📚 What's in This Guide
Figuring out how much dirt to order for a grading job, a raised bed, or a backyard low spot usually turns into guesswork. The delivery truck shows up short, or with two yards too many.
This dirt calculator solves that by turning your project's length, width, and depth, or diameter for round areas, into the numbers that actually matter: cubic yards, tons, and how many truckloads you will need. Enter up to four separate areas, rectangular, circular, or a mix of both, pick the material you are working with, and the calculator above handles the rest, including an ordering allowance so the number you order matches what you actually need on the ground.
1. How the Dirt Calculator Works
The calculator starts with the footprint of each area you are filling: length and width for a rectangle, or diameter for a circle, plus how deep you need the fill to be. It converts your depth from inches to feet, multiplies it by the footprint, and gets a raw volume in cubic feet.
It then adds an ordering allowance, since loose dirt settles once it is spread and tamped. This allowance is a planning buffer, not a precise engineering compaction calculation. That adjusted volume becomes cubic yards, the unit most suppliers sell by, and then tons using the density of the material you select.
If your project spans several areas, say a low spot in the backyard plus a circular tree well, add each one as its own row. The calculator totals them automatically instead of making you add up several results by hand.
Each area is treated as a simple rectangle or circle. Irregular shapes should be split into a few of these simpler shapes and entered as separate rows. Density and compaction figures are typical starting points, not guaranteed values for your exact material.
2. How to Use the Dirt Calculator
- Choose a shape for your first area, Rectangle or Circle.
- Enter the length and width in feet, or the diameter in feet for a circle.
- Enter the fill depth in inches.
- Select your material, or enter a custom density if your supplier has given you one.
- Adjust the ordering allowance if you want a different buffer than the 15% default.
- Add another area if your project has more than one section.
- Optionally enter a price per cubic yard or per ton to see an estimated cost.
3. Dirt Calculator Formula
Rectangle volume (cu ft) = Length x Width x (Depth in inches / 12)
Circle volume (cu ft) = Pi x (Diameter / 2)² x (Depth in inches / 12)
Length and Width are the footprint of a rectangular area in feet, Diameter is the distance across a circular area in feet, and Depth is the fill thickness in inches.
Once every area's raw volume is added together, the ordering allowance and unit conversions bring it to an order-ready number:
Total loose volume = Sum of all area volumes x (1 + ordering allowance %)
Cubic yards = Total loose volume (cu ft) / 27
Tons = Cubic yards x density (lb per cu yd) / 2,000
4. Worked Example
Using the calculator's defaults: a 20 by 15 ft rectangle at 4 inches deep, plus a 6 ft diameter circle at 6 inches deep.
| Area | Footprint | Volume |
|---|---|---|
| Rectangle, 20 x 15 ft, 4 in deep | 300 sq ft | 100 cu ft |
| Circle, 6 ft diameter, 6 in deep | about 28.27 sq ft | about 14.14 cu ft |
Combined raw volume = 100 + 14.14 = 114.14 cubic feet. Add a 15% ordering allowance: 114.14 x 1.15 = about 131.26 cubic feet.
Convert to cubic yards: 131.26 / 27 = about 4.86 cubic yards, which most suppliers round up to 5 for delivery. At Fill Dirt's default density of 2,410 lb per cubic yard, that is about 5.9 tons, or 1 truckload at 10 cubic yards per load. At $45 per cubic yard, that comes to roughly $219.
5. Understanding Your Result
The cubic yard figure is your primary ordering number, since it is what most suppliers quote and deliver by. The tons figure matters when a supplier bills by weight, or when you need to know what a delivery vehicle can carry.
Both are estimates, not exact measurements. Real soil and fill dirt density varies with moisture content, particle size, and how much organic matter or rock is mixed in, so two loads described as fill dirt from different suppliers can weigh noticeably different amounts for the same volume. According to USDA NRCS guidance on soil bulk density, natural soil density commonly falls between roughly 1.0 and 1.4 grams per cubic centimeter, and can run higher once compacted. That variability is part of why this calculator lets you pick a material or enter a custom density instead of relying on one fixed number.
Treat the result as a strong planning number, and confirm the exact density with your supplier before finalizing a large order. When in doubt, round up slightly rather than down. A small surplus of dirt costs far less than a second delivery.
6. Units and Conversions
- 1 cubic yard equals 27 cubic feet (3 ft x 3 ft x 3 ft). This is the conversion the calculator relies on most.
- 1 cubic yard of fill dirt is roughly 1.0 to 1.35 tons, depending on moisture and compaction. The calculator defaults to about 1.2 tons per cubic yard for Fill Dirt.
- Depth is almost always measured in inches, while footprint is measured in feet. Mixing these up is the single most common calculation mistake for this kind of project.
7. Practical Tips
- Measure depth as the actual thickness of fill you need, not the total depth of the hole or bed if part of it is already filled.
- Keep footprint in feet and depth in inches, and let the calculator handle the conversion.
- Add 10 to 15% for a small project, and closer to 20 to 30% for a large grading job.
- Ask your supplier whether their price is per cubic yard or per ton, and use the matching output.
- For odd shapes, split the space into a few rectangles and circles rather than averaging one set of dimensions.
8. Common Mistakes
- Mixing units: entering depth in feet instead of inches can throw off the entire result by a factor of 12.
- Confusing square measurements with cubic ones: square footage tells you nothing about volume until it is multiplied by depth.
- Skipping the ordering allowance: ordering exactly the calculated volume often leads to falling short once the material settles.
- Assuming all dirt has the same density: topsoil, fill dirt, and compacted fill genuinely weigh different amounts per cubic yard.
- Rounding too early: round only the final cubic yard or ton figure, not the inputs along the way.
9. Related Calculations and Use Cases
Dirt and fill calculations often overlap with other landscaping work. If your project also involves finishing the surface with decorative stone or edging, our River Rock Calculator can estimate that material using the same length, width, and depth approach.
Common real-world use cases include filling a low spot before reseeding a lawn, backfilling around a new foundation, building up a raised garden bed, leveling a yard before laying sod, and filling in a decommissioned pool excavation.
10. Frequently Asked Questions
Multiply the length and width of your area in feet to get the square footage, multiply that by your fill depth converted to feet, then divide by 27 to convert cubic feet into cubic yards. The calculator above does this automatically and lets you total multiple areas at once.
It depends on the material and its moisture content, but a commonly used planning figure for fill dirt is roughly 1.2 tons per cubic yard, about 2,400 pounds. Topsoil tends to be lighter when loose, while compacted fill is heavier. Soil density genuinely varies with moisture, particle size, and organic content, so treat any single figure as a planning estimate and confirm the exact number with your supplier for large orders.
Topsoil is the nutrient-rich surface layer meant for planting. It contains more organic matter and is screened for growing plants. Fill dirt is subsoil with little to no organic matter, used to raise grade, fill holes, or backfill, and it is denser and cheaper than topsoil. Select fill is a further engineered version of fill dirt, screened and graded for structural or drainage-sensitive uses like foundation backfill.
A common range is 10 to 15 percent extra for smaller projects and up to 20 to 30 percent for larger grading jobs, since loose delivered dirt settles once it is spread and compacted. This is a planning buffer, not a precise engineering compaction calculation, so the exact amount still depends on your soil type and compaction method, and the calculator's allowance field is adjustable rather than fixed.
It depends on the truck. A standard full-size dump truck commonly carries around 10 cubic yards per load, while a smaller pickup truck load is closer to 2 to 3 cubic yards. The calculator's truck capacity field defaults to 10 cubic yards but can be adjusted to match your vehicle or supplier's load size.
This calculator is for planning purposes only. Confirm exact density, ordering allowance, and pricing with your supplier before ordering.