Peat Moss Calculator

Peat Moss Coverage Calculator

1.0 cu. ft. 2.2 cu. ft. 3.0 cu. ft. 3.8 cu. ft. (Standard)

Results:

Total Loose Volume Needed: 0 cubic feet

Number of Bales (at 2x expansion): 0 bales

Estimated Total Cost: $0.00

*Note: Most peat moss is compressed in the bale. We calculate based on a standard 2:1 expansion ratio (1 cu. ft. compressed = ~2 cu. ft. loose).

function calculatePeatMoss() { var length = parseFloat(document.getElementById('pm_length').value); var width = parseFloat(document.getElementById('pm_width').value); var depth = parseFloat(document.getElementById('pm_depth').value); var baleSize = parseFloat(document.getElementById('pm_bale_size').value); var costPerBale = parseFloat(document.getElementById('pm_cost').value) || 0; if (length > 0 && width > 0 && depth > 0) { // Calculate loose cubic feet needed // Area (sq ft) * Depth (ft) var looseVolumeNeeded = length * width * (depth / 12); // Peat moss typically expands 2x when loosened // So, 1 compressed cubic foot = 2 loose cubic feet var looseVolumePerBale = baleSize * 2; var balesNeeded = Math.ceil(looseVolumeNeeded / looseVolumePerBale); var totalCost = balesNeeded * costPerBale; document.getElementById('res_volume').innerText = looseVolumeNeeded.toFixed(2); document.getElementById('res_bales').innerText = balesNeeded; document.getElementById('res_total_cost').innerText = '$' + totalCost.toFixed(2); document.getElementById('pm_results').style.display = 'block'; } else { alert('Please enter valid positive numbers for length, width, and depth.'); } }

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How to Use the Peat Moss Calculator

Calculating the correct amount of peat moss is essential for soil conditioning, seed starting, and garden bed preparation. Because peat moss is typically sold in compressed bales, calculating the volume requires understanding the "expansion ratio."

The Science of Peat Moss Volume

When you buy a bale of peat moss, the packaging usually lists the compressed volume (e.g., 3.8 cubic feet). Once you open the bale and fluff the material, it expands. Most high-quality sphagnum peat moss expands at a 2:1 ratio. This means a 3.8 cubic foot bale will actually cover roughly 7.6 cubic feet of loose garden space.

Step-by-Step Calculation Guide

1. Measure your area: Find the length and width of your garden bed in feet.
2. Determine depth: Decide how many inches of peat moss you want to incorporate. For soil amendment, 2 to 3 inches is standard.
3. Calculate Square Footage: Length × Width = Total Square Feet.
4. Convert to Cubic Feet: (Square Feet × Depth in Inches) ÷ 12 = Loose Cubic Feet needed.
5. Account for Expansion: Divide the Loose Cubic Feet by (Bale Size × 2).

Realistic Example

Imagine you have a raised garden bed that is 12 feet long and 4 feet wide. You want to add 3 inches of peat moss to improve water retention.

• Square Footage: 12 ft × 4 ft = 48 sq. ft.
• Volume Needed: 48 sq. ft. × (3 / 12) = 12 cubic feet of loose peat moss.
• Bales Required: If using 3.8 cu. ft. bales (which expand to 7.6 cu. ft.), you would need 12 ÷ 7.6 = 1.57 bales.
• Result: You should purchase 2 bales to ensure full coverage.

Why Use Peat Moss?

Peat moss is a sterile, organic material that is highly absorbent. It can hold several times its weight in water, releasing it slowly to plant roots. It is also excellent for acid-loving plants like blueberries, azaleas, and camellias because it has a naturally low pH (acidic).

Pro Tip: Always moisten peat moss before mixing it into your soil. Dry peat moss is hydrophobic (repels water), so pre-soaking it ensures it integrates properly with your existing garden soil.