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Topsoil vs Garden Soil vs Potting Mix

Which bag or bulk pile belongs in a lawn, a raised bed, and a container — and why potting mix is a bad way to fill a 4×8.

Updated August 25, 2026

Three products, three jobs

Topsoil is mineral soil from the ground, ideally screened. Garden soil is a marketing name for a blend, usually topsoil plus compost and sometimes sand or bark. Potting mix is not soil. It is a container medium, often peat or coconut fiber with perlite, made to drain in a pot.

If you fill a raised bed with potting mix, you will spend a surprising amount of money and the bed will settle as the organics shrink. If you fill a pot with screened topsoil, the pot will stay wet and heavy and the plant will sulk.

ProductBest placeAvoid
Screened topsoilLawns, final grade, mixing into bedsClosed containers
Garden / raised-bed blendIn-ground beds, raised boxesUsing it as cheap fill
Potting mixPots, window boxes, seed startingFilling a 4×8 by the bag
CompostAmending any of the aboveA 100% compost “soil” cap on a lawn

A practical mix for a vegetable box

Minnesota Extension’s raised-bed mix is about ½–⅔ topsoil with ⅓–½ plant-based compost. The raised-bed guide on this site sizes the box; this page is about what goes in it. If you only have bagged garden soil, that can work for one 4×8 (Penn State York: a common frame is 4 × 8 × 1 ft). Read the bag for volume, not for the word “organic” in 90-point type.

For a lawn, skip the garden blend. You want screened topsoil that will firm up. A bark-heavy garden soil stays spongy and sod will not root evenly.

Cost per yard of the bagged story

Illustrative bag-aisle math, not a survey: potting mix at $10 per 2-cubic-foot bag is about $135 per cubic yard. Garden soil bags are often a little cheaper and still far above Angi/Lawn Love bulk screened bands (this site’s $15–25 per yard overlap). Use bags for containers and for the last amendment. Use bulk for anything you measure in yards.

The calculator’s bag count is there so you can see the absurdity in numbers: a 4×8 at 12 inches is 1.2 yards, 17 of the 2-cubic-foot bags. That is a reasonable bag job if the mix is right. The same depth on a 500 square-foot lawn is 84 bags. That is not a bag job.

How to read a bulk “garden mix”

Ask what is in it. A good answer names the soil source and the compost source. A bad answer is “it’s the black stuff.” Look for weed tubers, trash, and a sour smell. Fresh uncomposted organics will heat and then shrink after you plant.

Containers, again, because the aisle is confusing

A 15-gallon pot wants potting mix. The volume of a pot is not “length × width × depth ÷ 324” unless you treat it as a cylinder or a box on purpose. For a true cylinder, use the circle tool with the pot’s inside diameter and the fill depth. Most people are better off buying potting mix by the bag until the containers are full and using this site for ground-level work.

If you try to cheap out by putting screened topsoil in the bottom third of a large pot and mix on top, you create a perched water table. The pot stays wet at the interface. Use one medium.

Sources

Numbers on this page are planning figures. Follow the link for the original table or standard. Full list: Sources.

  1. NIST. Handbook 44, Appendix C — General Tables of Units of Measurement. 1 cubic yard = 27 cubic feet. Coverage identity: 27 × 12 = 324 sq ft at 1 inch.
  2. Penn State Extension. Lawn Establishment. Minimum 4–6 inches (firmed) of quality topsoil to establish turf; blend into subsoil.
  3. University of Illinois Extension. Preparing Lawn Soil and Site. Aim for six inches or more of well-prepared soil before seed or sod.
  4. University of Nebraska–Lincoln Extension. Establishing Lawns From Sod. Replace topsoil to a minimum of about 4 inches after rough grade; sod often cut 0.25–0.5 in thick.
  5. University of Arkansas System Division of Agriculture. Establishing a Lawn From Sod (FSA-2042). About 19 cubic yards of topsoil make a 6-inch layer over 1,000 sq ft; sample the upper 4–6 inches.
  6. Angi. What Is the Cost of Topsoil? [2026 Data]. National homeowner bands: about $10–$55/yd³ by type; screened loam $18–$26; delivery often $50–$150/trip.
  7. Lawn Love. How Much Does Topsoil Cost in 2026?. Bulk topsoil commonly cited at about $10–$50 per cubic yard, plus delivery.
  8. University of Minnesota Extension. Raised bed gardens. Mounded beds often 6–8 in high. Mix about ½–⅔ topsoil with ⅓–½ plant-based compost. Deeper (1–2 ft) if the bed sits on pavement.
  9. Penn State Extension (York County Master Gardeners). Raised Bed Gardening. A common framed bed is 4 × 8 ft by 1 ft deep — enough for most annual vegetable roots.

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