Quick answerA gravel calculator estimates the volume and weight of aggregate needed to cover a rectangular area at a chosen depth. It can also add a waste allowance for compaction, uneven ground, and handling losses.
Estimating gravel for a project
Start with the finished length and width of the area, then choose the compacted depth required by the project. Multiplying these three dimensions gives volume. The calculator converts mixed display units into a consistent internal unit before calculating cubic yards, cubic feet, or cubic meters.
Weight is an estimate because gravel density changes with stone type, grading, moisture, and how tightly the material settles. Supplier quotes are often sold by the ton, while landscape plans are measured by volume, so both results are useful.
Depth, compaction, and waste allowance
A one-inch error in depth across a large driveway can change the order significantly. Measure several points and prepare the base before deciding the average depth. If the supplier publishes a compaction factor for the chosen aggregate, use it rather than relying on a generic percentage.
Waste allowance covers minor variations and material lost during transport or spreading. It should not replace accurate measurements. Irregular shapes are best divided into rectangles, calculated separately, and added together.
How to use this gravel calculator
- Choose the shape and enter the project dimensions.
- Set the compacted gravel depth and supplier density.
- Add a practical extra allowance, then use the order volume or weight preferred by your supplier.
Formula and method
Bulk density varies by stone type, grading, moisture, and compaction. The default is an estimate, not a supplier specification.
Driveway gravel example
A 30-foot by 12-foot area at a compacted depth of 4 inches has a volume of 120 cubic feet: 30 × 12 × 4/12. Dividing by 27 gives about 4.44 cubic yards before waste or compaction adjustments.
With a 10 percent allowance, the order becomes about 4.89 cubic yards. Convert that volume to tons using the supplier's density for the exact stone, then round according to the supplier's delivery increments.
Common mistakes to avoid
- Entering inches of depth as though they were feet.
- Using loose-delivery depth when the design specifies compacted depth.
- Applying a generic density to specialty stone without checking the supplier.
- Rounding every small section before adding an irregular area.
Accuracy and practical limits
Volume is mathematically exact for a rectangular area and the dimensions entered. Weight remains an estimate. Ground variation, compaction, moisture, aggregate size, and truck-load increments should be confirmed with the material supplier.
Method basis: Standard mathematical definitions and the assumptions stated above. See our editorial and testing standards.
Frequently asked questions
Should I order by volume or weight?
Use the unit quoted by your supplier. The tool shows both but the weight depends on the density you enter.
Why add extra gravel?
Excavation variation, compaction, and uneven subgrade can require more than the geometric volume.
Does cost include delivery?
No. The cost field multiplies estimated US tons by material price only.