Gravel and Mulch Calculator
The gravel and mulch calculator works out exactly how much bulk material your landscaping, garden, or construction project needs. Enter your area's shape, dimensions, and depth, pick a material, and it returns the volume, weight, number of bags, and an estimated cost.
It is built for anyone ordering loose-fill aggregates: homeowners spreading mulch on garden beds, DIYers laying a gravel driveway or paver base, and contractors estimating crushed stone or sand by the cubic yard and ton. Choose from ten common materials or enter a custom density, and switch freely between metric and imperial units.
How to Use the Calculator
Choose your unit system
Use the Unit System toggle to switch between Metric (m, cm, kg) and Imperial (ft, in, lbs). If you switch after entering values, everything is converted automatically.
Select the area shape
Pick the tab that matches your area: Rectangle (length and width), Circle (diameter), Triangle (base and height), Trapezoid (top width, bottom width, height), or L-Shape (Section A and Section B). A labeled diagram shows which dimension goes where.
Enter depth and material
Type the desired depth, then pick a material from the dropdown to apply its density automatically. A recommended depth range appears below the field for the material you choose. For anything not listed, select Custom and enter the density in kg/m³.
Adjust the settings
Fine-tune the Waste Factor (default 10%) for spillage and compaction, set the Bag Size (default 25 kg) to match your supplier, and add a Price / Bag to get a cost estimate.
Read the results
The results card updates live with Area, Volume (including waste), Weight, Bags Needed, and Estimated Cost when a price is entered.
Add multiple sections
For projects that cover several areas, press Add Section to save the current calculation, then change the shape, dimensions, or material and add more. The Total Summary combines volume, weight, bags, and cost across all sections.
Features
Five Area Shapes
Calculate for rectangles, circles, triangles, trapezoids, and L-shaped areas, each with an interactive diagram that labels the dimensions to measure.
Ten Material Presets
Pick gravel, pea gravel, crushed stone, sand, topsoil, mulch, bark, compost, river rock, or lava rock, each preset with a realistic density value.
Custom Density
Material not on the list? Choose Custom and enter any density in kg/m³ from the product packaging or supplier spec sheet.
Metric and Imperial Units
Switch between m, cm, kg and ft, in, lbs with one tap. Entered values auto-convert, so you never need to re-key measurements.
Depth Recommendations
Each material shows a suggested depth range and typical uses, so you can pick a sensible depth for driveways, beds, or base layers.
Adjustable Waste Factor
The default 10% allowance covers spillage, compaction, and uneven ground, and the results show exactly how much extra volume it adds.
Bag Estimation
Set your supplier's bag size and the calculator tells you how many bags to buy, always rounded up so you never come up short.
Cost Estimation
Enter a price per bag to see the estimated total cost instantly, making it easy to budget before you head to the store.
Multi-Section Totals
Add each area as its own section with a different shape and material, and a summary card totals the volume, weight, bags, and cost.
Volume, Weight, and Tons
See volume in cubic yards or cubic meters and weight in tons, pounds, or kilograms, so the figures match how suppliers sell material.
Frequently Asked Questions
How many cubic yards of gravel or mulch do I need?
Enter your area's shape and dimensions, set the depth, and switch to Imperial units. The Volume result shows the amount in cubic yards (with the metric equivalent in parentheses), already including your waste factor.
How many tons is a cubic yard of gravel?
It depends on density. Most gravel and crushed stone weigh roughly 1.3 to 1.5 tons per cubic yard, while lighter materials such as mulch are far less. The calculator handles this for you: select the material and the Weight result reports the total in tons, pounds, or kilograms.
How deep should gravel or mulch be?
The calculator shows a recommended range under the depth field for each material. As a guide: gravel driveways need about 4–6 inches (10–15 cm) for vehicles and 2–3 inches (5–8 cm) for walkways; mulch for garden beds is 2–4 inches (5–10 cm); sand for a paver base is 1–2 inches (2.5–5 cm).
How do I measure an irregularly shaped area?
Break the area into simpler shapes. An odd garden bed can often be approximated as a rectangle plus a triangle. Calculate one shape, press Add Section, then switch to the next shape and add it too. The Total Summary gives you the combined amount.
What waste factor should I use?
The default 10% suits most projects. Raise it to 15–20% for uneven terrain, many curves or obstacles, or materials that compact heavily. For flat, uniform surfaces you can lower it to around 5%.
What is the difference between volume and weight?
Volume (in m³ or yd³) is how much space the material takes up; weight (in kg, lbs, or tons) is how heavy it is. The same volume of different materials weighs very differently: 1 m³ of mulch is about 400 kg, while 1 m³ of crushed stone is about 1,600 kg.
How accurate are the density values?
The presets are typical averages for each material. Actual density varies with moisture, particle size, and compaction. For critical orders, confirm the density with your supplier and enter it using the Custom option.
What does "Bags Needed" mean?
It is how many bags of your chosen size (default 25 kg) you need to buy, always rounded up so you have enough. Adjust the Bag Size field to match what your local store sells.
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