Ordering fill dirt by guesswork is a good way to end up with a pile left over, or a pad that comes up short halfway through. A little math up front saves you a second trip.
We're Josh and Mark Collier with Middle TN Grading & Clearing. We haul fill dirt, gravel and stone straight from the quarry and spread and compact it on site. We don't sell material. Here's how to figure what you need.
The Fill Dirt Calculator: Cubic Yards
Fill is measured in cubic yards. The formula is:
Cubic yards = length (ft) × width (ft) × depth (ft) ÷ 27
There are 27 cubic feet in a cubic yard, which is where the 27 comes from.
If your depth is in inches, divide it by 12 first to get feet. Six inches is 0.5 ft. Four inches is about 0.33 ft.
Worked Example: Raising a House Pad
Say you want to raise a pad area 40 feet long and 30 feet wide by 1 foot.
- Length × width: 40 × 30 = 1,200 square feet
- Times depth: 1,200 × 1 = 1,200 cubic feet
- Divide by 27: 1,200 ÷ 27 ≈ 44.4 cubic yards
That 44.4 is the amount of packed, finished fill the pad needs.
Worked Example: Filling a Low Spot
A low spot 20 ft by 15 ft, about 6 inches deep:
- 6 inches ÷ 12 = 0.5 ft
- 20 × 15 × 0.5 = 150 cubic feet
- 150 ÷ 27 ≈ 5.6 cubic yards
For an odd shape, break it into rectangles, figure each one and add them up.
Allow Extra for Compaction
Here's where people come up short. Dirt shows up loose and fluffy. When it gets packed down, it shrinks. So you need more loose fill than your finished number.
According to concretecalculate.com and American Rock Supply, fill shrinks roughly 10–25% when compacted: about 10–15% for granular material and 20–25% for clay. The Federal Highway Administration's earthwork design guidance explains the same shrink-and-swell idea that road builders plan around.
In practice, that means multiplying your compacted number by about 1.15 for mixed fill, or 1.20 to 1.25 for clay.
Back to the pad: 44.4 cubic yards × 1.2 ≈ 53 cubic yards loose.
That's a planning number, not a promise. Moisture and the exact material change it.
Converting Yards to Tons
Some places measure by the ton. According to concretecalculate.com and American Rock Supply, fill dirt weighs about 1.1 to 1.35 tons per loose cubic yard, depending mostly on how wet it is.
So 53 loose yards might be roughly 58 to 72 tons. Wet clay sits at the heavy end.
How Many Truckloads?
That depends on the truck. Dump trucks come in different sizes, and how much one carries depends on the truck and the material. Don't assume a "load" is a set number of yards. Ask whoever is hauling it how many yards or tons their truck carries, then divide.
Picking the Right Fill
- Fill dirt or clay fill is for building up grade, pads and low spots. In Middle Tennessee, a lot of what's under us is clay. It makes a solid base when it's compacted in thin layers (lifts), not dumped and left.
- Topsoil is for growing grass and gardens. It's not for building pads. It holds organic matter that breaks down and settles.
- Gravel and stone are for driveways, drainage and bases.
A good setup is usually compacted fill for structure, with a few inches of topsoil on top where you want grass.
Do You Need a Permit to Bring in Fill?
Sometimes. In Tennessee, TDEC's Construction General Permit covers clearing, grading, filling and excavating that disturbs 1 acre or more (or less, if part of a larger development). Inside the City of Franklin, the City's permits page says projects disturbing 5,000 square feet or more need a Stormwater & Grading Permit. Other towns have their own rules, so check with your city or county before you start.
Frequently Asked Questions
How do I calculate how much fill dirt I need? Length × width × depth in feet, divided by 27. Then add about 15–25% for compaction.
How many tons are in a yard of fill dirt? About 1.1 to 1.35 tons per loose cubic yard, according to concretecalculate.com, depending on moisture.
Fill dirt or topsoil, which do I need? Fill for building up and pads. Topsoil only for the top few inches where you want things to grow.
How much extra fill should I order for compaction? Roughly 15% extra for mixed fill and 20–25% for clay, based on the shrink ranges above.
Let Us Haul It and Pack It
You can see how we handle hauling on our fill dirt and gravel hauling page.
If you'd rather have someone check your numbers, call Josh or Mark at (931) 458-1500. We'll come take a look on site, measure it up, haul from the quarry and spread and compact it right.