Peat Moss Calculator
Calculate compressed peat moss bales needed to amend or top-dress an area.
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What this tool does
Peat moss is sold compressed and roughly doubles in volume when loosened. This calculator finds the loose volume you need for an area and depth, then divides by the expanded bale volume to tell you how many bales to buy.
How to use the Peat Moss Calculator
- Enter the area length and width.
- Enter the depth to apply or mix in.
- Choose the compressed bale size.
- Buy the bales shown.
Formula
Bales = ⌈L × W × (D ÷ 12) ÷ (bale × 2)⌉
- L, W
- Feet
- D
- Inches
- bale × 2
- Approximate loose volume of a compressed bale
Worked example
Mixing 2 inches of peat into a 20 × 10 ft bed with 3.8 cu ft bales.
Inputs
- Length20 ft
- Width10 ft
- Depth2 in
- Bale size (compressed)3.8 cu ft (expands to ~7.6)
Result
- Bales needed5
- Loose volume needed33.33 cu ft
- Cubic yards1.23 cu yd
Results explained
- Bales
- Compressed bales to buy.
- Loose volume
- Fluffed peat needed.
- Cubic yards
- Same in yards.
Frequently asked questions
A 3.8 cu ft bale expands to about 7.6 cu ft — roughly 45 sq ft at 2 inches deep.
Mix 1–2 inches into the top 6–8 inches, or up to 25% of a container mix.
Yes. Dry peat repels water; moisten it before mixing.
Yes, sphagnum peat is acidic (pH 3.5–4.5) — helpful for blueberries and azaleas.
Coco coir and compost are common renewable alternatives.