Calculation details
Planning estimate only. Verify dimensions, waste, coverage, product specifications, and local requirements before purchasing materials.
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Use this result
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What does this calculator estimate?
A mulch and soil calculator converts a garden bed's dimensions into the volume of mulch or soil you need, in cubic yards and common bag sizes. Enter length, width, depth, and waste to see your order volume.
- Cubic yards = (L × W × depth) ÷ 27
- 1 cu yd = 27 cu ft
- Depth in inches ÷ 12 = feet
How mulch volume is calculated
Mulch and soil are sold by cubic yard (bulk) or by bag (1–3 cu ft). Volume is length × width × depth, converted to cubic feet and then yards. A waste factor covers settling, spillage, and uneven beds.
Limitations to watch for
The estimate assumes a flat, rectangular bed. Mulch settles after watering, so a little extra is normal. Bulk suppliers deliver in whole cubic yards — you'll need to round up to the nearest yard. Bag counts are rounded up.
How to use it in practice
Measure the bed's length and width, and pick the depth (2–3 in for mulch, more for soil). Convert to cubic yards to order bulk, or see bag counts for retail. Add waste — settling makes beds look thin after a few weeks.
['Enter the bed length and width.', 'Enter the desired depth in inches.', 'Enter waste %; the tool shows cubic yards and bag equivalents.']
How mulch and soil are measured
Volume = length × width × depth ÷ 27 for cubic yards. A 10×20-foot bed at 3 inches deep is 1.85 cubic yards. Mulch and soil are sold by the cubic yard or bag — the calculator converts to both.
Depth by use
Mulch beds want 2–3 inches; garden soil 6–12 inches in raised beds; compost amendments 1–2 inches. The depth input drives the volume more than the area.
Bags vs. bulk
Bulk yards cost less per volume but need delivery; bags (typically 2 cu ft) cost more but are portable. A cubic yard is 13.5 two-cubic-foot bags. The calculator returns the bag count for the volume.
A worked example
A 4×8-foot raised bed filled 10 inches deep: 4×8×0.83 = 26.7 cu ft ≈ 1 yard — about 14 bags of 2 cu ft. The calculator returns yards, bags, and cost.
Settling and waste
Mulch settles 10–15 percent after watering; soil compacts in beds. Ordering 10 percent extra keeps coverage even. The calculator's waste input covers it.
How this calculator works
Formula
Volume = length × width × depth (inches) ÷ 12 = cubic feet; cubic yards = cubic feet ÷ 27. Order volume = cubic yards × (1 + waste%). Bags: 1 cu ft bags = total × 27, 1.5 cu ft = total × 18, 2 cu ft = total × 13.5, 3 cu ft = total × 9.
Worked example
A 20 × 10 ft bed at 3 in deep: 200 sq ft × 0.25 ft = 50 cu ft ≈ 1.85 cu yd. With 10% waste: ≈ 2.04 cu yd, which is about 28 two-cubic-foot bags.
Assumptions to verify
- The bed is rectangular and flat.
- Depth is uniform across the bed.
- Bulk volume is rounded to practical bag counts.
Frequently asked questions
How much mulch do I need?
Multiply length × width × depth (in feet) to get cubic feet, then divide by 27 for cubic yards. A 20×10 ft bed at 3 in needs about 1.85 cu yd.
How deep should mulch be?
2–3 inches is typical for garden beds — enough to suppress weeds and retain moisture without smothering plants.
How many cubic feet are in a cubic yard?
27 (3 ft × 3 ft × 3 ft). One cubic yard of mulch covers 324 sq ft at 1 inch deep.
Should I buy bulk or bags?
Bulk is cheaper for large areas; bags are convenient for small beds and no delivery fee. The tool shows both in bag equivalents.
Why do I need extra?
Mulch settles and compacts after watering, and beds are rarely perfectly flat. 10% waste is a reasonable buffer.
How much does a cubic yard of mulch weigh?
Varies by type and moisture — bark mulch is roughly 400–800 lb per cubic yard. Check with your supplier for delivery limits.
Can I use this for soil or gravel?
Yes — the volume math is the same for any bulk material. Just use the depth appropriate for the project.
How many bags in a yard?
About 13.5 bags of 2-cubic-foot mulch.
Bulk or bags?
Bulk is cheaper per volume; bags are portable — the calculator shows both.
Cite this tool
BoringToolsKit. “Mulch and Soil Calculator.” boringtoolskit.com/mulch-soil-calculator/ (reviewed 2026-08-25). Free to reference in articles, syllabi, and answer posts with a link.
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