Calculator
Choose a shape, enter dimensions and depth, then review volume, weight, and costs.
Example data table
| Area (ft²) | Depth (in) | Waste (%) | Volume (yd³) | Weight (tons) | 50 lb bags |
|---|---|---|---|---|---|
| 100 | 2 | 8 | 0.686 | 0.926 | 38 |
| 200 | 3 | 10 | 1.833 | 2.475 | 99 |
| 350 | 2.5 | 7 | 2.301 | 3.106 | 125 |
Examples assume about 100 lb/ft³ density and round bags up.
Formula used
- Area depends on shape: Rectangle: A = L × W • Circle: A = πr² • Triangle: A = ½ × B × H
- Depth conversion: inches → feet = in ÷ 12, centimeters → feet = cm ÷ 30.48
- Volume: V(ft³) = Area(ft²) × Depth(ft) × (1 + Waste%/100)
- Unit conversions: yd³ = ft³ ÷ 27, m³ = ft³ ÷ 35.3147
- Weight: Weight(lb) = V(ft³) × Density(lb/ft³), tons = lb ÷ 2000
- Bags: Bags = Weight(lb) ÷ BagWeight(lb), then round up
- Cost: Cost = Quantity × Rate, based on the chosen purchase method
Density and settling differ by supplier; measure a test load when possible.
How to use this calculator
- Select the shape that matches your bed or path.
- Pick a dimension unit, then enter the required measurements.
- Set the depth and add a reasonable waste allowance.
- Choose a rock size or enter a custom density.
- Enter prices for yards, tons, or bags to compare costs.
- Press Calculate, then download a CSV or PDF if needed.
Use this guide to size river rock coverage, compare purchase methods, and document quantities for garden projects.
Measure Area With Confidence
River rock coverage starts with accurate area. Measure beds, paths, or circles, then choose feet or meters. The calculator converts shapes into square feet automatically. For irregular layouts, use custom area from a site plan or string‑line estimate. Better area input reduces overbuying and uneven top layers during purchasing decisions.
Choose a Practical Depth
Depth controls both appearance and weed suppression. Decorative applications often use 2–3 inches, while high‑traffic paths may use 3–4 inches. The tool converts inches or centimeters into feet for volume. Add a waste allowance of 5–12% to cover settling, edging, and minor grade changes. Consider 4 inches for heavy use.
Understand Volume Units
Volume is computed as Area × Depth, then adjusted for waste. Results show cubic feet and cubic yards, where 1 yd³ equals 27 ft³. Many landscape suppliers sell by the yard, so this conversion helps compare quotes. Use the same measurement unit for all dimensions to avoid errors very quickly.
Translate Volume Into Weight
Weight estimates use density, typically 95–105 lb/ft³ for rounded river rock, depending on size and moisture. The calculator provides tons by dividing pounds by 2,000, helpful when suppliers price by ton. If your quarry lists bulk density, enter it as a custom value for higher accuracy from the supplier directly.
When Bags Make Sense
Bags are convenient for small gardens and tight access areas. Enter your bag weight, commonly 40–50 lb, and the calculator rounds up to whole bags. Bagged material can cost more per cubic yard, but it simplifies transport and storage. Compare bag totals against yard and ton estimates for quick projects.
Compare Pricing Methods
Pricing fields let you test different purchasing methods. A yard price estimates cost directly from volume. A ton price uses the weight estimate, which changes with density. A bag price multiplies rounded bags by per‑bag cost. Use all three outputs to pick the most economical supplier and delivery option overall.
Improve Accuracy With Installation Planning
Planning details improve results. Compact the base, install edging, and keep depth consistent across the surface. For drainage, avoid burying rock in soil; use landscape fabric where appropriate. If slopes exist, increase waste slightly. Add extra for curves. Always check local delivery minimums, then round your order to practical increments.
Use Reports for Budget Control
Use the downloadable reports to document quantities for bids or DIY checklists. CSV works for spreadsheets and unit‑cost comparisons, while PDF prints cleanly for site use. Save one report per area section and sum totals. Accurate records help control budget, reduce leftovers, and keep installation on schedule for each phase.
Quick answers to common river rock coverage questions.
What depth is best for river rock in beds?
Most beds look natural at 2–3 inches. For footpaths, 3–4 inches improves coverage and stability. Deeper layers can shift unless edged and compacted. Use a waste allowance to account for settling.
Why does the calculator ask for density?
Suppliers sell by volume or weight. Density converts cubic feet into pounds and tons. Rounded, dry river rock often ranges around 95–105 lb/ft³, but moisture and size change it. Enter your supplier’s value for tighter estimates.
How much waste should I add?
Use 5% for flat, well‑edged areas. Use 8–12% for uneven grades, curves, or hand‑spreading. Add more if you expect settling into soil or gaps between pavers. Ordering a little extra prevents delays.
Should I buy by yards, tons, or bags?
For medium and large projects, bulk by the yard is usually cheapest. If a supplier quotes by ton, compare using the ton output. Bags help small sections or tight access. Compare all three cost lines before purchasing.
Can I use square meters and centimeters?
Yes. Select meters for dimensions and centimeters for depth. The calculator converts to internal feet units, then shows results in yards, cubic meters, pounds, kilograms, and tons. Keep units consistent within each field group.
How accurate are the bag counts?
Bag counts are rounded up to whole bags, so they err on the safe side. Accuracy depends on true bag weight and rock density. If bags are labeled by volume instead of weight, use the yard estimate instead.
What if my area is an irregular shape?
Break the space into simple rectangles, circles, or triangles and add the areas. Or measure total area from a drawing, GIS, or a lawn‑measurement app and enter it as custom area. This approach works well for curved beds.
Measure accurately, add waste, and order rock with confidence.