One cubic yard is 27 cubic feet. To obtain at least that volume, buy 27 one-cubic-foot bags, 18 bags at 1.5 cu ft, or 14 bags at 2 cu ft. Fourteen 2-cu-ft bags contain 28 cu ft, not exactly one yard. Use the package’s volume, not a generic pounds-to-yards conversion.1
The formula
Volume (cu ft) = area (sq ft) × selected depth (in) / 12.
Volume (cu yd) = area × depth / 324.
Bags to buy = round up [total cu ft / package cu ft]. Texas A&M AgriLife Extension gives the cubic-yard formula and the multiply-by-27 bag conversion.1 Keep unrounded volume through the division and round only the final whole-bag count.
Bags needed for a selected cubic-yard total
Each cell shows the whole bags needed to meet or exceed the selected volume. These are our calculations using stated package volumes; package sizes vary. Do not multiply a rounded one-yard bag count for a larger order.
| Package volume | For 1 cu yd | For 3 cu yd | For 10 cu yd |
|---|---|---|---|
| 0.5 cu ft | 54 | 162 | 540 |
| 0.75 cu ft | 36 | 108 | 360 |
| 1 cu ft | 27 | 81 | 270 |
| 1.25 cu ft | 22 | 65 | 216 |
| 1.5 cu ft | 18 | 54 | 180 |
| 2 cu ft | 14 | 41 | 135 |
For example, 2-cu-ft bags require 14 for one yard, but 41 for three yards: 81 / 2 = 40.5, rounded up. Buying 14 × 3 = 42 bags introduces an extra bag. The Extension table agrees with these totals for its listed 0.75, 1, 1.25 and 2-cu-ft sizes.1
Geometric coverage from one bag
Coverage (sq ft) = package cu ft × 12 / selected depth in inches. This assumes that stated volume can be spread uniformly at that depth, before losses or a separately chosen settling allowance. The depths below are calculation inputs, not recommendations for lawns, beds or planting.
| Selected depth | 0.75-cu-ft bag | 1-cu-ft bag | 1.5-cu-ft bag | 2-cu-ft bag |
|---|---|---|---|---|
| 1 in | 9 sq ft | 12 sq ft | 18 sq ft | 24 sq ft |
| 2 in | 4.5 sq ft | 6 sq ft | 9 sq ft | 12 sq ft |
| 3 in | 3 sq ft | 4 sq ft | 6 sq ft | 8 sq ft |
| 4 in | 2.25 sq ft | 3 sq ft | 4.5 sq ft | 6 sq ft |
| 6 in | 1.5 sq ft | 2 sq ft | 3 sq ft | 4 sq ft |
| 12 in | 0.75 sq ft | 1 sq ft | 1.5 sq ft | 2 sq ft |
Three checked examples
1. A 100-sq-ft area at a selected 3 inches
Volume = 100 × 3 / 12 = 25 cu ft, or 25 / 27 = 0.925926 cu yd. That requires 25 one-cu-ft bags, 17 bags at 1.5 cu ft, or 13 bags at 2 cu ft. Thirteen 2-cu-ft bags supply 26 cu ft. This is not a full-yard order.
2. A 10 × 20-foot area at a selected 4 inches
Area = 200 sq ft. Exact volume = 200 × 4 / 12 = 66⅔ cu ft, or 2.469136 cu yd. Divide the unrounded volume by the bag size: 67 one-cu-ft bags, 45 bags at 1.5 cu ft, or 34 bags at 2 cu ft. A supplier’s bulk sales increment is a separate purchasing decision, not a reason to round the bag calculation twice.
3. A 4 × 8-foot box at a selected 12 inches
The unobstructed rectangular volume is 4 × 8 × 1 = 32 cu ft, or 1.185185 cu yd. At 1.5 cu ft per bag, 32 / 1.5 = 21⅓, so buy 22 bags, which supply 33 cu ft. At 2 cu ft per bag, buy 16 bags. This calculates volume only; it does not establish that topsoil alone is the right raised-bed growing mix.
Why a 40-lb bag does not answer the volume question
Pounds measure mass; cubic feet measure volume. A weight-only label does not provide the volume needed for this calculation. Get the stated volume or product-specific coverage from the manufacturer or supplier. Do not assume that all 40-lb topsoil bags equal one cubic foot or that a fixed number makes a yard.
For hauling, count the actual carried weight of bags and other loads and check the exact vehicle’s limits. Package volume and a generic pickup class cannot establish a safe transport quantity. See our pickup-volume and loading guide.
Net volume, settling allowance and purchase rounding
The formulas give geometric volume. If a product or project plan requires an allowance, apply it to the total volume before whole-bag rounding and label it separately. There is no automatic extra-bag rule in this chart. For a hypothetical 10% allowance on 25 cu ft, calculate 25 × 1.10 / 2 = 13.75, then round up to 14 two-cu-ft bags. Ten percent is an example, not a universal soil-settling rate.
Bagged or bulk?
Compare actual prices for the same material, usable volume and delivery/access conditions. Include fees and the supplier’s sales increment. Neither the formulas nor the package count prove that bulk is cheaper or that bagged and bulk products are interchangeable. Our bags-versus-bulk calculator compares the inputs you supply; use matching products.
FAQ
How many 2-cu-ft bags make a cubic yard?
Exactly 13.5 bags by volume. If buying sealed whole bags, 14 supply 28 cu ft, which is 1.037037 cu yd.
How many 1.5-cu-ft bags make a yard?
27 / 1.5 = 18 bags exactly, using the stated package volume.
Why does the Extension chart show one yard for 100 sq ft at 3 inches?
Its table is approximate. The exact geometric need is 25 cu ft, or 0.925926 cu yd. Its worked example rounds that to a one-yard purchase.1 A bag order calculated directly needs 13 two-cu-ft bags, while a full-yard target needs 14. Keep those targets separate.
Is the 0.0031 shortcut exact?
No. For area in square feet and depth in inches, the exact cubic-yard multiplier is 1 / 324 = 0.00308641975. The Extension page’s 0.0031 shortcut is rounded, and its accompanying sentence incorrectly describes cubic inches.1 Use the full divisor for bag-count thresholds rather than that sentence.
Does the coverage chart choose a topsoil depth?
No. Choose the depth and material from the needs of the site and planting project. The table only converts your selected depth into coverage.
Related guides
Topsoil and fill-dirt calculator | Topsoil quantity guide | Raised-bed soil guide | Mulch bag conversions
Sources
- Texas A&M AgriLife Extension, Travis County: How Much Compost, Soil or Mulch? (exact formula, bag conversion and approximate purchase charts; rounded shortcut is not used for our calculations)