Formula Used
First, the calculator finds each bed's surface area. It multiplies area by the effective filling depth. Shape formulas support common and custom garden bed layouts.
Allowances increase the base material volume sequentially. Soil percentages then divide the adjusted mixture volume. Density converts the final sand volume into estimated weight.
Base volume = Bed area × Effective depth × Unoccupied fraction Adjusted volume = Base volume × (1 + compaction) × (1 + settlement) × (1 + waste) Sand volume = Adjusted volume × Sand percentage Sand weight = Sand volume × Effective density Bags required = Required weight or volume ÷ Bag capacity
How to Use the Calculator
Select the garden bed shape and measurement units. Enter dimensions for one bed and its quantity. Use custom area when the layout is irregular.
Choose a depth method or suitable preset. Add freeboard and occupied material when they apply. Enter allowances that match your site and handling conditions.
Select the sand type and moisture condition. Add packaging, delivery, and current supplier prices. Review quantities before ordering or scheduling any delivery.
Example Data
| Input | Example value | Purpose |
|---|---|---|
| Bed dimensions | 3 m × 1.2 m | Defines surface area |
| Additional depth | 5 cm | Defines the sand layer |
| Compaction | 10% | Covers volume reduction |
| Settlement | 5% | Covers later sinking |
| Waste | 10% | Covers spillage and unevenness |
| Sand type | Horticultural sand | Provides a density estimate |
| Bag size | 25 kg | Calculates purchase quantity |
Sand Selection Guidance
Horticultural or washed coarse sand usually drains well. Very fine sand can compact and restrict airflow. Confirm grading and cleanliness with your local supplier.
Builder's sand may contain unsuitable fines or salts. Play sand often holds more moisture than expected. Test questionable products before mixing large garden quantities.
Clay improvement needs careful soil testing and mixing. Small sand additions can worsen some clay textures. Blend amendments evenly throughout the treated soil profile.
Frequently Asked Questions
How much sand do I need?
Measure the bed area and target depth first. Add allowances for settlement, compaction, and handling waste. Order using the calculator's rounded purchasing quantity.
Which sand suits garden soil?
Washed coarse or horticultural sand is often preferred. Product grading still varies between local suppliers. Check cleanliness, particle size, and salt content carefully.
Can builder's sand be used?
Builder's sand may contain fines, lime, or salts. Those materials can affect drainage and soil chemistry. Seek supplier specifications before applying it to beds.
How deep should a drainage layer be?
Depth depends on bed design and drainage goals. This calculator includes a 75 millimetre preset. Confirm suitability for your plants and local soil.
How much does one cubic metre weigh?
Dry sand commonly weighs around 1,450–1,650 kilograms. Moisture and grading can change that estimate. Use the supplier's density whenever it is available.
How many bags equal one cubic metre?
The answer depends on bag weight and volume. Density also changes the weight-based bag count. Use conservative mode when both capacities are uncertain.
Should sand be compacted?
Drainage layers may settle after watering and loading. Heavy compaction can reduce useful pore space. Apply only the compaction suitable for your design.
Does wet sand weigh more?
Yes, retained water increases the transported weight. Wet sand may also occupy different bulk volume. Select moisture condition for a better weight estimate.
What waste allowance should I use?
Five to ten percent suits many projects. Irregular beds or difficult access may need more. Reduce waste through careful measuring and protected unloading.
Can sand improve clay soil?
Large, well-designed amendments may improve some clay soils. Small additions can create a concrete-like texture. Obtain local soil advice before extensive treatment.
Are bags cheaper than bulk delivery?
Small projects often favour convenient bagged products. Large projects often reduce costs through bulk supply. Compare prices using identical delivered quantities and fees.
Important Notes
Calculated density and costs remain planning estimates. Supplier moisture, packaging, and grading can differ. Verify final quantities before placing a paid order.
Plant requirements vary by species and local conditions. Excess sand can alter water and nutrient behaviour. Consult a horticultural professional for sensitive planting projects.
The calculator does not replace structural raised-bed design. Heavy material may require stronger supports and foundations. Check load limits before filling elevated garden beds.