Mulch Calculator

Calculate mulch volume in cubic yards and cubic feet for a rectangular bed using feet and inches.

Calculated Result

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How to Use the Mulch Calculator

Measure the bed’s length and width in feet. Enter the intended mulch depth in inches, then calculate. For an irregular garden, divide it into rectangles, calculate each area’s volume at the required depth, and add the results before ordering.

Formula and Explanation

Cubic yards = Length × Width × Depth ÷ 324

Length × width gives square feet. Dividing the depth in inches by 12 converts it to feet, so the product is cubic feet. Dividing again by 27 converts cubic feet to cubic yards. Combining the two divisors gives the formula’s factor of 324.

The result assumes a flat rectangular footprint and an even depth. It does not automatically add material for settling, uneven ground or delivery increments. Choose a suitable depth for your plants and keep mulch away from stems and trunks.

Worked Example

A bed 20 feet long and 10 feet wide at 3 inches deep needs 20 × 10 × (3 ÷ 12) = 50 cubic feet. That is 50 ÷ 27 = 1.8519 cubic yards. If bags contain 2 cubic feet each, the measured volume corresponds to 25 bags.

Frequently Asked Questions

What units should I enter?

Enter length and width in feet and depth in inches. The result is shown in cubic yards, with cubic feet underneath. Do not enter inches in the length or width fields.

How do I calculate an irregular bed?

Split its footprint into smaller rectangles that approximate the shape, calculate each section and add their volumes. Avoid overlapping the sections when measuring.

How many bags of mulch do I need?

Divide the cubic-foot result by the volume printed on each bag. Round up if the calculation requires part of a bag; bag sizes vary, so check the label.

Does the volume include an allowance for settling?

No. It is the geometric volume at your entered depth. Any allowance for settling or uneven ground must be chosen separately.