Is bulk mulch cheaper than bagged?

Usually yes, per cubic yard, once you need more than about 2-3 cubic yards.

How deep should mulch be?

2-3 inches is commonly recommended — deep enough to suppress weeds, shallow enough to avoid suffocating roots.

Does this work for soil the same way as mulch?

Yes — the volume math is identical; only the typical application depth differs.

Does this account for soil settling over time?

No — organic mulch and loose soil both settle and decompose and may need topping up.

Can I mix mulch types in this calculator?

The volume math is the same regardless of mulch material — only the weight per bag differs.

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Math & Everyday

Mulch/Soil Calculator

Cubic yards and bags of mulch or soil needed for a garden bed.

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About the Mulch/Soil Calculator

Calculates cubic yards and standard 2 cu ft bags of mulch or garden soil needed for a bed, from its area and desired depth.

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How to use it

Choose mulch or garden soil / topsoil.
Enter the bed's length and width.
Enter the desired depth.
Read the volume needed in cubic yards and the equivalent bag count.

Formula

Volume (cubic ft) = bed area × depth (inches ÷ 12). Cubic yards = volume ÷ 27. Bags needed = ceiling(volume ÷ 2), since 2 cu ft is the standard US retail bag size.

Worked example

A 10ft × 5ft bed at 3 inches of mulch depth: 12.5 cubic ft (0.46 cubic yards), requiring 7 bags at 2 cu ft each.

Interpreting your result

2 cubic feet is the Mulch and Soil Council's standard retail bag size in the US — about 13.5 bags per cubic yard. For areas beyond roughly 2-3 cubic yards, bulk delivery is usually more cost-effective. Recommended mulch depth is typically 2-3 inches; deeper can suffocate plant roots.

Recommendations

• 2-3 inches is the sweet spot for mulch depth — thicker layers can suffocate roots or trap excess moisture.
• For large beds, compare bulk delivery pricing against bag pricing — bulk is almost always cheaper past a few cubic yards.
• Refresh mulch annually or as it decomposes/compacts.

Frequently asked questions

It's the Mulch and Soil Council's standard US retail bag size.