Landscape & Groundwork
River Rock Calculator
Find the cubic yards, tons and material cost for your river rock bed.
Enter your measurements
Results update as you type.
About this calculator
River rock is a rounded, mixed-size decorative stone. Enter the bed dimensions, an area with depth or a known volume, then add an order allowance and the supplier's bulk density to estimate weight.
How to use this calculator
- Measure the bed, dry creek or border area.
- Check the named dry-rock supplier example beside the density field, then replace it with the density for your actual material and volume basis.
- Add an allowance for irregular edges and depth variation.
- Compare net and order volumes before delivery.
Formula
Net volume = length × width × depth (or area × depth, or entered volume)
Order volume = net volume × (1 + allowance ÷ 100)
Weight = order volume × supplier density — only when density is supplied
Assumptions
- Mixed rock sizes leave voids; volume is geometric and no void ratio is guessed.
- Bulk density varies with size mix and moisture; the default is editable.
- Weight appears only when a density is entered.
- The editable density is a named supplier example. Grading, moisture and compaction can change the weight.
Volume for a 6 × 10 ft bed
| Depth | Volume before allowance |
|---|---|
| 2 in | 0.370 yd³ |
| 3 in | 0.556 yd³ |
| 4 in | 0.741 yd³ |
Calculated geometry; irregular ground and large stones can affect practical coverage.
Common mistakes
- Mixing depth in inches with area in square feet before converting units.
- Using a loose or dry supplier density for a different compacted or wet material.
- Applying extra order volume twice, or treating it as a compaction model.
Worked example
Try it: press “Load example” above the form.
12 ft × 9 ft × 3 in is exactly 1 yd³. At the illustrative density of 1.4 US short ton/yd³, weight is 1.4 US short tons before any allowance.
Limitations
Quantities are geometric planning estimates. Confirm the material, dry/loose or compacted basis, delivery minimum and density with your own supplier. The allowance is extra volume, not a compaction model.
Frequently asked questions
How should I measure an irregular river rock bed?
Divide it into rectangles, estimate each section at its average depth and add the volumes. Large rocks and uneven ground make depth less uniform, so confirm the method with the supplier.
Does rock size affect coverage?
Yes. Larger stones need a different practical layer depth and leave larger voids. The calculator uses your chosen depth; it does not choose a stone size or prescribe a coverage thickness.
What does the worked example show?
12 ft × 9 ft × 3 in is exactly 1 yd³. At the illustrative density of 1.4 US short ton/yd³, weight is 1.4 US short tons before any allowance.
Which assumptions should I check before using the result?
Quantities are geometric planning estimates. Confirm the material, dry/loose or compacted basis, delivery minimum and density with your own supplier. The allowance is extra volume, not a compaction model.
Sources
Sources explain the methods and any named product presets. Check your product label where coverage, yield or density differs.
- Inch Calculator: Gravel
- NIST: Revised Unit Conversion Factors
- Triangle Landscape Supplies: dry bulk weights
Named supplier examples: rock 2,800 lb/yd³, sand 2,500 lb/yd³, soil 2,000–2,600 lb/yd³. These do not specify every material. Checked 8 November 2026.
Calculation documentation · Updated 2026-11-11 · Version 1.6.4. Estimates are planning aids. Confirm quantities, coverage and prices with your supplier before purchasing. Found an error? Report it.
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