Read the result before you order
Volume is the measurement. Tons and bags translate that volume into the units a seller may quote.
Cubic yards tell you the space to fill
Square feet alone cannot tell you how much rock to buy. The planned finished depth determines volume: square feet × inches of depth ÷ 324. A cubic yard contains 27 cubic feet.
Work from cubic yardsTons depend on the actual product
The calculator starts with a planning density from the selected project. Stone type, grading, moisture, and supplier handling change weight per cubic yard. Confirm the seller’s factor for a ton-based quote.
Check rock densityBags depend on the volume label
The bag result assumes 0.5 cubic foot per bag and rounds up to whole bags. A bag sold by weight alone needs its own coverage or volume information; 50 pounds is not automatically 0.5 cubic foot.
Plan a bag purchase30 ft × 10 ft at 3 in deep
That is 300 square feet and 2.78 cubic yards of placed rock. Add the default 10% allowance to plan for 3.06 cubic yards. At 1.35 short tons per cubic yard, that is about 4.13 short tons, or 165 half-cubic-foot bags.
Before placing the order: Keep the calculated volume, then replace the default density with your supplier’s figure for this stone. Ask for a delivered price and check the actual bag volume if you are buying packaged rock.
Measure the surface and the layer separately
Sketch the area before opening a supplier quote. A little time with a tape measure prevents a large error in the order.
- Find the net area. For a rectangle, multiply length × width in feet. Divide an L-shaped space into rectangles and add them. Do not count a patio, stepping stones, or other space that stays bare.
- Set the finished depth. Measure the rock layer you want after placement. If you are refreshing an existing bed, estimate only the added thickness.
- Calculate each depth separately. A shallow border and a deep path should be separate zones. Add their cubic yards at the end, then choose an allowance for irregular edges or low spots.
The same 100 square feet at three depths
These are geometric examples, not universal depth recommendations. Pick a finished depth that fits your stone size and the layer you are building.
| Finished depth | Net volume | With 10% extra | 0.5-cu-ft bags |
|---|---|---|---|
| 2 in | 0.62 yd³ | 0.68 yd³ | 37 |
| 3 in | 0.93 yd³ | 1.02 yd³ | 55 |
| 4 in | 1.23 yd³ | 1.36 yd³ | 74 |
Bag counts use the unrounded cubic-foot volume and round up to a whole bag. One cubic yard covers 108 square feet at exactly 3 inches before any allowance; for the reverse question, use the rock coverage calculator.
Check the layer you are actually buying
Decorative bed
Count the exposed soil area, then choose a layer that covers at the size of your stone. A 3-inch setting is a starting measurement, not a promise that large river rock will hide soil at that depth.
Rock and fabric can reduce some weeds, but dust and organic matter eventually collect above them. See the river rock calculator and weed control guide.
Driveway layer
Estimate a new base and a surface layer separately. The calculator’s driveway preset represents only the entered layer; it does not design a complete driveway for your soil, drainage, traffic, and compaction needs.
For a specific gradation and project, use the driveway rock calculator or crushed stone calculator.
Drainage trench
Measure the width, length, and height of the stone-filled zone, rather than assuming the entire trench is rock. Pipe and other layers occupy space. Drainage details and stone grading should follow your site plan.
Use the drain rock calculator for a more specific takeoff.
What to tell the rock supplier
Bring the name and size of the stone, your calculated cubic yards, chosen allowance, and the depth of each layer. Then ask these questions before paying:
- Is this product sold by the cubic yard, U.S. short ton, or bag?
- What is this product’s actual tons-per-cubic-yard factor or coverage at my depth?
- What are the minimum order, delivery charge, access needs, and dump location?
- If bagged, what volume does each bag contain, and how many bags are on a pallet?
Compare the delivered bulk quote against bags using the same volume. The bulk versus bagged guide helps with that decision.
Frequently asked questions
How much rock do I need for a 10 × 10 foot area?
At a finished depth of 3 inches, a 10 × 10 foot area needs 0.93 cubic yard before extra material. With a 10% allowance, it needs about 1.02 cubic yards, equal to 55 bags if each bag contains 0.5 cubic foot. Tonnage depends on the actual stone.
How many tons are in a cubic yard of rock?
There is no single conversion for every rock. The calculator starts with a planning density for each project preset. At 1.35 U.S. short tons per cubic yard, one cubic yard weighs about 2,700 pounds. Ask your supplier for its product-specific conversion before a weight-based order.
Should I add 10% extra rock?
A 10% allowance can cover small measurement errors, irregular edges, and shallow low spots. It is optional, not a substitute for measuring a seriously uneven surface. Enter 0% if you have accurate dimensions and your supplier can deliver a small top-up.
How do I estimate rock for an L-shaped bed or several areas?
Split the space into rectangles, calculate each uncovered area at its own finished depth, and add the volumes. Subtract patios, pavers, or planting islands that will not receive rock. Use the calculator once per zone when depths differ.