Gravel Calculator

Enter your area and depth to get volume, weight, bag counts and an estimated cost. Results update instantly as you type — in metric and imperial, side by side.

How to Use the Gravel Calculator

1. Pick a shape. Rectangle for square or rectangular areas, or Circle for round beds, fire pits and round patios.
2. Enter your dimensions. Length, width and depth (or diameter and depth) in any unit — mm, cm, m, in, ft or yd. Everything is converted to metric internally.
3. Choose a material. Pea gravel, crushed stone, river rock or limestone for a typical density, or Custom Density with your supplier’s figure.
4. Set a waste allowance. Add 0–15% (or a custom value) to cover spillage, compaction and uneven ground.
5. Add bag size and price (optional). Pick a bag weight for a bag count, and enter a unit price for an estimated cost.
6. Read your results. Volume, weight, order quantity, bag count and cost update instantly as you type.

How Much Gravel Do I Need?

Gravel quantity starts as a volume. For a rectangular area: volume = length × width × depth. For a circular area, use the radius (half the diameter): volume = π × radius² × depth. Keep every dimension in the same unit so the volume comes out in that unit cubed — metres give cubic metres (m³), feet give cubic feet (ft³). The calculator handles the conversions and shows m³, ft³ and yd³ together. To turn volume into weight, multiply by the material’s density.

Recommended Gravel Depth

How deep you lay gravel depends on what the area has to do. Neutral practical starting points:

• Decorative borders & top-dressing: 40–50 mm (about 1.5–2 in).
• Footpaths & light garden paths: 50–75 mm (2–3 in) over a firm base.
• Landscaping beds & features: 50–100 mm (2–4 in), deeper for larger cobbles and river rock.
• Driveways & parking areas: 100–150 mm (4–6 in), ideally in two compacted layers over a stable sub-base.

Going deeper than about 150 mm rarely helps — gravel becomes hard to walk and drive on. Project requirements vary with soil, traffic and gravel size, so confirm the right depth with your supplier or contractor before ordering.

Cubic Yards vs Tons

Cubic yards (and cubic metres, and cubic feet) measure volume — how much space the gravel fills. Tons measure weight — how heavy it is. They are not interchangeable, because the same volume weighs different amounts depending on the material. A cubic yard of pea gravel and a cubic yard of limestone take up the same space but can weigh different amounts because their density differs. Denser material means more weight per cubic yard, so a ton of dense gravel fills less space than a ton of lighter gravel. That is why this calculator always asks for a material (or a custom density) before converting volume into weight — the density bridges the two.

How Much Does Gravel Weigh?

Gravel weight is volume multiplied by bulk density. The table below shows the typical loose bulk densities used by this calculator. These are estimates — actual weight changes with moisture content, grading, compaction and how the gravel was loaded, so always confirm with your supplier for ordering.

Values are typical loose bulk densities and are affected by moisture and compaction. Use them for planning, then verify the exact figure with your supplier.

Adding Waste

A waste allowance adds a percentage on top of the bare quantity so you order enough. The calculator applies it as order = quantity × (1 + waste%).

• 0% — the exact theoretical amount, no margin. Use only when you can measure precisely and accept running short.
• 5% — a tight margin for clean, simple rectangular areas with good ground preparation.
• 10% — a sensible default for most projects. It absorbs typical spillage, minor compaction and small uneven patches, which is why the calculator selects it by default.
• 15% — a generous margin for awkward shapes, hand-loading, sloping ground or lots of cuts and edging.

You can also enter a custom percentage. Waste is added to both volume and weight, and the bag count is always rounded up from the order quantity.

Estimating Gravel Bags

The bag count depends on the bag weight you select. The calculator divides the order weight (volume × density, plus waste) by one bag’s weight and rounds up: bags = order weight ÷ bag weight, rounded up. Choose a preset (10 kg, 20 kg, 25 kg, 50 lb) or enter a custom bag weight in kg or lb. For reference, one metric tonne is forty 25 kg bags or twenty 50 kg bags. Bulk bags usually hold 800–1,000 kg and are far cheaper per kilo once you need more than about half a tonne — so for larger jobs, compare the bag count against bulk delivery before ordering.

Estimating Gravel Cost

The cost estimate is simply the order quantity multiplied by the unit price you enter: cost = order quantity × unit price. Enter a price and pick the unit your supplier quotes — per metric tonne, per US ton, per m³, per yd³ or per bag — plus a currency (£, $, €). The calculator multiplies the order quantity in that same unit by the price. Prices vary by region, delivery distance and order size, so treat the figure as a planning estimate and get a live quote before buying.

Worked Example

A rectangular driveway section 5 m long × 3 m wide, laid 100 mm (0.1 m) deep, filled with pea gravel (1,680 kg/m³), with a 10% waste allowance, 25 kg bags, and a supplier price of £45 per metric tonne.

You can reproduce this exactly in the calculator above: Rectangle, 5 m × 3 m × 100 mm, Pea Gravel, 10% waste, 25 kg bags, price 45 priced per metric tonne in £.

Gravel questions, answered

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