Driveway gravel is usually sold by the tonne, cubic yard, cubic metre or bulk bag, while the project starts with a length, width and depth. That gap between measurements and supplier units is where most ordering mistakes happen. This guide shows how to measure a driveway, account for more than one layer and use the Handyman Hub gravel calculator to turn the result into a realistic order.
Start by deciding what the driveway needs to do
A light-use parking area, a daily family driveway and a route for delivery vehicles do not necessarily need the same build-up. Before measuring, note the expected vehicle loads, drainage, slope, turning areas and whether the existing ground is soft. The calculator can multiply the dimensions you choose; it cannot decide whether your sub-base, edge restraint or drainage design is suitable.
Measure the plan area
For a simple rectangle, multiply length by width. For an L-shaped or irregular driveway, split the plan into rectangles, calculate each area and add them together. Measure the narrow sections separately rather than using the widest point throughout.
If the width varies, take several width measurements and use an honest average. For example, a driveway that varies from 10 ft to 14 ft can start with an average of 12 ft, but a site with strong curves or tapering should be split into smaller sections.
Depth is the part people underestimate
Enter the compacted layer depth, not the depth of a loose pile. A typical driveway may include a compacted sub-base and a separate surface layer, such as decorative gravel or chippings. The correct depths depend on ground conditions, traffic and local practice.
If a project has two materials, calculate them independently:
- Sub-base: plan its area and compacted depth.
- Surface gravel: plan the same finished area and its own depth.
- Edging or features: calculate extra bays, turning circles or paths separately.
Worked example: a rectangular parking area
Suppose the driveway is 30 ft long and 12 ft wide. The area is 360 square feet. If the compacted sub-base depth is 8 in, convert it to feet: 8 ÷ 12 = 0.667 ft. The sub-base volume is 360 × 0.667, or about 240 cubic feet. Divide by 27 to convert to roughly 8.9 cubic yards before allowing for compaction and site irregularity.
Now imagine a 2 in decorative gravel surface. That is 2 ÷ 12 = 0.167 ft. The surface volume is about 60 cubic feet, or 2.2 cubic yards before allowance. The two orders should remain separate because they are different materials with different densities and prices.
Use the gravel calculator step by step
- Open the gravel calculator.
- Choose feet, metres or the unit system used by your supplier.
- Enter the total length and average width, or calculate separate sections.
- Enter the compacted depth for one layer at a time.
- Review the volume and convert to tonnes, bulk bags or cubic yards using the supplier’s factor.
- Add a visible allowance for compaction, uneven edges and handling.
- Save each layer as a separate line in your quote or materials list.
If the project includes a concrete apron, gate posts or a shed pad, check those quantities separately with the concrete calculator rather than mixing aggregate types into one total.
Compaction and conversion factors
Gravel becomes denser when it is spread and compacted. A supplier may quote by weight while your calculator gives volume. Ask the supplier which conversion factor they use for the exact aggregate, because crushed stone, MOT Type 1, limestone and decorative gravel do not all have the same bulk density.
Do not copy a tonnes-per-cubic-metre figure from a different product. Keep the calculator’s volume and the supplier’s quoted conversion on the same worksheet. If the supplier quotes by bulk bag, ask how many bags they expect for the measured volume and whether that figure assumes loose or compacted material.
Irregular shapes, slopes and turning areas
On a slope, measure the finished plan area horizontally and use the designed layer depth. If the depth changes along the slope, split it into bands or sections. For a turning circle, calculate the circle area using π × radius × radius, then multiply by depth. Add it to the rectangular driveway area rather than inflating the average width.
Curved edges create more cuts and can increase waste. Mark the outline with pegs or paint, measure the sections and keep a sketch with the calculation so a supplier can understand the order.
Drainage and edge restraint matter
Water is one of the quickest ways to damage a gravel driveway. Check where runoff will go, whether the driveway falls toward a building and whether a channel drain or soakaway is needed. Edge restraints stop aggregate spreading into lawns and paths, but they also change the measured area and can create narrow infill strips.
In the UK, check local guidance where a new or replacement driveway could affect surface-water drainage. In the United States, local rules may apply to drainage, setbacks and connections to the public highway.
Common ordering mistakes
Measuring the widest width everywhere
That overstates simple areas and can hide short sections that need separate measurements.
Using loose depth as finished depth
State whether your depth is loose, placed or compacted. Suppliers need to know which assumption your quantity uses.
Combining layers
Sub-base and decorative gravel have different products, densities and prices. Order them as separate lines.
Ignoring access
Confirm whether a tipper can reach the driveway, whether a grab lorry is possible and where a bulk bag can be safely placed.
Ordering by price alone
Compare cost per tonne or cubic metre for the same aggregate type and delivery conditions, not just the headline price.
Practical preparation checklist
- Confirm the property boundary and driveway layout.
- Mark the outline and measure each section.
- Identify soft ground, roots, utilities and drainage routes.
- Confirm the sub-base and surface materials separately.
- Agree compacted depths and conversion factors with the supplier.
- Plan delivery access and safe storage.
- Compact in suitable layers and check finished levels as you go.
The Pavingexpert reference library is useful for comparing paving and sub-base construction details. Product suppliers should still confirm the exact grading, density and coverage of the material you order.
Frequently asked questions
How much gravel do I need for a 20 ft by 10 ft driveway?
Start with the 200 square foot plan area, multiply by the intended compacted depth and convert the volume using the supplier’s factor. If you have a sub-base and surface layer, calculate both separately.
How deep should driveway gravel be?
There is no single depth for every site. Vehicle loads, soil, drainage, aggregate size and whether a sub-base is already present all matter. Use the calculator after the build-up has been confirmed.
How do I convert cubic yards to tonnes?
Use the conversion supplied for the exact aggregate. Density varies between products and moisture conditions, so a generic online factor can be a poor basis for a large order.
Should I allow for compaction?
Yes. Ask the supplier whether their coverage assumes loose or compacted material, then show the allowance separately in your notes.
Can I use the same calculator for a gravel path?
Yes, provided you measure the path area and choose a suitable depth. Split curves, steps and widened seating areas into separate shapes.
Will gravel stop puddles on its own?
Not necessarily. Drainage, falls, sub-base preparation and edge levels determine whether water leaves the surface. Aggregate alone cannot correct a poorly drained formation.
Final driveway order checklist
- Sketch and measure every driveway section.
- Calculate sub-base and surface gravel separately.
- Use compacted depth assumptions and record them.
- Confirm the supplier’s density or bag conversion.
- Add a visible allowance for compaction and irregular cuts.
- Check delivery access, drainage and edge restraint before ordering.
Once the design is confirmed, save the calculator result with the aggregate name, grading, supplier conversion and delivery date. That turns a rough estimate into a quote that can be checked later.
Gravel for driveway: final check
Before ordering, compare the saved calculator result with the supplier’s product coverage, delivery access and agreed compacted depth.
