Dirt Calculator
Cubic yards of fill or grade dirt by area and depth
What is dirt calculator?
A dirt calculator answers the homeowner’s first question on any grade or backfill project: how many cubic yards of dirt do I need delivered. The volume math is straightforward — area times depth — but compaction and the difference between dirt, fill dirt, and topsoil all change the practical order quantity.
The default density is 80 lb/ft³, which is typical for moderately screened dirt at a normal moisture content. Heavier clay-rich fill or wet earth runs 100-110 lb/ft³ and weighs proportionally more per yard; the volume calculation doesn’t change, only the tonnage readout.
What depth to use? There is no single standard — the right depth is whatever fill it takes to reach final grade. For yard low spots, 2-4 inches of fill is typical. For shed pads, 4-6 inches of compacted base. For foundation backfill, the depth equals the trench depth, and you should plan for compaction in 4-6 inch lifts.
Bulk vs bagged: dirt is bulk-only on any real job. Bagged “fill dirt” exists at home centers but costs many times more per yard than bulk delivery. For anything bigger than a wheelbarrow load, call a landscape or excavation yard for a half-yard or full-yard truck delivery.
The 10% waste factor default covers spread loss and minor over-fill at the edges of the project. For backfill or grade work where the fill must be compacted, bump to 20-25% — loose-dumped dirt settles roughly 15-25% under its own weight or with mechanical compaction. Order on the high side; leftover fill is easy to spread, but a return trip to the supplier eats half a Saturday.
When to use a dirt calculator
- Foundation backfill — Filling around a new footing or wall takes more dirt than the void appears to need. Enter trench dimensions and depth to get a delivery quantity.
- Shed pad and grade fix — Leveling a sloped patch for a 10 ft x 12 ft shed pad. Pick the average fill depth across the slope and the calculator handles the volume.
- Raising a low spot — Yard low spots that puddle after rain need 2-4 inches of compacted fill. The calculator outputs yards before compaction allowance.
How to use the Dirt Calculator
- Measure the area — Foundation trenches, shed pads, and low spots are usually rectangular — multiply length by width. For an irregular slope, use the average fill depth times the area.
- Pick a depth — There's no standard depth — use whatever fill is needed to reach final grade. For low-spot fill that compacts and settles, plan for 25% more than the visual void.
- Read the volume — Bulk dirt is sold by the cubic yard at most landscape and excavation suppliers. Output shows yards directly; the tonnage is for trucking or weight-load reference.
- Apply waste factor — 10% covers spread loss and minor over-fill. Bump to 20-25% for projects where the fill must be compacted in lifts — compaction losses are real.
Worked examples
Backfill trench, 30 ft long
Input: 1.5 ft x 30 ft x 4 ft depth
Output: 6.7 cu yd / 10.7 tons (with 10% waste)10 ft x 12 ft shed pad, 6 in average fill
Input: 10 ft x 12 ft x 6 in depth
Output: 2.44 cu yd / 3.92 tonsCompact in 4-in lifts and over-order by 25% if you need a final grade match.
Lawn low-spot fill
Input: 8 ft x 8 ft x 3 in depth
Output: 0.65 cu yd / 1.05 tons