Gravel Calculator Widget
Put a gravel and aggregate calculator on a quarry, landscape-supply or driveway page. Customers enter a rectangular or round area and a depth, pick the material, and get the volume, the weight in short tons or tonnes and the number of bags or bulk bags to order.
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Under the widget on your page: Powered by A2Z Tools
Embed code
<iframe src="https://a2z.tools/embed/w/gravel-calculator" title="Gravel Calculator by A2Z Tools" width="100%" height="760" style="border:0;width:100%" loading="lazy" allow="clipboard-write"></iframe>
A plain iframe. Works everywhere, including site builders that strip scripts. Adjust height if your content needs more room.
<div data-a2z-widget="gravel-calculator" data-height="760"></div> <script async src="https://a2z.tools/embed.js"></script>
Adds a small script (what it does) that sizes the widget to fit its content, loads it lazily and keeps it isolated from your page's CSS.
Works with
How it works
Volume is the area - length x width, or pi x radius squared for a circle - times the depth. Aggregates are sold by weight, so the widget multiplies the volume by a dry unit weight from the Washington State DOT Design Manual: 3,100 lb per cubic yard for loose ballast, 2,950 for loose crushed base course, 2,850 for loose top course, 3,700 for compacted gravel base and about 3,400 for material that is essentially all sand. A 20 x 10 ft driveway patch 4 in deep is 66.7 cu ft, or 2.47 cubic yards; as loose ballast that weighs 7,654 lb, 3.83 short tons. Metric mode converts the same figures to tonnes per cubic metre (3,100 lb/yd³ is 1.839 t/m³). Bag counts use either the bag's volume (0.5 cu ft) or its weight (50 lb, 20 kg, 25 kg, 1 t bulk bag). For pea gravel, decomposed granite or topsoil, choose Other and enter the density your supplier quotes; values outside 0.2-4 t/m³ are refused as a unit mix-up.
Calculation method
- Volume = length x width x depth (circle: pi x (diameter / 2)^2 x depth)
- Weight = volume x unit weight; 1 yd3 = 0.764555 m3; 1 short ton = 2,000 lb = 907.18 kg
- Unit weights (WSDOT M 22-01 ch. 620, dry): ballast 3,100 lb/yd3 loose; crushed base course 2,950 loose; top course 2,850 loose; gravel base 3,700 compacted; essentially-all-sand 3,400 compacted
- Bags = ceil(volume / bag volume) or ceil(weight / bag weight)
Worked examples
Driveway top-up
Inputs: 20 x 10 ft; 4 in deep; loose ballast; 0.5 cu ft bags
Result: 2.47 yd³; 3.83 short tons; 134 bags
20 x 10 x 4/12 = 66.7 cu ft = 2.469 yd³ x 3,100 = 7,654 lb; 66.7 / 0.5 = 133.3 -> 134.
Metric patio base
Inputs: 6 x 3 m; 10 cm; loose ballast; 1 t bulk bags
Result: 1.8 m³; 3.31 tonnes; 4 bulk bags
1.8 m³ x 1.839 t/m³ = 3.31 t, rounded up to 4 bags.
Round fire-pit area
Inputs: 4 m diameter; 5 cm; density 1.6 t/m³; 25 kg bags
Result: 0.628 m³; 1.01 tonnes; 41 bags
pi x 2² x 0.05 = 0.628 m³ x 1.6 = 1.005 t / 25 kg = 40.2 -> 41.
Limitations
- Unit weights are one agency's figures for its own specification materials; local stone, moisture and grading differ, so confirm with the supplier.
- Pea gravel, decomposed granite and topsoil have no built-in preset - their density must be entered.
- Flat, level areas only; sloped or irregular areas need splitting into pieces.
Where publishers use it
- Quarries and aggregate yards that sell by the ton or tonne
- Landscape suppliers listing bagged and bulk-bag gravel
- Driveway, path and patio-base how-to articles
- Drainage and French-drain guides
- Garden-design blogs planning gravel gardens and play areas
Questions
How many tons of gravel do I need?
Work out cubic yards (length x width x depth in feet / 27), then multiply by the material's weight. 2.47 yd³ of loose ballast at 3,100 lb/yd³ is 7,654 lb, about 3.8 short tons; the same volume of crushed base at 2,950 lb/yd³ is 3.6 tons.
How much does a cubic yard of gravel weigh?
WSDOT lists 2,850-3,100 lb per cubic yard for loose crushed surfacing and ballast as delivered, and 3,700 lb once compacted. Moisture, grading and rock type move these figures, so your supplier's number wins.
Why order more loose gravel than the compacted depth?
Compaction squeezes out voids. Base course weighs 2,950 lb/yd³ loose and 3,700 compacted in WSDOT's table, so each compacted cubic yard needs about 1.25 loose yards. Picking 'compacted' makes the weight right for a finished depth.
How deep should a gravel driveway be?
Depth is a design decision that depends on traffic and the ground; driveways are usually built in layers, coarser stone below and finer on top, over a firm sub-base. Enter each layer separately if they are different materials.
How many bags of gravel make a cubic yard?
A cubic yard is 27 cu ft, so 54 bags of 0.5 cu ft. By weight, a yard of loose ballast at 3,100 lb fills 62 bags of 50 lb.
What about pea gravel or decomposed granite?
Their densities vary more with moisture and fines, so the widget has no fixed preset. Choose Other and enter the figure on your supplier's ticket, in lb per cubic yard or tonnes per m³.
Sources
- Design Manual M 22-01, Chapter 620 - Unit Dry Weight, Gravel Base and Surfacing - Washington State Department of Transportation . Truck measure (loose): ballast 3,100 lb/cy, crushed surfacing top course 2,850, base course 2,950; compacted 3,700-3,900; about 3,400 lb/cy for material that is essentially all sand.
Cite or recommend this tool
If you reference this tool in an article, course or documentation, these formats are ready to copy. They are optional - nothing is added to your site unless you paste it.
A2Z Tools Gravel Calculator https://a2z.tools/embed/gravel-calculator
<a href="https://a2z.tools/embed/gravel-calculator">A2Z Tools Gravel Calculator</a>
[A2Z Tools Gravel Calculator](https://a2z.tools/embed/gravel-calculator)
Gravel Calculator by A2Z Tools - https://a2z.tools/embed/gravel-calculator
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