How Much Fill Dirt Do I Need? A Simple Guide Plus Delivery
Fill dirt is one of those things people either order way too much of or, worse, not enough of. Too much and you are paying to haul material you did not need and then paying again to spread it somewhere. Too little and the trucks have to come back, the job stalls, and the second trip always seems to land on the day it rains. The good news is that figuring fill is fourth grade math with one trap in it, and once you know the trap you can get your number close enough to order with confidence.
The math
Fill dirt sells by the cubic yard, and a cubic yard is just a box three feet on every side. To figure how many you need, measure the area you are filling in feet, multiply length x width x depth, and divide by 27. That is it. Length x width x depth gives you cubic feet, and 27 cubic feet make one cubic yard.
The trap is that dirt does not stay the size it arrives at. When fill comes off the truck it is loose and fluffed up. Once it gets spread, wheel rolled, and compacted, it packs down smaller than the pile it started as. If you order exactly what the math says, you will come up short every time. Add 10 to 20 percent to your number for compaction and settling. Use the low end if the fill is just dressing up a yard, and the high end if it is going under anything structural or getting compacted in lifts.
A worked example
Say you are building up a pad that is 54 feet long by 50 feet wide, and you need to raise it one foot.
54 x 50 x 1 = 2,700 cubic feet.
2,700 divided by 27 = 100 cubic yards.
Add 15 percent for compaction and you land at 115 yards. Round to 120 and you have a little cushion for the low spot you did not notice until the trucks showed up. That is your order.
If your depth is in inches instead of feet, convert it first. Six inches is 0.5 feet, four inches is about 0.33. A common mistake is multiplying by the inch number and wondering why the answer says you need a mountain.
What a dump truck actually holds
Once you know your yardage, you can figure your truck count. A tandem dump truck typically hauls around 12 yards, and a tri axle runs closer to 16 to 18. So that 120 yard pad above is roughly 7 to 10 truckloads depending on what shows up. A single axle dump or a big dump trailer might carry 5 or 6 yards. A pickup is a different story. A yard of fill weighs better than a ton, so even a full size truck is realistically a one yard truck when the material is dirt. The payload rating runs out long before the bed looks full, and that is why our loader operator stops where he stops.
Knowing the load count matters for more than the bill. Ten loads of fill means ten trucks crossing your yard, your culvert, and maybe your neighbor's patience. If access is tight or the ground is soft, which it often is on the low lots close to the bays and bayous, tell whoever is hauling before the first truck arrives instead of after it sinks.
How deep does a building pad run
On the jobs we build around here, house and garage pads usually come up somewhere between one and three feet above the surrounding grade. The dirt does not go in as one big push either. It goes down in layers that each get rolled tight before the next one lands on top, which matters to your order because a compacted layer takes up less room than the loose dirt that came off the truck. That is the same trap from the math above, showing up again at the pad.
How high your pad needs to sit is a different question, and it is not one to guess at or take off a blog post. Your lot and your builder set that number, and it changes from parcel to parcel, so get it confirmed before anybody orders dirt. For rough planning only, figure somewhere in that one to three foot range over the footprint of the slab, plus a few feet of apron past the edges so the pad can slope down instead of dropping off, and you are in the neighborhood. We have built a lot of pads around here and we can tell you what usually comes up on ground like yours.
Why our sand behaves differently than clay
Most fill in this part of Northwest Florida is sandy, and that is a good thing. Down along the water in Navarre, Gulf Breeze, and Destin you are usually working in sugar sand. It drains fast, spreads easy, and compacts predictably with normal equipment. It does not hold water and swell the way clay does, and it does not turn into a slick mess after one of our summer storms. The tradeoff is that clean sand does not lock together like clay, so it wants confinement and proper compaction in lifts rather than one big dump and a prayer. If you have ever built a sandcastle above the wet line at the beach, you already understand the principle. Head north and inland toward Pace, Milton, Crestview, and DeFuniak Springs and the digging changes on you. Clay packs tighter but only in a narrow moisture window, and getting it wrong means a pad that pumps and rolls under load. Out toward the Yellow River basin you can hit both in the same afternoon. For most jobs near the water, good sandy fill placed and compacted right is exactly what you want under a slab.
When to let the contractor figure it
The math above works great on a flat, defined area. It gets shaky when the ground is not flat, which is most of the time. Filling a sloped lot, bringing a low corner up to meet grade, or building a pad to a surveyed elevation means averaging depths across the whole site, and eyeballing that is how people end up 40 yards short. If somebody has handed you a finished floor number, or you have a drainage plan, or the lot has any real fall to it, have us figure it. We shoot the grades, run the numbers, and stand behind the count. That is a lot cheaper than guessing at it twice.
Either way, the dirt itself is easy. We own our own fill dirt pit at 3125 River Rd in Navarre, so you can buy fill by the cubic yard, bring your own truck or trailer and we will load it, or have us deliver it to your site anywhere in the area. We keep pricing simple too, just call and ask.
NOBL Sitework is a licensed general contractor (CGC1537340) serving Santa Rosa, Okaloosa, Walton, Escambia, and Bay counties, with our own dirt pit in Navarre. If you want help with your yardage or want fill delivered, call us at 850-238-3307.
