When to use this calculator
Leaving a central opening changes the covered area. Use measured dimensions rather than the full outer circle alone.
Explore the material quantities calculators for other questions in this topic. For a related calculation, use the Paint Cost Calculator: Estimate paint and additional supply cost after working out the paint quantity.
PUTTING IT INTO PRACTICE
Mulch Volume: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Outer bed radius (m) | 3 |
| Unmulched centre radius (m) | 1 |
| Mulch depth (cm) | 5 |
| Result | 1.256637 m³ |
- Check the input labels and enter the example values above.
- Apply the relationship: Volume = π(outer radius² − inner radius²) × depth/100.
- The result is 1.256637 m³, rounded for display.
How to interpret your result
Assumes a uniform circular ring and even depth; settling is excluded.
Calculate net geometric quantities first, then apply a project-specific allowance where appropriate. Coverage per bag or pack should come from the product label. Bulk density, trimming and compaction can substantially change order quantities.
Frequently asked questions
Does a geometric estimate include waste automatically?
Only when a waste or allowance input is provided. Otherwise add an appropriate allowance separately before ordering.
When is the mulch volume calculator useful?
Leaving a central opening changes the covered area. Use measured dimensions rather than the full outer circle alone.
How do I use the mulch volume calculator?
Enter outer bed radius (m), unmulched centre radius (m), mulch depth (cm). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Volume = π(outer radius² − inner radius²) × depth/100.
What should I check before using the result?
Assumes a uniform circular ring and even depth; settling is excluded.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
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