Mulch, gravel and soil calculator
Enter the bed's length, width and the depth you want, pick the material, and see the cubic yards, the number of bags, the weight and the cost either way.
Cubic yards needed
0.741
20.000 cubic feet, or 10 bags
How to use it
- Measure the bed's length and width in feet. For an odd shape, break it into rectangles and add the beds up with the count field, or use the average width.
- Choose the depth. Mulch is usually laid 2 to 3 inches deep; a gravel path 3 to 4; a new raised bed 8 to 12 inches of soil.
- Pick the material so the bag size and weight are right.
- Enter the bag price and the bulk price per yard if you have them, and read whether bags or a delivery comes out cheaper.
Worked example
A bed 20 ft by 4 ft, mulched 3 in deep.
Area 80 sq ft. Volume: 80 × 3 ÷ 12 = 20 cubic feet, which is 0.741 cubic yards. In 2 cu ft bags that’s 10 bags, weighing about a quarter of a ton.
At $4.50 a bag the mulch costs $45.00. A bulk supplier at $45 a yard would charge for a full yard, also $45.00, and deliver a third more than you need. For this size, bags win on convenience; for three beds like it, bulk wins clearly.
How this is calculated
Volume is area times depth: length times width in feet gives square feet, and multiplying by the depth in inches divided by twelve gives cubic feet. A cubic yard is 27 cubic feet, and bulk material is sold by the yard, rounded up to whole yards by most suppliers. Bags are counted by dividing the cubic feet by the bag size and rounding up, using the common sizes: two cubic feet for mulch, three-quarters for topsoil, one for compost, half for gravel and sand. The weight line uses typical densities, from about 25 pounds a cubic foot for dry mulch to 100 for gravel, and is there to tell you whether a pickup can carry it. If you enter both prices, the calculator says which way is cheaper for this job.
area = length × width × number of beds
cubic feet = area × depth in inches ÷ 12
cubic yards = cubic feet ÷ 27
bags = cubic feet ÷ bag size, rounded up
weight in tons = cubic feet × pounds per cubic foot ÷ 2,000, using typical densities: mulch 25, compost 40, topsoil 75, sand 95, gravel 100
Rates, sources and limits
Last reviewed 23 Sep 2026 by the CalcRabbit team. Estimates only, not financial, tax or medical advice.
Frequently asked questions
How deep should mulch be?
Two to three inches for most beds: enough to suppress weeds and hold moisture without smothering roots. Keep it an inch or two away from stems and trunks. When topping up an existing layer, measure what's there and only add the difference.
How many bags are in a cubic yard?
A cubic yard is 27 cubic feet, so 13.5 two-cubic-foot bags of mulch, 36 three-quarter-cubic-foot bags of topsoil, or 54 half-cubic-foot bags of gravel. That comparison alone explains why bulk delivery wins for anything above a couple of yards.
Will it fit in my truck?
A half-ton pickup is rated for roughly 1,000 to 1,500 pounds in the bed. That's about a yard of mulch, but only a third of a yard of gravel, which weighs around 2,700 pounds a yard. Check the weight line before you drive to the yard.
Why did my supplier's number differ?
Suppliers round up to whole or half yards, and some quote by the ton for stone. Mulch also settles: a fresh 3-inch layer becomes 2 inches within a season, so many people lay it slightly deeper than the target.