The number you need depends on what kind of soil you’re moving, how wet it is, and whether it’s loose or compacted. That 75-pound average only holds for dry bagged topsoil. Grab a shovel full of wet clay, and you’re lifting over 110 pounds per cubic foot — close to the weight of concrete. Underestimate the load and a raised bed could overload a deck; overestimate it and you’re burning time on transport math that doesn’t fit your project. This guide breaks each variable down so you can calculate exactly what your cubic feet weigh.
What Does One Cubic Foot of Soil Weigh?
The short answer is “it depends,” but here are the anchors. Dry topsoil straight from a bag averages 74–80 pounds per cubic foot.
Weight Variations by Soil Type and Moisture
The table below collects the density ranges from the topsoil.com breakdown, the Engineering ToolBox density data, and Caterpillar’s earthwork reference tables. Use these as your planning numbers — match your soil type and moisture level to the column that fits your project.
| Soil Type & Condition | Density (lb/ft³) | Common Use Case |
|---|---|---|
| Dry topsoil (loose) | 56–81 | Bagged garden soil, topping beds |
| Moist topsoil | 81–96 | Typical after a light rain |
| Saturated topsoil | 96–111 | Heavy rain or irrigation runoff |
| Loam | 80 | Standard garden loam blends |
| Dry sand | 97 | Play sand, mortar sand |
| Wet sand | 119 | Beach sand, wet construction sand |
| Dry clay | 100 | Hard-packed subsoil |
| Wet clay | 110 | Waterlogged excavation sites |
| Dry gravel | 105 | Driveway base, drainage |
| Wet gravel | 125 | Pit-run gravel after rain |
How to Calculate the Weight of Any Soil Volume
The formula is simple once you have the right density number. Weight = Volume (cubic feet) × Density (pounds per cubic foot).
First measure your space. For a rectangular bed, measure length, width, and depth all in feet — not inches. Multiply them together to get cubic feet. For a circular planter, measure the diameter, divide by two to get the radius, then multiply radius × radius × 3.14, then multiply by the height. That’s your volume.
Next pick your density factor. If the soil is dry topsoil, use 75. Moist topsoil? Use 90. Wet clay on a jobsite? Use 110 or higher. Multiply your volume by that number.
Example: A 1.5 cubic foot planter box filled with dry topsoil weighs 1.5 × 75 = 112.5 pounds. Fill the same box with wet clay and it hits 1.5 × 110 = 165 pounds. That jump matters if the planter sits on a wooden deck or a balcony.
If you’re in the market for quality soil in that size, you’ll find our review of tested 1.5 cubic foot soil options based on drainage, organic content, and weight.
Why Bagged Soil and Bulk Soil Weigh Differently
That’s because bagged soil is heavily amended with compost, peat moss, and other lightweight organic matter. The bag’s volume is one cubic foot, but its density is roughly half that of mineral-heavy bulk soil.
Conversely, compacted soil that’s been sitting in a pile for months — called “bank” or “packed” soil — can run 85–118 pounds per cubic foot. That’s a 44% increase just from settling and pressure.
For transport planning, remember that a standard pickup truck holds 10–12 cubic yards (270–324 cubic feet). A full load of wet soil can push 24,000 pounds — check your truck’s payload and local road weight limits before loading.
Loose vs. Compacted Soil Density Comparison
The difference between loose and compacted soil is one of the most common mistakes in weight planning. The Caterpillar reference data makes it clear — the same soil type can nearly double in effective density as it settles.
| Soil Type | Loose Density (lb/ft³) | Compacted/Bank Density (lb/ft³) |
|---|---|---|
| Top soil | 59 | 85 |
| Dry packed earth | — | 118 |
| Dry sand | 89 | — |
| Pit-run gravel | — | 135 |
Five Common Mistakes That Throw Off Weight Estimates
Measuring in inches instead of feet. A volume calculated in inches is off by a factor of 1,728 (12³). Always convert depth to feet before multiplying.
Assuming constant weight regardless of moisture. Topsoil.com notes that wet soil can be 30–50% heavier than dry soil. Waterlogged clay exceeds 125 pounds per cubic foot — planning on 75 leaves you dangerously light.
Confusing bag weight with bulk density. A 33-pound bag of compost-rich topsoil doesn’t mean bulk mineral soil weighs the same. Bulk soil is denser — 74 to 110+ pounds per cubic foot.
Using loose density numbers for compacted soil. Packed earth at 118 pounds per cubic foot is far heavier than loose topsoil at 59. If you’re excavating a site that’s been settled for years, use the bank density numbers.
Treating “dirt” and “soil” as interchangeable. Generic loose dirt runs about 76 pounds per cubic foot. Clay runs 100+ pounds. Gravel hits 125 pounds. Naming the exact material changes the weight by 50% or more.
When Soil Weight Gets Dangerous
Soil at 100–120 pounds per cubic foot approaches the weight of concrete (150 pounds per cubic foot). Structural engineers consider this when designing retaining walls, raised bed foundations, and deck load limits. The Ron Meyer excavating reference warns that “Type C” cohesive soils — those under 0.5 tsf shear strength — can range from 110 to 140+ pounds per cubic foot, increasing trench collapse risk when waterlogged. Always check your structure’s load rating before piling wet soil onto a deck or balcony.
FAQs
Does the weight change if the soil has rocks in it?
Yes — rocks like limestone and gravel are denser than organic soil. A cubic foot of limestone weighs about 160 pounds. Even a small percentage of rocks mixed into topsoil will push the per-cubic-foot weight above the dry topsoil average. For load calculations, assume the higher end of the range if you see visible stones.
How much does a 50-pound bag of soil measure in feet?
Bagged soil is less dense than bulk soil because it contains high organic matter, so the bag volume is larger relative to its weight than a bulk yard purchase.
Is it cheaper to buy soil by weight or by volume?
Soil is almost always sold by volume — cubic feet or cubic yards — not by weight. Retailers don’t adjust price for moisture content, so buying dry soil by volume gives you more material per dollar. A cubic yard of dry topsoil contains more actual soil particles than a cubic yard of the same soil when saturated with water.
What happens if I use wet soil calculations for a dry load?
You’ll underestimate the weight by 30–50%, which can cause a vehicle overload, a structural failure in a raised bed, or insufficient shoring in an excavation. Always use the moisture-adjusted density for your specific soil condition — if it’s been raining, plan for saturated weight.
Can I use the same weight estimate for potting mix?
No — potting mix is much lighter than mineral topsoil. It’s made mostly of peat moss, perlite, and bark, so a cubic foot of moist potting mix might weigh only 20–30 pounds. Never use topsoil weight figures for potting mix, or vice versa, because the structural load and transport math will be wildly wrong.
References & Sources
- Engineering ToolBox. “Dirt and Mud Densities.” Density values for dry and moist dirt, loam, sand, clay, and gravel in lb/ft³.