How to calculate topsoil needed
Multiply the area length by width and the desired topsoil depth. The calculator converts the depth into the same base unit before calculating volume.
In Imperial mode, depth is entered in inches and converted to feet. In Metric mode, depth is entered in centimeters and converted to meters.
Topsoil calculation example
A 20 ft × 10 ft area with 4 inches of topsoil requires about 66.667 cubic feet before adding extra material. That equals about 2.469 cubic yards.
With a 10% allowance, the order volume becomes about 73.333 cubic feet, or approximately 2.716 cubic yards.
How many bags of topsoil do I need?
Bagged topsoil is sold in different package volumes. The calculator divides the adjusted soil volume by the bag volume you enter and rounds the result upward to a whole bag.
For example, with the default Imperial project and a 1-cubic-foot bag, the adjusted 73.333 cubic feet requires 74 bags.
Topsoil bags are not all the same size. Enter the actual package volume shown by the supplier instead of assuming every bag contains the same amount.
Estimating topsoil weight
Weight is estimated by multiplying the adjusted volume by the bulk density entered in the calculator.
The default density is only a planning value. Topsoil weight can change considerably with soil composition, organic matter, moisture and compaction.
Use supplier or project-specific bulk-density information when accurate weight is important, especially for delivery, hauling or load planning.
Why add extra topsoil?
Finished grade calculations do not always account for settlement, uneven ground, compaction, spillage or small measurement errors. The allowance field lets you add a percentage before ordering.
Set the allowance to zero when you want only the geometric volume.
Bulk topsoil vs. bagged topsoil
Larger landscaping projects are often supplied as loose material by volume, while small projects may use bags. This calculator reports both a bulk volume and a whole-bag estimate.
Optional pricing can be based on a bag or on bulk volume. Use the same price basis shown in the supplier quote.
Topsoil vs. mulch, sand and gravel
Topsoil is estimated by volume in a similar way to other loose landscape materials, but the material itself and its bulk density are different.
For mulch, use the Mulch Calculator. For sand, use the Sand Calculator. For gravel, use the Gravel Calculator.
This calculator estimates material quantity from the dimensions you provide. It does not determine the correct soil type, planting specification, drainage design, grading requirement or required depth for a particular landscaping project.
Frequently asked questions
How many cubic yards of topsoil do I need?
Multiply length by width and depth in feet to calculate cubic feet, then divide by 27 to convert cubic feet to cubic yards.
How many bags of topsoil do I need?
Divide the required soil volume by the volume printed on one bag, then round upward to the next whole bag.
Why is topsoil density editable?
Topsoil density varies with moisture, mineral content, organic matter and compaction, so one fixed weight conversion is not reliable for every product.
Does the calculator include extra material?
Yes. The adjustable allowance increases the calculated volume, weight and bag quantity.
Can I estimate topsoil cost?
Yes. Enter the supplier price and choose either per-bag pricing or the matching bulk-volume price basis.
Using this calculator effectively
The Topsoil Calculator estimates soil volume from project length, width and depth. It reports bulk volume, whole-bag quantity and approximate weight using an editable bulk density, with optional extra allowance and cost.
Common uses
- Estimating topsoil for lawns, raised beds, garden areas, filling and landscaping.
- Converting a bulk topsoil requirement into a whole-bag quantity using the package volume printed on the bag.
- Estimating approximate soil weight and material cost before ordering or arranging delivery.
Tips for a better estimate
- Measure the actual area and intended finished soil depth rather than relying on rough dimensions.
- Enter the actual bag volume when buying packaged topsoil because package sizes vary.
- Use supplier or project-specific bulk density when weight matters because soil density changes with composition, moisture and compaction.
Related calculations
Cubic Yard Calculator · Gravel Calculator · Mulch Calculator