Measure the actual shape
A straight 60 ft × 10 ft section is 600 ft². Add turnarounds or parking pads as separate rectangles, circles, or known areas. Exclude overlapping parts. For a tapered driveway, split the footprint into smaller shapes you can reasonably measure rather than guessing one width.
Keep layers separate
If the project has a base course and a surface course, calculate each product separately because depth, density, compaction behavior, price, and order increment may differ. Combining them into a single “total gravel” number can make the supplier quote impossible to check.
Loose depth versus finished depth
If 4 in is the depth of loose material after placement, select loose placed depth and do not add a compaction factor. If 4 in is the required compacted finished layer, ask the supplier or installer for the ratio of loose volume to compacted volume for that exact material and method.
Loose delivery volume = compacted geometric volume × supplier loose/compacted factor
For a 600 ft² driveway at 4 in finished compacted depth, the compacted geometric volume is 600 × 4/12 = 200 ft³, or 7.407 yd³. A supplier factor of 1.18 would produce 8.741 yd³ loose. That factor is an example of the math, not a recommended value.
Add allowance only when you choose it
GravelSum starts at 0%. Add a separate allowance for measurement uncertainty or site loss only when your plan calls for it. Do not add a percentage for compaction when you already used a loose-to-compacted factor.
Turn each estimate into an order
- Get loose bulk density for each chosen layer product.
- Confirm whether the supplier quotes cubic yards, US short tons, or metric tonnes.
- For a weight quote, check the volume-to-weight math in the cubic-yards-to-tons converter using the density unit on that quote.
- Enter delivery, minimum order, and order increment for that product.
- Let each layer quantity round up once to its supplier increment.
- Ask the supplier to review both orders against the site and equipment access.
Mulzer Crushed Stone’s aggregate calculator confirms densities vary between materials and its results are estimates; use that point as a warning, not as a density value for either driveway layer.