How this calculator works
The volume is bed area times the depth of the new layer. Existing mulch should be measured first so the final combined layer is appropriate for the material and plants. A 5 cm default is an example, not a universal depth recommendation. Keep mulch away from stems and trunks. Weight uses the supplied bulk density; bags are rounded up before costing.
Formula
Volume = area × depth. Mass = volume × bulk density. Depth = volume/area. Area = volume/depth. Bags = ceiling(volume/bag volume). Cost uses the selected CAD per m3, kg or bag basis.
Worked example
A 20 m2 bed with a 5 cm layer needs 1 m3. With 60 L bags this requires 17 bags. At $5 per bag the purchase costs $85 and supplies 1.02 m3.
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Frequently asked questions
Why are bag and bulk costs different?
Bag counts round upward to complete packages. Bulk pricing here uses the exact calculated volume.
How do I measure a ring around a tree?
Select circular ring and enter outer and inner radii. The inner circle is excluded from coverage.
Should I add this depth over existing mulch?
Enter only the extra thickness required to reach your planned total depth. Excessive mulch can interfere with water and air movement.