Mulch for a 10 x 20 ft bed at 3 in Bed
The exact mulch volume, bag count, and cost for a 10 x 20 ft bed at 3 in bed. Adjust any field below to try your own bed size.
Volume Needed
1.852 yd³
Bags Needed
25
Bed Area
200.0 ft²
Result
A 10 × 20 ft bed (200.0 sq ft) mulched 3" deep needs 50.0 cu ft (1.85 cu yd) of mulch, or 25 bags at 2 cu ft per bag.
Volume needed at different mulch depths (cubic yards)
What is a Mulch Calculator?
A mulch calculator converts a garden bed's footprint and a target mulch depth into the actual volume of mulch you need to buy — in cubic feet, cubic yards, or a number of bags — so you don't guess at the store or end up with pallets of leftover bags. Mulch is sold by volume, not by area, so the same bed needs roughly twice as much mulch at 4 inches deep as it does at 2 inches.
Mulch serves several practical purposes in a landscape bed: it suppresses weed growth by blocking sunlight, retains soil moisture by slowing evaporation, moderates soil temperature swings, and — for organic mulches like wood chips or bark — slowly breaks down to add organic matter back into the soil.
Mulch Needed at Different Depths
Holding the bed area at 200.0 sq ft fixed, here's how much mulch a range of common depths requires.
| Depth | Volume (cu ft) | Volume (cu yd) | Bags Needed |
|---|---|---|---|
| 1" | 16.7 | 0.62 | 9 |
| 2" | 33.3 | 1.24 | 17 |
| 3" (current) | 50.0 | 1.85 | 25 |
| 4" | 66.7 | 2.47 | 34 |
| 5" | 83.3 | 3.09 | 42 |
Mulch Volume Formula
Dividing by 12 converts the depth from inches to feet so it matches the area's units; dividing the result by 27 (there are 27 cubic feet in a cubic yard) converts to cubic yards, the unit bulk mulch is typically sold and delivered in.
How Deep Should Mulch Be?
Most landscaping guidance recommends 2 to 4 inches of mulch depth. Less than 2 inches breaks down too fast and lets weeds through; more than 4 inches can suffocate roots, hold too much moisture against tree trunks and stems (encouraging rot and pests), and actually becomes harder for water to penetrate to the soil below. Fine-textured mulches (shredded bark) can use the lower end of that range; coarse mulches (large bark nuggets, wood chips) often need the higher end to block light effectively.
Buying Bagged vs. Bulk Mulch
Bagged mulch (commonly 2 cubic feet per bag) is convenient for small beds and precise top-ups, and doesn't require a truck or trailer — but it costs more per cubic yard than bulk. Bulk mulch is sold and delivered by the cubic yard, is significantly cheaper for larger projects (often half the per-yard cost of bagged), but requires somewhere to dump a pile and a wheelbarrow to move it. As a rough rule of thumb, bulk becomes more economical once a project needs more than about 2-3 cubic yards.
Mulch Settles Over Time
Fresh mulch typically settles and compacts by 20-30% within its first year as organic material breaks down and rain packs it in, which is why many gardeners order slightly more than the bare calculated volume, or plan on a top-up application the following season rather than one enormous initial layer.
Example — Your Current Inputs
A 10 × 20 ft bed (200.0 sq ft) mulched 3" deep needs 50.0 cu ft (1.85 cu yd) of mulch, or 25 bags at 2 cu ft per bag.
Additional Example — A Front Yard Border Bed
A narrow border bed running 30 feet long by 3 feet wide (90 sq ft) gets a 2-inch layer of mulch: 90 × (2 ÷ 12) = 15 cubic feet, or 0.56 cubic yards. At 2 cubic feet per bag, that's 8 bags — small enough that bagged mulch from a garden center is more practical than ordering a bulk delivery.
About These Parameters
- Bed Shape and Dimensions
- Choose rectangle (length × width) or circle (diameter) to match your bed's footprint; for irregular beds, estimate the closest rectangle or break the bed into sections and calculate each separately.
- Mulch Depth
- How thick a layer to spread, in inches. 2-4 inches covers most landscaping needs; thinner for fine mulches on established beds, thicker for coarse mulches or new beds.
- Bag Size
- The volume printed on a bag of mulch — almost always 2 cubic feet in the U.S., though some brands sell 1 or 3 cubic foot bags.
- Price per Bag / Price per Cubic Yard
- Optional prices to estimate total cost — enter whichever matches how you plan to buy (bagged retail, or bulk delivery), or both to compare.
Frequently Asked Questions
How many bags of mulch do I need per cubic yard?
One cubic yard equals 27 cubic feet, so at the common 2-cubic-foot bag size, one cubic yard needs 13.5 bags — round up to 14 in practice, since you can't buy a partial bag.
Should mulch touch tree trunks or house siding?
No — leave a few inches of clearance around tree trunks and building foundations. Mulch piled directly against bark or siding traps moisture, which encourages rot, fungus, and pest activity ("volcano mulching" around trees is a well-known landscaping mistake to avoid).
How often does mulch need to be replaced?
Organic mulch typically needs topping up every 1-2 years as it decomposes and settles; inorganic mulches (rubber, rock) last much longer but don't add organic matter to the soil the way wood or bark mulch does.
Is bulk mulch cheaper than bagged mulch?
Usually, yes, per cubic yard — bulk delivery cuts out packaging and per-bag retail markup. It only pays off once you need enough volume to justify a delivery minimum (typically a few cubic yards), so small beds are often still cheaper and easier with bagged mulch from a garden center.