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Mulch Calculator
Measure the bed at its widest points and choose the finished depth to estimate bulk yards and bag count.Enter your measurements
- Cubic feet
- 27 ft³
- 2 cu ft bags
- 14 bags
Bed volume converted to cubic yards, plus 8% allowance.
How this estimate works
Bed volume converted to cubic yards, plus 8% allowance.
Measure twice and use the same unit throughout. Product coverage, material density, installation patterns, and local requirements can change the quantity you need.
Quick answer
To calculate how much mulch you need, multiply bed area by mulch depth, convert the volume to cubic yards, and add a small allowance. The calculator also converts the result to cubic feet and 2 cu ft bags.
Worked example
A 20 × 5 ft bed at 3 inches deep is 25 ft³, or 0.93 yd³. With the calculator's 8% allowance, the estimate is 1.00 yd³.
Assumptions
- The bed is represented as a rectangle.
- Depth is the final total layer depth.
- The result adds 8% for settling and measurement variation.
How deep should mulch be?
Depth depends on mulch type, soil, weeds, and what is already present. Extension guidance commonly recommends a moderate layer rather than piling material against plants; measure the current layer and follow local horticultural advice.
How many bags of mulch do I need?
One cubic yard equals 27 cubic feet. Divide the total cubic feet by the volume printed on one bag and round up. The result panel shows 2 cu ft bags automatically; for another bag size, divide the displayed cubic feet by that package size.
Where should mulch not be placed?
Keep mulch pulled back from tree trunks, plant crowns, siding, and other moisture-sensitive surfaces. The calculator estimates volume only and cannot evaluate plant health or building clearance.
How should irregular beds be measured?
Split curves into rectangles, calculate each volume, then add them. A kidney-shaped bed is usually two or three rectangles plus a leftover strip. Do not use the longest length times the widest width as if the bed were a solid rectangle unless the empty corners will also be mulched.
Last reviewed September 22, 2026. Source: University of Minnesota Extension guidance on mulching. Product instructions take priority over a general estimate.
Common questions
Short answers for the measurement details people most often need before using this calculator.
How much mulch do I need by square feet?
Multiply bed length by width for square feet, then apply the selected depth. This calculator converts that volume into cubic yards.
How many 2 cu ft bags of mulch do I need?
The detailed result converts the same bed volume into 2 cubic-foot bags and rounds up so you can buy whole bags.
How much mulch do I need for 2 inches vs 3 inches?
At 100 ft², 2 inches is about 16.7 ft³ (9 bags of 2 cu ft after the 8% allowance); 3 inches is about 25 ft³ (14 bags). Irregular beds should be split into rectangles first.