How Much Gravel or Mulch Do I Need? (Simple Landscaping Calculator)

Sometimes when starting a landscaping project, we need to calculate how much material to order.

This could be soil, gravel, bark mulch, or other garden materials.

If you order too little, you will need another delivery.
If you order too much, you may waste money.

So it helps to know a simple way to calculate the amount.

In landscaping work, we usually use three units:

Their sizes are:

Inches are used for small measurements, such as the thickness of wood or materials.

Feet are used for measuring garden spaces, like the width and length of a yard.

Yards are larger units.
It’s the same “yard” used in golf.

Landscape materials are usually sold in cubic yards.

A cubic yard means:

Length (yard) × Width (yard) × Height (yard)

This gives the volume of the material.

First, calculate the area of the space where you will place the material.

Area is:

Length × Width

For squares or rectangles this is easy.

For irregular shapes, simply divide the space into several smaller sections.
Calculate each section and add them together.

This will give you the total square footage.

Garden areas are usually measured in feet, but the thickness of materials is often measured in inches.

So be careful with the units.

For example:

Garden area = 700 square feet
Gravel thickness = 3 inches

First convert the inches to feet.

3 inches = 3 / 12 feet

Now calculate the volume:

700 × 3/12 = 175 cubic feet

Landscape materials are sold in cubic yards.

One cubic yard equals:

27 cubic feet

(3 × 3 × 3 = 27)

So now divide the number by 27.

175 ÷ 27 = 6.48… cubic yards

Landscape supply stores usually sell materials in 0.5 yard unit.

So in this example, you would order:

6.5 cubic yards

If the theory feels complicated, you can simply remember this formula:

Area (square feet) × Thickness (inches) ÷ 12 ÷ 27

This will give you the amount in cubic yards.

Written by Andy Lee
Owner of Andy’s Landscape Inc. – Landscape Contractor in Maple Ridge, BC