Concrete CalcKit

Fill Dirt Calculator

Find how much fill dirt you need to raise grade, backfill a hole or level a low spot. Enter the area and depth to get cubic yards and tons, with a compaction allowance.

Fill dirt needed

Fill dirt needed
0.00
cubic yards
Weight
0.00
US tons (approx)

Assumes ~1.2 tons per cubic yard. Compaction allowance covers settling once the fill is tamped.

How to calculate fill dirt

Fill dirt is estimated by volume, the same way as topsoil or gravel: area in square feet multiplied by depth in feet (depth in inches ÷ 12), divided by 27 for cubic yards. The formula is cubic yards = area (ft²) × depth (in) ÷ 12 ÷ 27. Fill dirt is typically sold and delivered by weight, and because it is usually a sandy or clay subsoil with little organic matter, it runs a bit denser than topsoil at roughly 1.2 US tons per cubic yard.

Fill dirt vs topsoil

Fill dirt is bulk subsoil used to raise low areas, backfill around a foundation, fill in an old pool or pond, or build up grade before a structure goes in. It is not intended to support plant growth and is usually cheaper than topsoil. Topsoil is the nutrient-rich, organic-heavy surface layer meant for lawns and planting. A common approach is to bring a site up to rough grade with fill dirt, then cap it with 4 to 6 inches of the topsoil calculator's output before seeding or planting.

Compaction changes the math

Loose fill dirt settles noticeably once it is spread, watered and compacted, more so than most other materials on this site. For anything structural, a shed pad, a driveway base or fill that will carry a building, place it in 6 to 8 inch lifts and compact each lift before adding the next, rather than dumping the full depth at once and compacting only the top. Budget 10 to 15 percent extra volume to account for this settling, more for deep fills or looser native soil.

When fill dirt isn't the right material

If the project needs load-bearing stability under a slab, driveway or patio, compacted gravel or crushed stone is usually the better choice over plain fill dirt, since it compacts to a denser, more predictable base and drains better. Use fill dirt for bulk grading and low spots, and the gravel calculator or crushed stone calculator for the structural base layer itself.

Frequently Asked Questions

How many tons of fill dirt are in a cubic yard?
Fill dirt weighs roughly 1.2 US tons per cubic yard (about 2,400 lb), denser than screened topsoil because it has little organic matter and is often a sandy or clay-based subsoil. The calculator uses 1.2 tons per cubic yard by default.
What is the difference between fill dirt and topsoil?
Fill dirt is subsoil used to raise grade, fill holes or build up a base; it is not meant to grow plants in and is cheaper than topsoil. Topsoil is the nutrient-rich surface layer used for planting and lawns. If you are filling a hole and then planting over it, use fill dirt for the bulk and a layer of topsoil on top.
Should I compact fill dirt?
Yes, for anything structural like a building pad, driveway base or area that will carry weight. Fill dirt should be placed and compacted in lifts of about 6 to 8 inches rather than dumped in one deep layer, or it will settle unevenly over time. For a simple low-spot fill under lawn, light compaction is usually enough.
How much extra fill dirt should I order?
Order 10 to 15 percent more than the calculated volume. Fill dirt compacts and settles more than it appears when loose, so the finished, compacted depth ends up a bit less than the volume delivered.

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