Mulch Calculator
Enter the bed size and the mulch depth to get the cubic yards for a bulk delivery and the number of bags, with an allowance for settling. Set the bag size from the label.
Quick answer: A 10 ft × 10 ft bed mulched 3 in deep is 25 cubic feet, or 0.93 cubic yards; with a 5% allowance that is 14 bags of 2 cu ft or 9 bags of 3 cu ft.
Mulch volume is area × depth. Multiply length by width in feet, multiply by the depth in feet (inches ÷ 12), then divide by 27 for cubic yards. Divide cubic feet by the bag size and round up for bags.
Example: a 10 ft × 10 ft bed at 3 in deep is 25 ft³, or 0.93 yd³. With a 5% allowance that is 26.25 ft³: 14 bags of 2 ft³, or 9 bags of 3 ft³.
Method
How this calculator works
The volume formula matches the Texas A&M AgriLife Extension method, and the 3 inch default follows University of Florida guidance. Allowance and bag size are yours to set.
Cubic yards of mulch
Area times depth in feet, divided by 27. The extension service writes it as length × width × (depth in inches ÷ 12) ÷ 27, and rounds the answer up to a whole or half yard when ordering.
Cubic yards = L (ft) × W (ft) × (Depth (in) ÷ 12) ÷ 27Depth and coverage
UF/IFAS recommends mulching to a depth of about 3 inches, and says one cubic yard covers 324 ft² at 1 inch deep, or 108 ft² at 3 inches. The calculator starts at 3 in and warns above 4 in.
Coverage of 1 yd³ (ft²) = 324 ÷ Depth (in)Allowance
Mulch settles, and beds are never perfectly even. The calculator starts at 5% and lets you pick 0 to 25%. That is a common rule of thumb, not a standard. Bulk volume is also rounded up to the next half yard, a common way to order bulk material.
Order volume = Net volume × (1 + Allowance ÷ 100)Bags
Bag size is printed on the bag: 2 cubic feet is common, 3 cubic feet is also sold, and some bags are labeled in liters (1 ft³ = 28.316846592 L). Bags always round up. Coverage per bag shows how far one bag goes at your depth.
Bags = round up (Volume with allowance (ft³) ÷ Bag size (ft³))One bag covers (ft²) = Bag size (ft³) × 12 ÷ Depth (in)Worked example: a 10 ft × 10 ft bed, 3 in deep, 5% allowance
Arithmetic checked| Step | Math | Result |
|---|---|---|
| Area of the bed | 10 × 10 | 100 ft² |
| Volume at 3 in | 100 × (3 ÷ 12) | 25 ft³ |
| Convert to cubic yards | 25 ÷ 27 | 0.9259 yd³ |
| Add a 5% allowance | 25 × 1.05 = 26.25 ft³; 26.25 ÷ 27 | 0.9722 yd³ |
| Bulk order, rounded up to the next 0.5 yd³ | 0.9722 → 1.0 | 1 yd³ |
| Bags of 2 ft³ | 26.25 ÷ 2 = 13.125, round up | 14 bags |
| Bags of 3 ft³ | 26.25 ÷ 3 = 8.75, round up | 9 bags |
| One 2 ft³ bag covers | 2 × 12 ÷ 3 | 8 ft² |
| You would order | 1 yd³ in bulk, or 14 bags (2 ft³) | |
Disclaimer
Results are planning estimates based on the dimensions and assumptions you enter. They are not engineering, structural or building-code advice. Product yields, densities and coverage vary by manufacturer, batch and site conditions. Check product labels, your supplier and your local building department before you order materials or start work. Read the full calculation disclaimer.
Accuracy
What affects your estimate
Bed size and depth do most of the work. These details decide whether the number matches what lands on the driveway.
Depth
Three inches is the usual advice from UF/IFAS. Going deeper uses a lot more mulch, and deep mulch can harm plants. Enter the depth of the new mulch you will add, not the total with what is already there.
Bag size and brand
Bags are not all the same size, and some are marked in liters. Check the label and type the size in the bag-size field before you trust the bag count.
Bulk or bags
One cubic yard is 27 ÷ 2 = 13.5 bags of 2 ft³, so 14 bags, or 9 bags of 3 ft³. Compare the price of 14 bags with a bulk yard, plus delivery, at your own suppliers.
Irregular beds
The calculator takes a rectangle or a circle. For a curved bed, find its area with the square footage calculator, then enter that area as the length and 1 ft as the width.
Keep mulch a few inches away from tree trunks and house siding. This is an estimate of quantity; bag sizes and coverage are printed on the bag, so check yours before you buy.
Common mistakes
Piling mulch too deep
More than about 3 in does not help the plants and can hurt them. If the number looks huge, check the depth before you order.
Assuming every bag is 2 cubic feet
Bags come in different sizes. A 3 ft³ bag needs one third fewer bags than a 2 ft³ bag for the same bed.
Rounding the bag count down
Running out with a few feet left to cover means a second trip. Bags always round up here, after the allowance.
Questions people ask
How much mulch do I need?
Multiply the bed length by the width in feet and by the depth in feet (3 in = 0.25 ft), then divide by 27 for cubic yards. A 10 ft × 10 ft bed at 3 in is 0.93 yd³. For other shapes, see how to calculate cubic yards.
How many 2 cu ft bags of mulch are in a cubic yard?
27 ÷ 2 = 13.5, so you need 14 bags. With 3 ft³ bags it is 27 ÷ 3 = 9. The guide on bags of mulch has the full table.
How many square feet does a yard of mulch cover?
UF/IFAS gives 324 ft² at 1 in deep, which is 108 ft² at 3 in deep.
How deep should mulch be?
University of Florida extension recommends about 3 inches. Keep it a few inches away from tree trunks and siding.
How much mulch do I need for 200 square feet at 2 inches?
200 × (2 ÷ 12) = 33.33 ft³, or 1.23 yd³. With a 5% allowance that is 35 ft³, which is 18 bags of 2 ft³.
Related calculators and guides
Sources
Where the numbers come from
- Texas A&M AgriLife Extension (Travis County) how much compost, soil or mulch (volume formula), accessed October 16, 2026.
- UF/IFAS Gardening Solutions mulch depth and coverage, accessed October 16, 2026.
- NIST Handbook 44, Appendix C (cubic yard and liter conversions), accessed October 16, 2026.