Mulch Calculator

How to Use the Mulch Calculator

Add a region for each simple shape. Choose rectangle or circle, enter the dimensions and the depth, then calculate. Use Add area for another bed. Reset restores a single 10 ft × 4 ft rectangle at 3 inches with no allowance and no package. The form works as a normal page submission. When JavaScript is available, adding or removing a region stays on the page and the server still performs the calculation.

Measuring Garden Beds

For a rectangle, measure the long side and the short side. For a circle, measure the diameter — the full distance across the bed, not the radius. Use one unit per field (inches, feet, yards, centimeters, or meters). The calculator converts each field to meters before multiplying. A bed that bends around a walk should be split into more than one region. The tool does not trace an irregular outline by itself.

How to Calculate Mulch Volume

1. Rectangle area = length × width. Circle area = π × (diameter ÷ 2)².
2. Region volume = area × depth.
3. Base volume = the sum of the regions.
4. Order volume = base volume × (1 + allowance ÷ 100).

Results are shown in cubic feet, cubic yards, and cubic meters. One cubic yard is 27 cubic feet.

How Deep Should Mulch Be?

Depth is an input. This calculator does not apply a required depth. University of Illinois Extension’s Proper Mulching Techniques sheet (reviewed 2026-10-14) describes a 2 to 4 inch layer on well-drained sites, with composted material closer to 2–3 inches and coarse mulch closer to 3–4 inches. Virginia Cooperative Extension publication SPES-661 (reviewed 2026-10-14) discusses finer particles in a thinner layer than coarser particles, with a settled depth often discussed around 2 to 4 inches, and keeping mulch clear of trunks. Those are planning references, not a single depth for every plant, soil, or product. Keep mulch off trunks and stems.

Cubic Feet vs Cubic Yards

Bagged mulch is often labeled in cubic feet. Bulk yards are sold by the cubic yard. A 10 cubic foot bed is 10 ÷ 27 = 0.3704 cubic yards. Ordering “10 yards” when you need 10 cubic feet overstates the job by a factor of 27.

Calculating Bags of Mulch

Choose a package volume of 1, 1.5, 2, or 3 cubic feet, or type a custom volume in cubic feet or liters. Those presets are volume labels. They do not mean a store stocks that size. Bags required is the smallest whole number of packages whose volume meets the order. Purchased volume is bags × package volume. Surplus is purchased volume minus order volume. Leave packaging on “bulk volume only” when you are not counting bags.

Bulk Mulch vs Bagged Mulch

Bags are easy to carry and leave a known leftover count. Bulk loads suit larger volumes and are usually ordered in cubic yards. Compare the order volume in yards with the supplier’s minimum load. This page does not look up delivery minimums or product names.

Material Cost Estimation

Enter your own price in USD per bag, per cubic yard, or per cubic meter. Per-bag cost multiplies that price by the whole bags. Bulk cost multiplies it by the order volume, including allowance, not by the surplus you might not buy in bulk. Delivery, tax, and labor are excluded. An empty price leaves the cost blank.

Worked Examples

Each example below lists the inputs and the results, so you can check the math by hand or rerun it in the calculator above.

10 ft × 4 ft × 3 in, no allowance

• Area: 40 ft².
• Base and order volume: 10 ft³, 0.3704 yd³, 0.2832 m³.
• With a 2 ft³ package: 5 bags, purchased volume 10 ft³, surplus 0 ft³.

Same bed, 10% allowance, bulk price

Order volume becomes 11 ft³ (0.4074 yd³). A 2 ft³ package needs 6 bags (purchased 12 ft³, surplus 1 ft³). A user-entered price of $45 per cubic yard — an illustration, not a market quote — is 0.4074 × 45 = $18.33.

8 ft diameter circle, 3 in deep

Area 50.2655 ft². Volume 12.5664 ft³ (0.4654 yd³, 0.3558 m³).

Exact bag boundary

10 ft³ of order and a 2 ft³ package stay at 5 bags. The count does not become 6 when the order lands on a whole number of packages.

Common Mistakes and Limitations

• Using the radius where the form asks for diameter.
• Treating a bag’s weight as its cubic feet.
• Forgetting to split a curved bed into rectangles and circles.
• Assuming 2–4 inches, or any allowance, is mandatory.
• Comparing a per-bag total with a bulk total that ignores delivery minimums.

For a planning discussion of depth, measuring, and bulk versus bags, see How Much Mulch Do I Need for My Garden?