Top Soil Calculator
Topsoil yardage by area and depth — bags or bulk
What is top soil calculator?
A top soil calculator gets you to the same answer as the homeowner’s first instinct on any sod, lawn, or grading project: how many cubic yards or bags of screened soil do I need. The volume math is the same as any other bulk material — area times depth — but bag sizes for top soil vary, and the bulk-vs-bagged break-even matters more than for most landscape products because top soil is heavy.
The default density is 80 lb/ft³, which is typical for moderately moist screened top soil. Heavy clay-rich soil runs 100-110 lb/ft³ and weighs 25-35% more per yard; light sandy soil falls to 65-70 lb/ft³. Volume math is identical regardless; only the tonnage readout shifts.
What depth to use? For sod prep over rough grade, 4 inches works on well-drained sub-soil and 6 inches is the textbook standard over compacted clay. For tree wells, plan 6-8 inches around the root ball — but never bury the root flare. For patching low spots, 1-2 inches mixed into the existing turf is plenty; thicker layers smother the grass below.
Bulk vs bagged: at the home center, top soil bags come in 0.75, 1, or 1.5 cu ft sizes at $4-8 each. A cubic yard is 27 of the 1-cu-ft bags. Past about 50 bags (~2 yd³), bulk delivery from a landscape supply yard typically wins on price ($25-45/yard) and saves the lifting. Bag-grade top soil is also often cleaner than bulk, so for small projects where you only need a few bags, the convenience can be worth the premium.
The 10% waste factor default covers spillage during transfer (top soil is messy) and minor settling. For tree wells, raised beds, and any deep fill, bump to 20% — fresh-laid top soil settles 10-15% in the first month of watering, and you’ll want extra to top off before sod or seeding takes hold.
When to use a top soil calculator
- Sod prep over rough grade — Lay 4 inches of screened top soil before unrolling sod. The calculator handles a single uniform depth for the whole yard.
- Filling tree wells — A 6 ft diameter tree well at 8 inches deep takes more soil than expected. Use the round-area inputs and the calculator does the math.
- Patching low spots in the lawn — Multiple small low spots add up to surprising volume. Estimate average area and average depth across all spots.
How to use the Top Soil Calculator
- Measure the area — For sod prep and rectangular beds, length times width. For tree wells and round patches, the calculator takes diameter directly. For irregular grading, break into rectangles and add.
- Pick a depth — 4 inches for sod prep over rough grade. 6 inches over compacted clay sub-soil. 8 inches in tree wells. 1-2 inches for patching shallow lawn divots.
- Read the bag count — Output shows bags of the size you select. 1-cu-ft is the retail standard; 0.75 and 1.5 are also common. Round up — partial bags don't store outdoors.
- Apply waste factor — 10% covers spillage during transfer and minor settling. Bump to 15-20% if you're filling deep tree wells or raised structures where soil settles significantly the first month.
Worked examples
Sod prep, 30 ft x 40 ft at 4 in
Input: 30 ft x 40 ft x 4 in depth
Output: 14.8 cu yd / 400 of 1-cu-ft bags (with 10% waste)Tree well, 6 ft diameter at 8 in
Input: Circle 6 ft diameter x 8 in depth
Output: 0.78 cu yd / 21 of 1-cu-ft bagsSlope the soil away from the trunk slightly to keep the root flare exposed.
Lawn patches, total 100 ft^2 at 2 in
Input: 10 ft x 10 ft x 2 in depth
Output: 0.62 cu yd / 17 of 1-cu-ft bags