Rectangle: length and width
Measure two adjacent sides. Multiply length by width. A 10 × 12 ft bed covers 120 square feet.
Circle: radius, not diameter
The radius runs from the center to the edge. If you measured the full width across a circle, divide that diameter by two. Area = π × radius².
Triangle: base and perpendicular height
Measure straight from the opposite point to the base at a right angle. A sloping side is not the height. Area = base × perpendicular height ÷ 2.
Irregular shapes: split, then add
Sketch the bed and divide it into sections that approximate rectangles or triangles. Add each section as a separate area with the same material. Do not overlap the sections, or you will count that volume twice.
For an L-shaped bed, one workable split is a long rectangle plus the remaining shorter rectangle. Subtract paths and spaces occupied by permanent objects from your measured sections before entering them.
Choose consistent units
There are 12 inches in 1 foot. To enter 10 ft 6 in, use either 10.5 feet or 126 inches. Both dimensions within an area use the selected dimension unit. Depth has its own unit selector.
Measure the depth you will add
For mulch, use your chosen installation depth. For raised beds, use the actual empty fill depth and inside dimensions. Check multiple spots on uneven ground; this tool assumes a uniform depth within each area.
Before you order
- Double-check radius versus diameter and perpendicular height versus a sloping side.
- Make sure the selected unit matches your measurement.
- Review the product’s bag volume or supplier’s bulk units.
- Verify that a minimum order and increment match your supplier’s quotation.