How Many Tons of Rock Do I Need? A Contractor's Calculator
By Seth Cvancara, Founder, Mouse Mining LLC. Updated .
To figure tons of rock, multiply length by width by depth in feet, divide by 27 for cubic yards, then multiply by the material's weight per cubic yard. For most crushed rock that is roughly 1.4 to 1.5 tons per yard. Mouse Mining confirms the exact factor for your material on the quote.
Getting tonnage right keeps you from paying for a partial extra load or running short mid pour. This post is part of our complete guide to ordering bulk rock and aggregate.
What is the formula for tons of rock?
Tons equals length in feet times width in feet times depth in feet, divided by 27, times tons per cubic yard. Convert depth from inches to feet first by dividing by 12. The division by 27 turns cubic feet into cubic yards, the unit weight factors are published in.
- 1
Measure the area
Length times width in feet gives square feet.
- 2
Convert depth to feet
Divide the depth in inches by 12. Four inches is 0.33 feet.
- 3
Get cubic yards
Square feet times depth in feet, divided by 27.
- 4
Convert to tons
Cubic yards times the material's tons per cubic yard.
- 5
Round to truckloads
Material ships in full truckloads with a 25 ton minimum, so round up to what the job actually needs.
How many tons for a 100 by 20 foot driveway?
A 100 by 20 foot area at 4 inches deep is 2,000 square feet times 0.33 feet, or about 667 cubic feet. Divided by 27 that is about 24.7 cubic yards. At 1.4 tons per yard, plan on roughly 35 tons. At 6 inches deep it is roughly 52 tons.
| Depth | Cubic yards | Approximate tons |
|---|---|---|
| 2 inches | 6.2 | 8.6 |
| 3 inches | 9.3 | 13.0 |
| 4 inches | 12.3 | 17.3 |
| 6 inches | 18.5 | 25.9 |
| 8 inches | 24.7 | 34.6 |
| 12 inches | 37.0 | 51.9 |
These figures use a 1.4 tons per yard example factor. Actual weight depends on the material, its gradation and moisture, so treat the table as an estimate and confirm on your quote.
Should I order extra for compaction?
Compactable products like road base lose volume when rolled, so the loose tons you order must cover the compacted depth on the plans. How much extra depends on the material and your compaction effort. Tell us the finished compacted depth and we will factor it into the tonnage on the quote.
Not sure which base product fits? Compare Class 6 road base vs pit run vs structure fill.
What if my job is smaller than 25 tons?
Mouse Mining sells full truckloads with a 25 ton minimum, built for contractors, landscape companies and supply yards. If your calculation lands under that, the job is usually better served by a local retail yard. For multi phase jobs, combine phases into full loads.
Once you have your number, get a delivered quote for your tonnage or read what a delivered price includes.
Need a delivered price?
Send the material, tonnage and delivery location. 25 ton minimum. Delivering across Colorado, Wyoming, New Mexico, Utah, Arizona and Texas.
Frequently asked questions
How many cubic feet are in a cubic yard?
27. A cubic yard is 3 feet by 3 feet by 3 feet.
How much does a cubic yard of gravel weigh?
Most crushed rock and gravel weighs roughly 1.4 to 1.5 tons per cubic yard. The exact figure depends on the material, so confirm it on your quote.
Am I billed on the estimate or the delivered tons?
On the tons actually delivered, from the scale tickets, at the per ton price on your quote.
Can Mouse Mining calculate tonnage from my plans?
Yes. Send the plan sheet or the area, depth and spec, and we will work the tonnage into the quote.
What is the minimum order?
Full truckloads, 25 ton minimum.