This calculator estimates how much bark, wood chip, or similar mulch is needed to cover a garden bed at a chosen depth. Use it for a new bed, a seasonal top-up, or to compare bagged material with bulk delivery before visiting the garden centre. It does not assess plant needs, remove the volume of existing mulch, or include landscape fabric, edging, delivery, and spreading labour. US mode shows cubic feet, cubic yards, and typical 2 ft³ bags; UK mode uses cubic metres and litres where appropriate, with depth entered in centimetres. Bag sizes and bulk coverage vary, so check the label or send the result to your supplier to confirm how many bags or loose cubic metres they recommend.
How this is calculated
Mulch is spread much thinner than concrete or gravel — typically 2 to 4 inches — so small depth errors change the total by a large percentage. This calculator keeps depth as its own clearly labeled field rather than folding it into a single 'thickness' guess.
Because mulch is most often bought in bags of a fixed volume, the result also converts the total cubic yardage into a bag count using a standard 2 cubic foot bag, so you know how many bags to actually put in the cart.
For an existing bed, measure the depth already in place and enter only the top-up needed. Adding a fresh 3 inches every year without checking the old layer can leave roots and stems buried too deeply.
Bulk mulch settles and can be heaped differently by each yard, while bagged coverage depends on the printed bag volume. Confirm the actual bag size or loader-bucket measure before paying.
Enter your dimensions below. Results update as you type. Costs are planning ranges — confirm with a local supplier before you order.
Bed dimensions
ft
ft
in
Typical: 2–3 in
Add cost details
$
Results
Mulch volume
0.44 yd³
Bags needed
6 bags
2 ft³ bags
Estimated cost
$27
Frequently asked questions
How deep should mulch be?
2 to 3 inches (5–7.5 cm) is the standard depth for most garden beds. Go thicker than 4 inches (10 cm) and it can start to suffocate roots or hold too much moisture against stems.
Is it cheaper to buy mulch in bags or bulk?
Bulk (delivered by the cubic yard) is almost always cheaper once you need more than about 3 cubic yards — bagged mulch carries a per-bag packaging and handling cost that adds up fast at that volume.
Do I need to remove old mulch before adding new mulch?
Not usually — a thin layer of old, broken-down mulch can stay as long as the combined depth doesn't exceed 3–4 inches. Rake it out first if it's matted or more than an inch thick.
Does this calculator account for mulch settling over time?
No — it calculates the volume needed to reach your target depth at the time of spreading. Organic mulch typically compresses 10–20% over its first season, which is worth keeping in mind if you're topping up rather than starting fresh.
Last updated 2026-06-15. Formulas are planning methods — confirm with a supplier before you order. See how we calculate and the disclaimer.