Saved Calculation History
Formula Used
Rectangular volume equals length times width times depth. Circular volume equals π times radius squared times depth. Multiple beds multiply the single-bed result by their count.
Net volume equals gross volume minus deductions. Purchase volume adds the selected settling allowance. Component volume equals purchase volume times each component percentage.
Bag count always rounds up to the next whole bag. Bulk orders round upward by the chosen supplier increment. Weight uses volume multiplied by selected soil density.
How to Use
Add every raised bed and choose its shape. Enter dimensions with the correct length units. Use the count field for identical beds.
Add deductions for logs, gravel, or existing fill. Choose a settling allowance for future compaction. Select or customise the soil mix.
Enter bag and bulk prices before calculating. Review purchasing comparisons and handling weight. Export or save the final project summary.
Suggested Soil Depths
| Planting use | Suggested depth | Common examples |
|---|---|---|
| Shallow planting | 6 inches | Radishes, salad greens, herbs |
| Leafy vegetables | 8 inches | Lettuce, spinach, chard |
| General vegetables | 12 inches | Beans, peppers, brassicas |
| Deep-rooted plants | 18 inches | Tomatoes, aubergines, perennials |
| Root crops | 24 inches | Carrots, parsnips, potatoes |
Example Calculation
A bed measures 8 feet by 4 feet. Its soil depth is 1 foot. The gross volume is 32 cubic feet.
A ten percent settling allowance increases demand. The purchase volume becomes 35.2 cubic feet. Forty-litre bags would require twenty-five whole bags.
Actual bag counts depend on supplier labelling. Always check filled bag volume. Order slightly more when dimensions are uncertain.
Example Data Table
| Bed size | Depth | Gross volume | With 10% allowance |
|---|---|---|---|
| 4 ft × 4 ft | 1 ft | 16 ft³ | 17.6 ft³ |
| 6 ft × 3 ft | 1 ft | 18 ft³ | 19.8 ft³ |
| 8 ft × 4 ft | 1 ft | 32 ft³ | 35.2 ft³ |
| 2 m × 1 m | 0.3 m | 0.6 m³ | 0.66 m³ |
Bagged Soil or Bulk Soil
Bagged soil suits small beds and restricted access. It is easy to move and measure. Packaging can increase the total project cost.
Bulk soil usually suits larger projects. Delivery can reduce repeated handling. Minimum orders may create useful leftover soil.
Compare both totals before ordering. Include delivery, labour, tax, and discounts. Check supplier volume and moisture specifications carefully.
Frequently Asked Questions
How much extra soil should I order?
Ten percent is a practical starting allowance. Loose mixes settle after watering. Deep organic mixes may settle more.
Why does the calculator round bags upward?
Suppliers sell complete bags only. Partial calculations cannot be purchased directly. Rounding avoids an unfinished bed.
Can I calculate several bed shapes together?
Yes, add each bed separately. Choose its correct shape and dimensions. The calculator combines every result.
How are L-shaped beds calculated?
The cut-out rectangle is removed from the outer rectangle. The remaining area is multiplied by depth. Counts then multiply that volume.
What is Mel's Mix?
It commonly uses equal parts compost, peat, and vermiculite. Local substitutes can change performance. Check plant and climate needs.
Does wet soil weigh more?
Yes, retained water adds substantial weight. Saturated material can be difficult to move. Use weight results as estimates.
Should gravel be placed below raised bed soil?
Gravel is not always required. Drainage depends on soil and site conditions. Deduct its volume when used.
Can I use litres and feet together?
Yes, each dimension includes a unit selector. The calculator converts inputs internally. Results show several common volume units.
What does normalise to 100% do?
It scales all entered mix percentages proportionally. Their relative balance stays similar. The final total becomes exactly 100%.
How accurate are component costs?
Accuracy depends on entered supplier prices. Component pricing assumes consistent volume rates. Delivery and handling can vary.
Can saved calculations be reopened?
Saved summaries remain in local browser storage. They can be reviewed later. Form inputs are not fully restored.