Quick answer
Multiply area by installed depth in feet to get cubic feet, then divide by the exact volume printed on one bag and round up.
Step by step
- Measure the area. Split irregular beds into simple shapes.
- Choose depth. Use project-specific aggregate guidance.
- Calculate volume. Area × depth in feet.
- Convert to bags. Divide by the bag's cubic-foot volume.
Formula or rule of thumb
bags = ceil((area × depth) ÷ bag volume)
Example
A 100 ft² bed at 2 in depth equals 16.7 ft³. With 0.5 ft³ per bag, plan for 34 bags before site allowance.
Common mistakes
Do not estimate bags from weight alone; bag volume and aggregate density vary.
Planning note: product yields, installation methods, site conditions and local requirements can change the final quantity. Use the exact manufacturer or supplier information before purchasing.
FAQ
Is gravel sold by weight or volume?
Bulk gravel is commonly sold by weight or cubic yard, while retail bags show volume or weight.
Does depth include a base?
Measure and calculate the installed gravel layer separately from any base course.
Can I use this for decorative stone?
Yes for geometric volume, but product density and bag size still vary.