🪨 Gravel & Base Material Calculator

Estimate how much gravel or base material you need for driveways, walkways, patios, and trenches. Enter your areas and depth to see volume in cubic feet and cubic yards, plus an approximate tonnage and 0.5 ft³ bag count.

Gravel calculator results

Enter dimensions for at least one area or trench, then choose Calculate Gravel Volume & Tons to see the total volume, cubic yards, tons, and approximate bag count.

Gravel volume breakdown by shape

After you run a calculation, this section shows the volume from each shape and the combined total so you can double-check your inputs and share them with your supplier.

Gravel calculator inputs and key terms

This calculator focuses on common gravel and base material uses such as driveways, walkways, patios, and trenches. Here's how each input works and why it matters.

• Rectangular areas: Use this for straight-run driveways, patios, parking pads, or rectangular walkways. Enter the length and width in feet, depth in inches, and how many areas of that size you have.
• Circular areas: Ideal for round patios, fire pit areas, or circular plant beds. Enter the diameter in feet, the gravel depth in inches, and the number of identical circular areas.
• Trenches: Use this for drainage lines, utility trenches, or French drains. Enter length and width in feet and depth in inches. The calculator treats the trench as a rectangular prism.
• Depth (inches): How thick the gravel layer is. Light paths may use 2–3" of gravel, while driveways and base layers under pavers often use 4–6" or more.
• Waste factor (%): Extra volume to account for compaction, uneven excavation, and spillage. Many projects use 5–10% waste. Steep slopes or rough excavation may justify a higher value.
• Cubic foot (ft³): A volume equal to a cube 1 foot on each side. Good for thinking about smaller projects and bagged material.
• Cubic yard (yd³): A volume equal to 27 cubic feet (3′ × 3′ × 3′). Most bulk gravel suppliers quote prices in cubic yards.
• Tons of gravel: An estimate of total weight based on an average density of about 1.5 tons per cubic yard of compacted gravel. Specific products can be denser or lighter.
• 0.5 ft³ bags: Many home center bags contain roughly 0.5 cubic feet of gravel. The calculator estimates how many such bags you'd need when not buying bulk.

Formulas used in the Gravel & Base Material Calculator

These formulas match typical estimating practices for gravel, crushed stone, and base material. All dimensions are converted to feet before computing volume.

1. Rectangular area volume

Let:
L = length (ft)
W = width (ft)
D = depth (inches)
N = number of identical rectangular areas
Convert depth to feet:
Dft = D ÷ 12
Then:
Rectangular volume (ft³) = L × W × Dft × N

2. Circular area volume

Let:
Dia = diameter (ft)
D = depth (inches)
N = number of identical circular areas
Convert to radius and depth in feet:
R = Dia ÷ 2 (ft)
Dft = D ÷ 12
Area of a circle:
Area = π × R²
Volume:
Circular volume (ft³) = π × R² × Dft × N

3. Trench volume

Let:
L = trench length (ft)
W = trench width (ft)
D = depth (inches)
N = number of trenches
Convert depth to feet:
Dft = D ÷ 12
Treat the trench as a rectangular prism:
Trench volume (ft³) = L × W × Dft × N

4. Total volume and waste factor

Let:
Vrect, Vcircle, Vtrench = volumes for each shape type in ft³
p = waste factor (%) as a whole number (for example, 10 for 10%)
Total ft³ (before waste) = Vrect + Vcircle + Vtrench
Waste multiplier:
k = 1 + (p ÷ 100)
Total ft³ with waste = Total ft³ × k
Convert to cubic yards:
Total yd³ = Total ft³ ÷ 27
Total yd³ with waste = Total ft³ with waste ÷ 27

5. Tons and bag counts

Let:
ρ = average gravel density in tons per cubic yard (approx. 1.5)
Vyd = total volume in cubic yards with waste
Vft = total volume in cubic feet with waste
Vbag = volume per bag (ft³), about 0.5 ft³
Tons:
Tons ≈ Vyd × ρ
Bag count:
Bags ≈ ceil(Vft ÷ Vbag)

These density and bag volume values are typical approximations. Always check actual product data sheets for exact weights and coverage.

Gravel & Base Material Calculator FAQs

• How accurate is this gravel calculator for real projects?
  The volume math is exact for the shapes and dimensions you enter. The tonnage and bag counts are estimates based on typical gravel density and bag sizes. Real-world results can vary with rock type, moisture, and compaction, so most contractors round up slightly and add a waste factor on top of the calculated volume.
• What depth of gravel should I use for driveways and paths?
  Many light-duty paths use 2–3" of gravel. Residential driveways and base layers under pavers often use 4–6" or more, sometimes in multiple lifts. It's always best to confirm design thickness with local building practices, soil conditions, and any engineering requirements for your project.
• What density does this calculator assume for gravel?
  This calculator assumes an average compacted gravel density of about 1.5 tons per cubic yard, which is typical for many crushed stone and base materials. Some materials are heavier or lighter, so ask your supplier for the exact density if you need a precise tonnage estimate.
• Should I adjust the waste factor for my project?
  Yes. Flat, simple projects with accurate excavation may only need 5–10% waste. Uneven ground, hand-dug trenches, or projects with slopes and curves may need more. The waste factor helps ensure you have enough material even after compaction and small layout changes.
• Is it better to buy gravel by the ton, cubic yard, or by the bag?
  For driveways, larger patios, and deep base layers, bulk deliveries by the cubic yard or ton are usually more economical. Bags are convenient for small areas, decorative stone, or hard-to-reach spots. This calculator shows both yards and bag counts so you can compare options.
• Can I use this calculator for other materials like crushed stone or mulch?
  Yes, the volume calculations work for any material that fills the same space. However, the density (tons per cubic yard) and bag volume may differ for mulch, sand, or decorative rock. For the best tonnage estimate, ask your supplier for the specific density of the material you plan to use.