Mulch Calculator
Calculate how many cubic yards and bags of mulch you need to cover any garden bed or landscape area. Works for rectangle, circle, and triangle shapes.
Covering a gravel path or driveway? Try the Gravel Calculator →
This mulch calculator takes the guesswork out of any landscaping project. Whether you're refreshing garden beds, mulching around trees, or covering a new planting area, enter your shape, dimensions, and desired depth to instantly get the volume in cubic feet, cubic yards, and the exact number of bags you need. The calculator handles rectangle, circle, and triangle shapes and supports common bag sizes of 1.5, 2, and 3 cubic feet. Most landscapers recommend buying a small amount of extra mulch to account for settling and uneven application — rounding up to the nearest full bag is good practice.
How to Use the Mulch Calculator
- Select the shape of your garden bed — rectangle, circle, or triangle.
- Enter the dimensions in feet: length and width for rectangles, diameter for circles, base and height for triangles.
- Enter the desired mulch depth in inches (2 to 3 inches is recommended for most beds).
- Select the bag size you plan to purchase: 1.5, 2, or 3 cubic feet.
- Click "Calculate Mulch" to see your cubic feet, cubic yards, and total bag count.
Mulch Coverage Example
A standard rectangular garden bed measuring 10 feet by 20 feet, mulched to 3 inches deep:
| Measurement | Value |
|---|---|
| Area | 200 sq ft |
| Volume | 50.00 cubic feet |
| Cubic yards | 1.85 cu yd |
| Bags needed (2 cu ft) | 25 bags |
At this volume, purchasing bulk mulch by the cubic yard from a landscape supplier is often more economical than buying 25 individual bags. Bags are most convenient for small beds, spot touch-ups, or areas with difficult truck access.
Frequently Asked Questions
How deep should mulch be?
For most garden beds, 2 to 3 inches of mulch is ideal. At that depth mulch retains moisture, suppresses weeds, and regulates soil temperature effectively. Do not exceed 4 inches — piling mulch too thick can suffocate plant roots and create conditions for fungal disease. For newly planted beds or areas with erosion concerns, 3 inches is the better choice.
How many bags of mulch equal a cubic yard?
There are 27 cubic feet in a cubic yard. A 2 cubic foot bag requires 13.5 bags to equal one cubic yard. A 1.5 cubic foot bag requires 18 bags. A 3 cubic foot bag requires 9 bags. When covering larger areas — anything over 100 square feet — buying bulk mulch by the cubic yard from a landscape supplier is typically 30 to 50 percent cheaper than purchasing individual bags.
How much does a yard of mulch cover?
At 3 inches deep, one cubic yard of mulch covers approximately 108 square feet. At 2 inches deep it covers about 162 square feet. At 4 inches deep it covers roughly 81 square feet. For reference, one cubic yard covers a 10-foot by 10-foot bed at about 3.25 inches deep — close to the standard recommended depth for most ornamental plantings.
Should I remove old mulch before adding new mulch?
Usually not. If the old mulch layer is already near 3 inches deep, rake and loosen it first, then top-dress with just 1 to 2 inches of new mulch to refresh coverage without over-mulching. Only remove old mulch entirely if it has become compacted and is blocking water infiltration, or if disease or fungal problems such as artillery fungus are present in the existing layer.
What type of mulch lasts the longest?
Hardwood bark mulch typically lasts 1 to 2 years before breaking down. Cedar and cypress mulches resist decomposition longer and also naturally repel insects, making them popular for ornamental beds. Dyed wood mulch holds color well visually but decomposes faster than natural bark. Rubber mulch lasts the longest of all options but provides no soil-enriching benefit since it does not break down into organic matter.