Gravel Calculator
Compute gravel volume, weight, required depth, coverage area, or bags from area & thickness. Choose a layout mode and output units.
Calculation Steps
Practical Guide
Gravel Calculator: Convert Area, Depth, and Density into Cubic Yards & Tons
A field-tested walkthrough for planning driveways, paths, and drainage: choose depth, set the right density, and convert between cubic yards, tons, and metric units—with worked examples and quick checks.
Quick Start: Get Cubic Yards and Tons in Minutes
- 1 Measure length and width (or enter total area). Choose your depth for the layer you’re installing.
- 2 In the calculator above, pick the unit system (US or metric) and material (pea gravel, #57 stone, crushed rock, etc.). Each material uses a typical bulk density.
- 3 Review outputs for cubic yards / m³ and tons / tonnes. Use the optional compaction/waste percentage to cover settling and spillage.
- 4 For multi-layer builds (e.g., base + top), run the calculator once per layer and add the quantities.
- 5 Round up to practical delivery sizes (e.g., whole tons or truck loads) and verify access/clearances for the delivery truck.
Tip:
For driveways, a common build is 4–6 in of compacted base plus 1.5–2 in of top course. Calculate each layer separately.
Watch-out:
Keep units consistent. If you enter depth in inches, the calculator converts to feet before computing volume—mixing units manually is the #1 source of errors.
Choosing Your Method
Pick the input style that matches how you measure your project.
By Dimensions (Length × Width × Depth)
Best for rectangles and straightforward paths, pads, or parking spots.
- Pros: Highly visual; easy to stake out and verify on site; supports multiple segments.
- Cons: Irregular shapes need splitting into smaller rectangles.
Micro-formula: \(V = L \times W \times d\) (consistent units).
By Total Area (ft² or m² × Depth)
Fastest when plans already give area.
- Pros: Ideal for quoting; fewer fields to enter; great for overlays.
- Cons: Easy to forget to exclude areas you won’t cover (e.g., stepping stones, plant beds).
Micro-formula: \(V = A \times d\).
What Moves the Number: The Big Levers
Your totals are most sensitive to these variables and decisions:
Depth (d): Halving depth halves volume; doubling depth doubles volume. At shallow depths, small changes swing totals a lot.
Bulk density (\\(\\rho\\)): Rounded pea gravel is lighter per yard than dense crushed stone. Density converts volume to tons.
Compaction & waste: Expect 5–15% extra for compaction, raking, and edges. Angular stone compacts more than rounded.
Moisture & fines: Wet, fine-rich blends weigh more than dry, clean stone at the same volume.
Layering strategy: Base vs. top course use different sizes and often different depths—calculate separately.
Unit conversions: Depth in inches must be converted to feet (\(d_{ft}=d_{in}/12\)) before volume in ft³, and 27 ft³ = 1 yd³.
Variables & Symbols
| Symbol | Meaning | Typical Units |
|---|---|---|
| \(L, W\) | Project length, width | ft or m |
| \(A\) | Area | ft² or m² |
| \(d\) | Layer depth (loose) | in or mm (convert to ft or m) |
| \(V\) | Volume | ft³, yd³, or m³ |
| \(\\rho\) | Bulk density of material | tons/yd³ or kg/m³ |
| \(M\) | Mass (order weight) | tons or tonnes |
Core Equations (calculator mirrors these)
\[ V_{ft^3} = L_{ft} \times W_{ft} \times d_{ft}, \quad V_{yd^3} = \frac{V_{ft^3}}{27} \] \[ M_{tons} = \\rho_{\text{(tons/yd}^3)} \times V_{yd^3} \] Metric pathway: \[ V_{m^3} = L_m \times W_m \times d_m, \quad M_{tonnes} = \\rho_{\text{(kg/m}^3)} \times \frac{V_{m^3}}{1000} \]
Worked Examples
These examples illustrate the calculator’s steps and typical rounding choices.
Example A — US Driveway Apron (Crushed Stone)
- Dimensions: \(L=50\\,\\text{ft}\), \(W=12\\,\\text{ft}\)
- Depth: \(d=4\\,\\text{in}=\\tfrac{4}{12}\\,\\text{ft}=0.333\\,\\text{ft}\)
- Density: \(\\rho = 1.4\\,\\text{tons/yd}^3\) (typical crushed rock)
- Waste/compaction: 10%
1
Volume in ft³: \(V=50\\times12\\times0.333\\approx200\\,\\text{ft}^3\).
2
Convert to yd³: \(V=200/27\\approx7.41\\,\\text{yd}^3\).
3
Mass: \(M=1.4\\times7.41\\approx10.4\\,\\text{tons}\).
4
Add 10%: \(\\approx11.4\\,\\text{tons}\\) → order 11.5–12 tons (practical truck increments).
Example B — Metric Garden Path (Pea Gravel)
- Dimensions: \(L=20\\,\\text{m}\), \(W=1.5\\,\\text{m}\)
- Depth: \(d=0.05\\,\\text{m}\) (50 mm)
- Density: \(\\rho=1600\\,\\text{kg/m}^3\) (rounded gravel)
- Waste: 8%
1
Volume: \(V=20\\times1.5\\times0.05=1.5\\,\\text{m}^3\).
2
Mass: \(M=1600\\times1.5/1000=2.4\\,\\text{t (tonnes)}\).
3
Add 8%: \(\\approx2.6\\,\\text{t}\) → round to supplier breakpoints.
Note: Densities vary by quarry, moisture, and gradation. The calculator’s material presets are typical values; you can override with a known density for your supplier.
Common Uses & Depths (Reference)
Depths are for loose-placed material before compaction. Always check your local conditions.
| Application | Material/Size | Typical Loose Depth | Notes on Quantity |
|---|---|---|---|
| Walkway / Patio topping | Pea gravel (3/8") or #8 | 1.5–2 in (40–50 mm) | Light compaction; rake to even out footprints after placement. |
| Driveway top course | #57 / 3/4" angular | 1.5–2 in (40–50 mm) | Install over a compacted base. Angular locks better than rounded. |
| Driveway base layer | 3/4" minus (with fines) | 4–6 in (100–150 mm) | Calculate base and top separately; expect higher compaction. |
| French drain / drainage trench | Clean washed stone (#57) | Varies by trench | Account for pipe OD and fabric wrap; void ratio reduces fines. |
| Under-slab / base course | 3/4" clean or sand-gravel blend | 2–4 in (50–100 mm) | Check specs; vapor barrier and compaction may change totals. |
- Do: Keep length, width, and depth in the same unit family (ft/in or m/mm).
- Do: Enter realistic density for your supplier if known.
- Don’t: Forget separate runs for base vs. top course.
- Don’t: Ignore drainage—graded surfaces shed water and protect the base.
Buying, Logistics & Practicalities
Choosing Material
- Angular vs. rounded: Angular stone interlocks and resists rutting; rounded is more comfortable underfoot.
- Gradation: “Minus” blends include fines (better compaction); “clean” stone drains well but compacts less.
- Color & heat: Darker stone runs hotter in sun; light stone can glare—consider the use and climate.
Delivery & Staging
- Confirm truck access (height, turning radius, ground bearing) and drop location.
- Tarps prevent contamination of soil/grass and simplify cleanup.
- If ordering bags, check per-bag volume (e.g., 0.5 ft³ or 0.67 ft³) to convert from yards.
Code & Specs Notes
- Follow local stormwater and driveway ordinances where applicable.
- For structural fills and under-slab bases, verify gradation and compaction requirements.
- Use geotextile separation on weak subgrades to reduce pumping and stone loss.
FAQs
How many cubic yards are in a ton of gravel?
It depends on density. Many crushed stones run around 1.3–1.6 tons per cubic yard. Invert that to get roughly 0.62–0.77 yd³ per ton. Use your supplier’s density for accuracy.
What depth should I choose for a driveway?
A common approach is 4–6 in compacted base plus 1.5–2 in top course. Heavier vehicles or weaker soils may justify thicker base or geotextile separation.
How much does 1 cubic yard of gravel cover?
Coverage area \(A\) at depth \(d\\,(\\text{ft})\) is \(A=27/d\\,\\text{ft}^2\). At 2 in (\\(d=1/6\\)), 1 yd³ covers about 162 ft²; at 3 in (\\(d=1/4\\)), about 108 ft².
Should I add extra for compaction?
Yes. Add 5–15% depending on material and how aggressively you compact. Angular “minus” mixes require more allowance than rounded pea gravel.
What density should I use if I don’t know?
Use a typical preset in the calculator (e.g., 1.4–1.5 tons/yd³ for crushed stone, ~1.3–1.4 for pea gravel), then adjust when your supplier confirms an exact value.
How many 50-lb bags make a cubic yard?
Convert by volume per bag. If a 50-lb bag is ~0.5 ft³, then \(27/0.5=54\) bags per yd³. If 0.67 ft³, then \(27/0.67\\approx40\) bags. Check the bag label.
Why do my tons differ from a friend’s for the same area?
Density varies by rock type, gradation, moisture, and void content. Two equal volumes can have different weights—always base tons on your supplier’s density.