";}else{var dia=parseFloat(document.getElementById('input1').value);if(isNaN(dia)||dia<=0){alert("Please enter a valid diameter.");return;}var radius=dia/2;area=Math.PI*Math.pow(radius,2);details="Radius = "+radius.toFixed(2)+" ft
Area = π x "+radius.toFixed(2)+"² = "+area.toFixed(2)+" sq ft
";}var depthFt=d/12;var cubicFt=area*depthFt;var cubicYd=cubicFt/27;var bags2=cubicFt/2;var bags3=cubicFt/3;document.getElementById('resultsMain').innerHTML=cubicYd.toFixed(2)+" Cubic Yards
or "+cubicFt.toFixed(2)+" Cubic Feet";var stepText=details+"Depth in feet = "+d+" / 12 = "+depthFt.toFixed(4)+" ft
"+"Cubic Feet = Area x Depth = "+cubicFt.toFixed(2)+" cu ft
"+"Cubic Yards = Cubic Feet / 27 = "+cubicYd.toFixed(2)+" cu yd
"+"
Bag Equivalents:
"+Math.ceil(bags2)+" bags (2 cu ft each)
"+Math.ceil(bags3)+" bags (3 cu ft each)";document.getElementById('stepsOutput').innerHTML=stepText;document.getElementById('stepsOutput').style.display=steps?'block':'none';}function resetCalc(){document.getElementById('resultsMain').innerHTML='—';document.getElementById('stepsOutput').style.display='none';setTimeout(toggleInputs,10);}
Mulch Calculator Use
Plan your landscaping project with precision using our mulch calculator. Whether you are refreshing your flower beds for spring or installing a new garden path, knowing exactly how much material to order saves you money and prevents multiple trips to the garden center. This tool handles both rectangular and circular areas and provides results in cubic yards, cubic feet, and standard bag counts.
- Length & Width / Diameter
- Measure the surface area of your garden bed in feet. For irregular shapes, it is best to break them into smaller rectangles or circles and sum the results.
- Desired Depth
- The industry standard for weed suppression and moisture retention is 2 to 4 inches. Enter your preference in inches.
- Bag Sizes
- The calculator automatically converts your volume into the number of bags needed, typically sold in 2 or 3 cubic foot increments.
How It Works
To calculate the volume of mulch required, we first determine the square footage of the area and then multiply it by the thickness of the mulch layer. The formula used by the mulch calculator is:
Volume (Cubic Yards) = [(Area in sq ft) × (Depth in inches / 12)] / 27
- Area: Length multiplied by Width for rectangles, or π × r² for circles.
- Depth Conversion: We divide the inches by 12 to convert the measurement to feet, ensuring units are consistent.
- Cubic Yard Conversion: Since bulk mulch is sold by the cubic yard, we divide the total cubic feet by 27 (the number of cubic feet in one cubic yard).
Calculation Example
Example: You have a front yard garden bed that is 20 feet long and 5 feet wide. You want to apply a 3-inch layer of cedar mulch.
Step-by-step solution:
- Calculate Area: 20 ft × 5 ft = 100 sq ft.
- Convert Depth: 3 inches / 12 = 0.25 ft.
- Calculate Cubic Feet: 100 sq ft × 0.25 ft = 25 cu ft.
- Convert to Cubic Yards: 25 / 27 = 0.926 cu yd.
- Result: You need approximately 0.93 cubic yards or 13 bags (if using 2 cu ft bags).
Common Questions
How deep should I apply mulch?
For most ornamental beds, a depth of 2 to 3 inches is ideal. If you are using mulch for a play area or a path, you might go as deep as 4 to 6 inches for better cushioning and durability. Avoid "volcano mulching" (piling it against tree trunks), which can cause rot.
Is it cheaper to buy bulk mulch or bags?
Bulk mulch is almost always cheaper per cubic yard, especially for large projects. However, you must factor in delivery fees. For small projects requiring less than 1 or 2 cubic yards, bags are often more convenient because they are easier to transport and place in tight spaces.
Does mulch settle over time?
Yes. Organic mulches like wood chips or bark will decompose and settle. It is standard practice to add a "top-off" layer of about 1 inch every year or two to maintain the desired depth and color. When using the mulch calculator for a brand-new bed, it is often wise to round up your result to account for this initial settling.