Start with the area you will cover
Measure the actual bed or path, not the whole property. Use a tape measure and write down each measurement in the same unit. Measure length and width in feet for US inputs, or meters for metric inputs. Enter the finished material depth separately in inches or centimeters.
Break awkward shapes into simple ones
Split an L-shaped bed into two rectangles that do not overlap. Measure each rectangle and add it as its own area in the calculator. For a round bed, measure straight through the center from edge to edge: that is its diameter, not its radius. For a triangle, calculate half the area of the surrounding rectangle, then enter a rectangle with the same length and half the width.
Check depth in several places
For a refresh, estimate the additional depth you need rather than applying the full target depth over existing material. Uneven ground changes the quantity. Take several depth readings and use a representative average for an initial estimate; use separate areas where depths differ substantially.
Keep an allowance separate
Our tools start with a 5% planning allowance. This is an editable example, not a universal installation requirement. Gravel compaction, irregular edges, spillage and delivery increments can change the order. Ask your supplier or installer which allowance is appropriate before buying.
Example: two garden beds
A 12 × 8 ft bed and a 6 × 4 ft bed total 120 square feet. At 3 inches deep, they require 30 cubic feet, or 1.111 cubic yards. A 5% allowance raises the planning amount to 1.167 cubic yards. At 2 cubic feet per bag, round up to 16 bags.
Put your measurements to work.
Calculate volume, adjust your allowance and save a link to your estimate.
Open the calculator ↗