Soil Calculator

Estimate soil for rectangular garden areas and compare loose ordering volume, whole bags and bulk material cost.

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How to Use the Soil Calculator

Add each nonoverlapping area with length and width in feet and intended soil depth in inches. Enter an allowance for settling or handling. Optionally enter bag volume in cubic feet, then choose pricing per bag or per cubic yard.

Formula and Explanation

Target area = Σ(length × width)
Target in-place volume (cu ft) = Σ(length × width × depth in inches / 12)
Loose order volume = target volume × (1 + allowance / 100)
Cubic yards = cubic feet / 27
Bags = ceil(loose order cubic feet / bag cubic feet)

The entered depth describes intended in-place coverage. The adjustable allowance increases the loose volume to order exactly once; it is a user-selected planning assumption, not a measured compaction factor. Bag pricing uses whole rounded-up bags, while bulk pricing uses unrounded loose cubic yards. Bag surplus and supplier selling increments can change the actual order.

Soil density, moisture and settling vary by product and installation. The allowance does not predict final settlement or soil weight. Check supplier guidance, bag labeling, minimum orders and delivery quantities. Irregular beds, slopes, existing soil and root displacement require additional measurement. Delivery, tax and labor are excluded.

Worked Example

A 12 × 9 ft area at 6 inches deep needs 54 cu ft, or 2 cu yd, before allowance. Adding 10% gives 59.4 cu ft, or 2.2 cu yd, of loose order volume. At 2 cu ft per bag, buy 30 bags. At $6 per bag the material estimate is $180; at $50 per cubic yard the separate bulk estimate is $110.

Frequently Asked Questions

Does this calculate settled or loose soil?

The base volume is the target coverage at your entered depth. The allowance increases the loose order estimate. Actual settled volume depends on the soil and installation; the percentage is an assumption you choose.

How many cubic feet are in a cubic yard?

One cubic yard equals 27 cubic feet: three feet in each of three dimensions. Divide the cubic-foot volume by 27 for cubic yards.

Is allowance applied again when counting bags?

No. It is applied once to target volume. Bag count then rounds the allowance-adjusted volume up to whole bags without adding another percentage.

Can I compare bag and bulk prices?

Yes. Enter a bag volume for whole-bag purchases and choose the matching price basis. Bag cost uses rounded bags; cubic-yard cost uses the underlying loose volume. Delivery and supplier increments are separate.