Screened Topsoil Calculator: Volume & Cost

A screened topsoil calculator works out how many cubic yards or cubic feet of screened topsoil you need for a garden bed, lawn base, or fill project. You enter the length and width of the area in feet, plus the depth you want in inches, and it returns the volume in cubic yards and cubic feet. This article explains the formula, how to use it, how to choose the right depth, and common pitfalls like compaction and over-ordering.

Formula

The volume of topsoil is simply length times width times depth, but you must keep the units consistent. Since you measure the area in feet and the depth in inches, the formula is:

Volume (ft³) = Length (ft) × Width (ft) × Depth (in) / 12

To get cubic yards, divide by 27 (since 1 yd³ = 27 ft³):

Volume (yd³) = Length (ft) × Width (ft) × Depth (in) / 324

The constant 324 comes from 12 inches per foot × 27 cubic feet per cubic yard. If you measure in meters and centimeters, the equivalent formula is Volume (m³) = Length (m) × Width (m) × Depth (cm) / 100, then divide by 1.3 to get cubic yards (1 yd³ ≈ 0.7646 m³).

Worked Example

Using the default values from the calculator: a lawn 40 ft long, 25 ft wide, and 3 inches deep.

1. Convert depth to feet: 3 in ÷ 12 = 0.25 ft
2. Calculate cubic feet: 40 × 25 × 0.25 = 250 ft³
3. Convert to cubic yards: 250 ÷ 27 = 9.26 yd³

The calculator shows 9.26 yd³ (and 250.0 ft³). That matches the formula output exactly. For a typical residential delivery, you would order 10 yd³ to cover spillage and compaction.

What Is Screened Topsoil?

Screened topsoil is soil that has passed through a mesh screen, usually ½-inch or ¼-inch, to remove rocks, roots, clods, and debris. The result is a uniform, fine-textured soil that spreads easily and provides a consistent growing medium. Unscreened “fill dirt� is cheaper but contains lumps and stones, making it unsuitable for lawns or flower beds. Screened topsoil is also often blended with compost or sand, so check the label or ask the supplier what is actually in the mix.

How to Choose the Right Depth

Depth depends entirely on what you are planting. For a new lawn from seed, 4–6 inches of topsoil is typical. For sod, 3–4 inches is usually enough because the sod itself adds root depth. For vegetable gardens or flower beds, 6–12 inches is better, especially if the native soil is poor. For raised beds, you may need 12–18 inches, but that is often filled with a soilless mix rather than pure topsoil. The calculator lets you adjust depth in inches, but remember that deeper is not always better—excess topsoil can smother existing roots or create drainage issues.

Common Mistakes and How to Avoid Them

• Mixing units: Entering depth in feet instead of inches, or width in yards instead of feet, throws off the result by a factor of 3 or 12. Always double-check your units.
• Forgetting compaction: Fresh topsoil settles. A 3-inch layer may compact to 2.5 inches after watering or rain. Order 10–15% extra to be safe.
• Ignoring slopes: The formula assumes a flat, rectangular area. If your lawn is sloped or irregular, break it into rectangles and add the volumes, or use a more advanced calculator.
• Rounding too early: If you round 9.26 yd³ down to 9, you will be short. Always round up to the next half or whole yard.
• Not accounting for existing soil: If you are only adding a layer on top of existing soil, measure the depth you actually need, not the depth of the bed frame.

Screened vs. Unscreened Topsoil

The main difference is cost and quality. Screened topsoil costs more per yard because it goes through an extra processing step and has less waste. Unscreened topsoil is cheaper but may contain rocks, roots, and clay clumps that you will have to remove by hand. For a lawn, screened is almost always worth it. For filling a large hole or raising a grade where nothing will grow, unscreened fill dirt is a better value. Some suppliers sell “double-screened� topsoil, which is even finer and better for seed beds, but it is also the most expensive.

Cost Considerations and Ordering

Topsoil is sold by the cubic yard, either bulk (delivered by truck) or in bags (usually 0.75–1.0 cubic feet each). Bulk is far cheaper per yard, but you must have a place for the truck to dump and a way to move the soil. Bags are easier for small projects but cost 5–10 times more per yard. When ordering bulk, ask about delivery fees and minimums—many suppliers require at least 5–10 yards. Also ask if the price includes screening and delivery. Always order slightly more than the calculator shows, because compaction and spillage are inevitable.

Alternatives to Screened Topsoil

If screened topsoil is not available or too expensive, consider these alternatives:

• Compost: Great for amending existing soil, but it is not a substitute for topsoil because it breaks down and shrinks.
• Garden mix: A blend of topsoil and compost, often better for beds than pure topsoil.
• Lawn soil: A sandier mix designed for leveling and overseeding, but it lacks nutrients.
• Fill dirt: For non-planting purposes only.

Frequently Asked Questions

How many cubic feet are in a cubic yard of topsoil?

There are 27 cubic feet in one cubic yard. A standard 40-pound bag of topsoil usually contains about 0.75 cubic feet, so you would need about 36 bags to make one cubic yard.

How much topsoil do I need for a 10×10 garden bed?

For a 10×10 ft bed at 6 inches deep, the volume is 10 × 10 × 0.5 = 50 cubic feet, or about 1.85 cubic yards. Round up to 2 cubic yards to account for settling.

Can I use screened topsoil for a raised bed?

Yes, but it is heavy and may compact. Many gardeners prefer a mix of 50% topsoil and 50% compost for raised beds. The calculator still works for volume, but you may want to adjust the mix.

How deep should topsoil be for grass seed?

For grass seed, 4–6 inches of screened topsoil is ideal. Less than 3 inches may dry out quickly and not give roots enough room. For sod, 3–4 inches is usually sufficient.

Does topsoil settle after rain?

Yes, fresh topsoil can settle 10–20% after the first heavy rain or watering. That is why you should order extra and be prepared to add more later.

Is screened topsoil safe for vegetable gardens?

Generally yes, but ask the supplier if the soil has been tested for contaminants. Some bulk topsoil may contain residual herbicides or heavy metals. For food crops, consider a certified organic soil mix.

Related

• Retaining Wall Calculator Australia: Estimate Wall Volume
• Retaining Wall Base Calculator: Estimate Base Volume
• Retaining Wall Block Calculator for Fire Pits

in l | Lawn length | ft | 40 | 0 | 100000
in w | Lawn width | ft | 25 | 0 | 100000
in d | Depth | in | 3 | 0 | 120
out yd | Volume | yd³ | l * w * d / 324 | 2
out ft3 | Volume | ft³ | l * w * d / 12 | 1