Walkway gravel volume = net area (sq ft) × selected layer depth (in) / 324, in cubic yards. A rectangular 20 × 3-foot path with a selected 3-inch gravel layer has 0.555556 cu yd of net geometric volume. Calculate the surface and base separately; obtain loose-order conversions and densities for each actual material before buying.
Formula and measurement basis
Area = length × width for a rectangular path.
Cu ft = area × depth / 12.
Cu yd = area × depth / 324.
US short tons = ordered loose cu yd × matching lb/cu yd / 2,000.
Measure the area inside the edging that actually receives the layer. For varying widths, bends, landings and intersections, divide the target into non-overlapping shapes or measured strips. Do not count junctions twice. Keep unrounded values through the takeoff and apply the supplier’s actual sales increment only at the end.
Net volume chart: 3-foot-wide rectangular path
| Length | Area | At selected 2 in | At selected 3 in |
|---|---|---|---|
| 10 ft | 30 sq ft | 0.185 cu yd | 0.278 cu yd |
| 20 ft | 60 sq ft | 0.370 cu yd | 0.556 cu yd |
| 50 ft | 150 sq ft | 0.926 cu yd | 1.389 cu yd |
| 100 ft | 300 sq ft | 1.852 cu yd | 2.778 cu yd |
These are geometric volumes with no reserve or compaction conversion. For a uniform 4-foot-wide path, recompute using area = length × 4, rather than scaling a rounded chart entry. The two depth columns are choices for calculation, not a universal path specification.
Depth and base: keep the source designs distinct
The supplier Hello Gravel describes a 2–3-inch gravel surface over fabric and an optional 2–3-inch crushed-stone/road-base foundation for wet areas.1 This is supplier guidance, not a design for every soil, slope or use.
This Old House describes a different build: a 4-inch excavation, about 2.5 inches of stone pack placed before tamping, then fabric and gravel filled to about 0.5 inch below the top of the edging. It describes 3–4 feet as a typical width.2 Its 2.5-inch placement is followed by compaction; the article does not establish a loose-to-compacted multiplier or a universal finished surface thickness.
Do not combine one source’s excavation depth with another source’s surface thickness and call it the same build. Determine the finished elevation, compacted base thickness, surface thickness and edging position together. Soil support, drainage and intended use can change the needed section. A quantity table does not certify stability or accessibility.
Three checked examples
1. Surface only: 20 × 3 ft at 3 inches
Net area = 60 sq ft. Volume = 60 × 3 / 12 = 15 cu ft = 0.555556 cu yd. A hypothetical chosen 10% handling reserve would give 16.5 cu ft = 0.611111 cu yd. That reserve is a selected example, not a verified universal settling factor. Obtain any required material conversion separately.
2. A 50 × 3-foot surface, converted to weight
At 2 inches, net volume = 150 × 2 / 324 = 0.925926 cu yd; at 3 inches, it is 1.388889 cu yd. The TRORC-hosted reference chart lists “Pebbles (3/8 pea)” at 2,700 lb/cu yd.3 Using that reference density and treating the calculated volumes as the matching loose volume gives 2,500 lb (1.25 short tons) and 3,750 lb (1.875 short tons) respectively. These are examples, not measured weights for a supplier’s product.
Using rounded 0.93 and 1.39 first would give 2,511 and 3,753 lb, so use full precision. If the intended placed volume requires a different loose order quantity, convert that quantity before multiplying by loose density. A generic “1–2 tons” claim does not settle product, moisture, compaction or order increment.
3. Separate base and surface: 20 × 4 ft
For a selected design with 2 inches of surface and 2.5 inches of finished base, area is 80 sq ft. Net surface = 80 × 2 / 324 = 0.493827 cu yd. Finished base geometry = 80 × 2.5 / 324 = 0.617284 cu yd. Their selected finished thicknesses sum to 4.5 inches. This is our quantity example, not the This Old House 4-inch-excavation recipe. The excavation depends on actual final elevations; the base order requires its own loose-to-finished conversion and density.
Keep these inputs separate
| Input | What to verify |
|---|---|
| Net geometry | Actual area and each layer’s specified thickness |
| Loose/finished conversion | Supplier or installation specification; no automatic 1.25 multiplier |
| Density | Actual product, moisture and loose/compacted basis |
| Handling reserve | A separately selected allowance, not an assumed compaction percentage |
| Sales increment | Actual bulk increment or labeled bag yield |
| Loaded weight | Final ordered quantity and containers; vehicle capacity is a separate check |
Edging and fabric quantities
This Old House uses edging to contain loose gravel and keeps the surface below its top.2 Measure the actual edge runs, including curves, rather than deriving all edging from rectangular area. A straight 20-foot path edged on two sides starts with 40 linear feet before end closures, connections and cutting.
Fabric quantity is a layout problem as well as an area problem. Use the actual roll width, required product-specific overlap, turns and cuts. The source shows overlaps at relief cuts on curves, but does not establish a universal “few inches” rule for every fabric.2
FAQ
How much for each 10 feet of a 3-foot-wide path?
At selected depths of 2 and 3 inches: 0.185185 and 0.277778 cu yd net. Recompute from the full area for the entire path before rounding the order.
Does the base use the same density as the surface?
Not automatically. Stone pack, road base, pea gravel and decomposed granite can have different density and placement bases. Quote and calculate each product separately.
Should I always add 5–10%?
No universal percentage is established here. Separate material conversion, selected reserve and actual sales rounding rather than applying one percentage to every layer.
Can I turn pounds of bagged gravel into volume?
Use the actual labeled yield or product-specific density. A bag’s weight alone does not establish cubic feet.
Related tools and guides
Gravel calculator | Decomposed-granite quantities | Bagged-gravel quantities | Measure an irregular area
Sources
- Hello Gravel: Gravel Path Materials (supplier-specific surface depth and optional wet-area base)
- This Old House: How To Lay a Budget-Friendly Gravel Path (example build sequence, pre-tamping stone pack, edging and fabric cuts)
- Material Weight: Pounds per Cubic Yard, hosted by TRORC (reference 3/8 pea-pebble weight, not a measured batch density)