One cubic yard of mulch equals 13.5 bags of 2 cu ft mulch (buy 14), 9 bags of 3 cu ft, or 18 bags of 1.5 cu ft. A 20×8 ft bed at 3 inches deep needs about 1.56 cubic yards — 21 bags of 2 cu ft with 5% extra. Run your own bed in the free QtyLab mulch calculator.
Just need bags per cubic yard? See how many bags of mulch in a yard — 1.5, 2 and 3 cu ft bags, coverage by depth, and counts for common bed sizes.
Bags per cubic yard
| Bag size | Bags per cubic yard |
|---|---|
| 1.5 cu ft | 18 |
| 2 cu ft (most common) | 13.5 |
| 3 cu ft | 9 |
Coverage chart by depth
| Depth | Sq ft per cubic yard | Sq ft per 2 cu ft bag |
|---|---|---|
| 2 in | 162 | 12 |
| 3 in | 108 | 8 |
| 4 in | 81 | 6 |
Bed chart: bags for common sizes
3 inches deep, 5% extra, 2 cu ft bags rounded up. Click a size to open it in the calculator.
| Bed | Cubic yards | 2 cu ft bags |
|---|---|---|
| 10 × 3 ft (foundation strip) | 0.29 | 4 |
| 20 × 4 ft | 0.78 | 11 |
| 10 × 10 ft | 0.97 | 14 |
| 30 × 5 ft | 1.46 | 20 |
| 20 × 8 ft | 1.56 | 21 |
Past about 2 cubic yards, bulk mulch from a landscape yard is usually cheaper than bags — ask about delivery minimums.
Mulch can make a garden bed look finished, help hold moisture, and give weeds less room to grow. The tricky part is buying the right amount. Order too little and you are back at the store; order too much and you have leftover piles taking up space. The good news is that mulch quantity is easy to estimate once you know two things: the area you want to cover and the depth you want to install. This guide walks through the math, explains cubic yards and bags, and points you to the free QtyLab mulch calculator when you want a quick answer.The quick rule of thumb: plan on 2 to 3 inches
For most landscape beds, a mulch layer of 2 to 3 inches is a practical starting point. About 2 inches works well for refreshing an existing bed or covering a lightly used area. Around 3 inches gives more coverage and is common for a new bed, though piling mulch too deeply can create problems around plants and tree trunks. Keep mulch pulled a few inches away from stems and trunks. A neat ring of bare space helps avoid constant moisture against the bark and makes the finished job easier to maintain.How to calculate mulch in cubic yards
Bulk mulch is usually sold by the cubic yard. Use this simple formula: Length (feet) × width (feet) × depth (inches) / 324 = cubic yards of mulch The number 324 converts square feet and inches into cubic yards. If your bed is irregular, split it into rectangles, squares, or triangles, calculate each section, and add the results together.Example: a rectangular garden bed
Suppose a bed is 20 feet long and 6 feet wide, and you want a 3-inch layer:- 20 × 6 = 120 square feet
- 120 × 3 = 360
- 360 ÷ 324 = 1.11 cubic yards
What if my bed is circular or irregular?
For a circular bed, measure the diameter from edge to edge and use the calculator rather than trying to guess. A circle’s area is based on its radius, so a few inches can change the estimate more than expected. For an L-shaped or curved bed, divide it into simple sections. Measure each rectangle separately, then add the areas. For a triangle, multiply the base by the height and divide by two. Once you have total square footage, apply your planned depth. If you have several beds, enter each one in the mulch calculator or total their square footage first. Measuring each section is usually more accurate than estimating the whole yard by eye.How many bags of mulch do I need?
Bagged mulch is commonly sold in 2-cubic-foot bags, although bag sizes vary by product and retailer. To convert cubic yards to 2-cubic-foot bags: Cubic yards × 13.5 = approximately 2-cubic-foot bags For example, 1.11 cubic yards × 13.5 equals about 15 bags. Check the label before buying because a 1.5-cubic-foot bag and a 3-cubic-foot bag will cover different areas. The QtyLab mulch calculator can help you compare volume and bag counts without doing the conversion by hand. Once you know the volume, shop bagged mulch if it fits your project, access, and budget. Bags are convenient for small beds and backyards where a bulk delivery is not practical. For larger areas, bulk mulch often means fewer individual packages and less handling.How much extra mulch should I buy?
For a straightforward, level bed with accurate measurements, adding roughly 5% to 10% is usually enough. Consider a little more if the ground is uneven, the bed has many edges, or you are working around established plants. Mulch can settle after installation, but buying a large surplus is not always helpful: color and texture can vary between batches, and old mulch is not always easy to store. If you are topping up an existing bed, measure the current depth first. You may need less than a full 2- or 3-inch layer. Lightly rake old mulch into place, remove obvious debris, and add enough new material to reach your target depth.Common mulch-measuring mistakes
- Using inches as feet: Depth belongs in inches in the formula above. Do not enter 3 feet when you mean 3 inches.
- Forgetting sections: Add every bed, strip, and island that needs coverage.
- Over-mulching: More is not automatically better. Keep the layer near the planned depth and avoid volcano-shaped piles around trees.
- Ignoring access: Confirm where a bulk delivery can be dropped, or make sure bagged mulch can be moved from the vehicle to the bed.
- Skipping the label: Bag volume and recommended coverage differ, so use the stated cubic-foot size.
Use the free mulch calculator
Want the answer for your own project? Open the free QtyLab mulch calculator, enter your measurements and desired depth, and use the result to plan a bulk order or estimate the number of bags. It is a practical way to check your math before you spend money. Planning another outdoor project? QtyLab also has a gravel calculator for paths, driveways, and drainage, a sod calculator for lawn areas, and a fertilizer calculator for application estimates. Visit the QtyLab home page to find more free quantity-planning tools. Planning note: These estimates are for planning and purchasing guidance only. Actual coverage varies with material type, settling, ground conditions, product size, and installation technique. Confirm product specifications and site requirements before ordering or installing.Shopping list for a 20×8 bed (3 in)
- 21 bags of 2 cu ft mulch (or about 1.6 cubic yards bulk) — shop bagged mulch
- 1 bow rake or landscape rake to spread it — shop rakes
- 1 wheelbarrow if you’re buying bulk — shop wheelbarrows
- About 56 ft of landscape edging (bed perimeter), optional — shop landscape edging
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Doing a path instead? Use the gravel calculator and see how much gravel you need.
FAQ
How many bags of mulch are in a yard?
A cubic yard is 27 cubic feet, so it equals 13.5 bags of 2 cu ft mulch, 9 bags of 3 cu ft, or 18 bags of 1.5 cu ft. Round up when you buy.
How much area does a yard of mulch cover?
About 162 sq ft at 2 inches deep, 108 sq ft at 3 inches, and 81 sq ft at 4 inches.
How many bags of mulch for 100 square feet?
At 3 inches deep, 100 sq ft needs 25 cubic feet, or 13 bags of 2 cu ft (12.5 rounded up). At 2 inches, 9 bags.
How deep should mulch be?
Most beds use 2 to 3 inches. Topping up an existing bed often only needs 1 to 2 inches. Keep mulch pulled back from tree trunks and plant stems.
Is bagged or bulk mulch cheaper?
Bags are convenient for small beds. Past about 2 cubic yards, bulk from a landscape yard is usually cheaper per yard, though delivery fees and minimums apply.
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