) | 4:1 | Scratch coat for external render |
| Render (Top coat) | 5:1 or 6:1 | Finish coat for external render |
Concrete Mixes (Sharp Sand + Aggregate + Cement)
| Mix Type | Ratio (Cement:Sand:Aggregate) | Application |
|---|---|---|
| C15 (Gen 1) | 1:2:4 | Foundations for garden walls, light footings |
| C20 (Gen 2) | 1:2:3 | Shed bases, fence posts, general foundations |
| C25 (ST 2) | 1:1.5:2.5 | House foundations, driveways, floor slabs |
| Screed | 1:3 or 1:4 (sand:cement only) | Floor screeds, levelling compound |
Pro Tips for Mixing
- Add plasticiser to mortar for improved workability and frost resistance
- Mix dry ingredients first before adding water gradually
- Consistency check: Mortar should hold its shape when squeezed without crumbling
- Don't over-wet - too much water weakens the mix
- Work quickly - mortar starts setting in 30-60 minutes
UK Sand Prices 2024-2025
Current sand prices vary by region and supplier. Prices include VAT but exclude delivery.
Building Sand
£45-65 per tonne (bulk)
Bulk bag (850kg): £45-70
25kg bag: £3-5
Sharp Sand
£40-60 per tonne (bulk)
Bulk bag (850kg): £40-65
25kg bag: £3-4.50
Play Sand
£60-100 per tonne
Bulk bag (850kg): £60-90
25kg bag: £4-7
Delivery Costs
Bulk loads: £30-80
Distance-dependent pricing
Free delivery often over £100
Money-Saving Tips
- Bulk is cheaper: 1 tonne delivered costs less than 40 individual 25kg bags
- Combine orders: Add sand to aggregate deliveries to save on delivery fees
- Compare suppliers: Prices vary significantly - get 3+ quotes for large orders
- Collect yourself: Many builders' merchants offer cheaper collection prices
Where to Buy Sand in the UK
Builders' Merchants
- Travis Perkins
- Jewson
- Buildbase
- MKM Building Supplies
- Selco
DIY Stores
- B&Q
- Wickes
- Homebase
- Screwfix (collection)
- Toolstation
Aggregate Suppliers
- Breedon Group
- Tarmac
- Aggregate Industries
- Hanson
- Local quarries
Online Suppliers
- Gravelmaster
- Decorative Aggregates
- DERA UK
- Amazon (small quantities)
- eBay (bulk bags)
How to Store Sand Correctly
Proper storage ensures your sand stays usable and maintains its quality for mixing.
Do
- Store on a hard, level surface (pallet or tarpaulin)
- Cover with waterproof sheeting
- Keep away from trees (leaves contaminate)
- Use within 3 months for best results
- Drain bulk bags to prevent waterlogging
Don't
- Store directly on grass or soil
- Leave uncovered in rain
- Mix different sand types together
- Store near cement (absorbs moisture)
- Use contaminated or mouldy sand
Wet Sand Warning
Wet sand weighs significantly more than dry sand and won't mix properly with cement. If your sand gets wet, let it drain thoroughly before use. Saturated sand can weigh up to 2.0 tonnes/m³ compared to 1.6 tonnes/m³ when dry. This affects both handling and mixing ratios.
Frequently Asked Questions
How much sand do I need for my project?
+To calculate sand needed: Length (m) × Width (m) × Depth (m) = Volume in cubic metres. Then multiply by the sand density (typically 1.5-1.7 tonnes per m³ depending on type). For example, a 5m × 3m area at 50mm depth needs 0.75m³ or approximately 1.2 tonnes of building sand. Always add 10% for wastage and compaction.
What is the difference between building sand and sharp sand?
+Building sand (soft sand) has fine, rounded grains and is used for mortar, rendering, and bricklaying. Sharp sand (grit sand) has coarser, angular grains and is used for concrete mixes, paving, drainage, and screeding. Sharp sand provides better drainage and structural strength, while building sand gives smoother, more workable mortar. Never use sharp sand for mortar or building sand for concrete.
How many 25kg bags of sand do I need?
+One tonne of sand equals 40 bags of 25kg each. One cubic metre of sand weighs approximately 1.5-1.7 tonnes, so you'd need 60-68 bags per cubic metre. For small areas: 1m² at 50mm depth needs approximately 4-5 bags of 25kg sand. Bulk delivery is more economical for quantities over 0.5 tonnes.
How much does sand cost in the UK in 2024-2025?
+UK sand prices in 2024-2025: Building sand costs £45-65 per tonne bulk delivered, or £3-5 per 25kg bag. Sharp sand costs £40-60 per tonne bulk delivered, or £3-4.50 per 25kg bag. Play sand (kiln-dried) costs £60-100 per tonne, or £4-7 per 25kg bag. Delivery typically adds £30-80 depending on distance and quantity.
What depth of sand do I need for paving?
+For block paving, use 25-40mm of sharp sand as a laying course over a compacted MOT Type 1 sub-base. For patio slabs, use 30-50mm of sharp sand mixed with cement (6:1 ratio) for a solid bed. For jointing between pavers, use kiln-dried sand brushed into the gaps. Never exceed 50mm depth for laying course as it may cause uneven settling.
What is the correct sand to cement ratio for mortar?
+Standard mortar ratios using building sand: General purpose (Class M4): 5 parts sand to 1 part cement. Strong mix (Class M6): 4 parts sand to 1 part cement - for engineering bricks, below DPC, or exposed areas. Weak mix (Class M2): 6 parts sand to 1 part cement - for internal non-load bearing walls. Adding plasticiser improves workability and frost resistance.
How much area does one tonne of sand cover?
+One tonne of sand covers approximately: 12-14m² at 50mm depth, 16-20m² at 40mm depth, 20-25m² at 30mm depth, or 25-33m² at 25mm depth. Coverage varies slightly by sand type - sharp sand covers slightly more area per tonne than building sand due to its coarser texture.
Can I use any sand for a children's sandpit or play area?
+No - only use certified play sand for sandpits and children's play areas. Play sand is washed, kiln-dried, and tested to BS EN 71-3 safety standards to ensure it's free from harmful substances, bacteria, and sharp particles. Building sand and sharp sand contain impurities and are NOT safe for children. Quality play sand costs more but is essential for child safety. Depth should be 150-300mm for effective play.
Last Updated: December 2025 | Prices and densities based on UK market data
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