Topsoil Calculator

Topsoil Calculator helps you instantly figure out exactly how many cubic yards of dirt you need for your project. Stop guessing and buy the right amount today.

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Why You Need Accurate Soil Measurements

Dirt is heavy. If you order too much from your local landscape supply, you have a giant pile sitting in your driveway with nowhere to put it. If you buy too little, you have to pay for bulk soil delivery a second time.

Most soil is sold by volume, not weight. You usually buy it in cubic yards (bulk) or cubic feet (bags). To get the math right, you just need three basic numbers: length, width, and depth.

Real-World Scenarios and The Math

Let’s look at a very common scenario. You are building a new 8×4 raised wooden planter.

1. You measure your box. It is 8 feet long and 4 feet wide.
2. Your total square footage is 32 square feet.
3. You want the soil depth to be 10 inches inside the box.

If you just guess the volume, you might drive to the hardware store and put 15 bags in your car. But the math shows this specific box needs almost exactly 1 cubic yard of dirt. A standard bag of dirt holds 0.75 cubic feet. Because one yard equals 27 cubic feet, you actually need 36 bags to fill that single box. Buying loose soil from a dump truck is much cheaper in this scenario.

Another scenario is yard grading. You have a low spot holding water near your fence. You measure the low area at roughly 10×10 feet, and it dips down about 3 inches. You need roughly 1 cubic yard to level it out.

The Compaction Rate Factor (Don’t Forget This)

Dirt contains trapped air. When you dump it into a hole and add water, it shrinks. We call this the compaction rate or settling.

• Always add 10% to 15% extra volume to your final order.
• If you need exactly 5 yards for a deep trench, order 5.5 yards.
• If you don’t add this extra buffer, your filled hole will dip lower than the surrounding grass after the first heavy rain.

Recommended Depth by Project Type

Different jobs require completely different amounts of dirt. Here is a cheat sheet to help you plan your depth before you run the numbers.

Project Type	Recommended Depth	Soil Type Advice
Topdressing an existing lawn	0.25 to 0.5 inches	Use finely screened loam. Avoid big wood chips.
Seeding a brand new grass lawn	4 to 6 inches	Use a 50/50 mix of topsoil and compost mix.
Filling a standard raised bed	8 to 12 inches	Needs excellent drainage. Avoid dense clay.
Patching small yard holes	Varies (fill to top)	Tamp it down hard to speed up settling.

Buying Bulk vs. Buying Bags

Knowing how to buy your dirt saves you money. Use this simple rule:

• Under 1 cubic yard: Buy bags from a local garden center. It is easier to move, and you don’t pay high delivery fees.
• 1 to 2 cubic yards: You can pick this up in a standard pickup truck if it can handle the weight.
• Over 3 cubic yards: Always pay for bulk soil delivery. It takes roughly 9 to 14 wheelbarrow loads to move a single yard from your driveway to your backyard.

Frequently Asked Questions (FAQs)

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Sources & References

• University of Minnesota Extension: Soil compaction causes, pore space, and effects
• Oklahoma State University Extension: Basics of Soil Bulk Density and Porosity

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