Most people call us with the same question: “How many yards of gravel do I need?” It’s the right thing to ask before you order. Nobody wants to pay for a load and a half when one would have done it, and nobody wants to run short halfway across the pad and wait on a second truck.

Here’s the honest version of the math, and then the part that trips people up.

Start with length, width, and depth

Gravel is sold by weight (Ton), but we will do the conversion for you. To get cubic yards, you multiply length by width by depth, all in feet, and divide by 27. There are 27 cubic feet in a yard, so that last step is what turns your measurements into an order.

The piece people miss is depth, because you measure it in inches and have to convert it to feet first. Four inches is 0.33 feet. Six inches is 0.5 feet.

So a driveway 100 feet long and 12 feet wide, laid 4 inches deep, is 100 × 12 × 0.33 ÷ 27, right around 15 cubic yards. Write that formula down and you can rough out any driveway, pad, or trench backfill on the back of an envelope.

Where the estimate goes sideways

Two things pull the real number away from the envelope math.

First, gravel compacts. What comes off the truck loose settles once it’s spread and rolled, so you order a little more than the raw calculation to end up with a solid section at the depth you wanted. How much more depends on the rock and how deep you’re going, a base course behaves differently than a thin top layer.

Second, “how much” depends on what you’re building on. A soft, wet spot down in Kelso’s river-bottom soil needs a deeper, stronger section than a firm pad up on the volcanic ground around Castle Rock. Same footprint, different amount of rock. Local ground is the one variable the online calculators can’t see, and it’s usually the one that decides your number.

The material matters too. Pit run going down as a base is a different order than crushed 5/8-minus finishing the surface. Get the wrong rock for the job and it doesn’t matter how carefully you did the yardage, the driveway won’t hold up the way you wanted.

The better way to think about it

Measure your length and width, pick a working depth, run it through the formula, and you’ll know whether you’re looking at a few yards or a few truckloads. That’s enough to plan around.

Then let us check it against the ground you actually have and the material that belongs on it. We haul our own rock, so the same crew that helps you figure the yardage is the one that brings it to the site, no middleman guessing at your driveway from an office across the county.

Ready to get a real number for your project? Call us at (360) 957-8847.

How Much Gravel Do You Actually Need? Figuring Yardage Before You Order

Start with length, width, and depth

Where the estimate goes sideways

The better way to think about it