What This Calculator Does

Estimate mulch, soil or topsoil volume from region areas and layer depths. The calculator combines up to 10 regions, reports ft³, yd³ and m³, rounds up whole bags and compares optional bagged and bulk material costs. Material choice identifies your task without assuming density or recommended depth.

When to Use It

Use it for garden beds, uniform layers and rectangular or circular footprints. Different regions can have different depths. For irregular boundaries, use square footage to measure net area, then choose Known area. For aggregate purchased by weight see gravel.

Inputs Explained

Rectangles need length and width; circles use diameter; known-area mode accepts total area. US mode uses ft, ft² and in depth. Metric mode uses m, m² and cm depth. Bag volume can be ft³, litres or m³. Allowance is 0–100%. Prices and bulk density are optional. Density always uses kg/m³, even with US dimensions.

How the Calculation Works

Region volume = area×depth. Rectangle area = length×width; circle area = π×(diameter/2)². Adjusted volume = sum of regions×(1+allowance/100). Whole bags = ceiling(adjusted volume/bag volume). Bag cost = whole bags×bag price. Bulk cost uses unrounded volume priced per yd³ in US mode or per m³ in metric. Metric tonnes = volume in m³×entered density/1000.

Example

For 100 ft² at 3 in deep, depth is 0.25 ft and volume is 25 ft³, approximately 0.925926 yd³ or 0.707921 m³. With 2 ft³ bags and no allowance, 25/2=12.5, so buy 13 bags. At an illustrative price of 4 per bag the material cost is 52. Bulk at an example 50 per yd³ costs about 46.2963. Delivery may change the real comparison.