How the calculation works
- Bed area = length × width.
- Cubic yards = area × depth in inches ÷ 324. One cubic yard covers 324 sq ft one inch deep, as Mississippi State University Extension explains (27 cu ft × 12 = 324).
- Bags = cubic yards × 27 ÷ bag size in cubic feet, rounded up.
Example
Bed length: 20 ft · Bed width: 10 ft · Depth: 3 in · Bag size: 2 cu ft
Result: 1.85 cu yd or 25 bags.
Tips before you buy
- Mulch settles, so measure depth after raking it level.
- Bulk delivery by the yard is usually cheaper than bags for large beds.
- The same formula works for topsoil and compost.
- Always confirm coverage and yield with the manufacturer's label — products differ.
FAQ
What depth should I enter?
Enter the finished depth you want after spreading. For the right depth for your plants, check your local extension service.