Compost Application Calculator

Enter your area and desired compost depth to get cubic feet, cubic yards, bag counts, and estimated weight. Optional fields estimate added N-P₂O₅-K₂O and organic matter.

Area
Depth & Bags
Optional: Weight & Nutrient Estimates

Compost Needed

Enter dimensions and depth to see volume, bags, and weight.

Area
—
Computed from shape & units
Volume
—
Cubic feet • cubic yards • liters • m³
Bags
—
Counts by each selected bag size
Estimated Weight
—
Uses chosen bulk density
N-P₂O₅-K₂O Applied
—
Total & per 1,000 sq ft (if area known)
Organic Matter Added
—
By weight, from OM%

How to Calculate Compost: Depth × Area → Volume

One cubic yard equals 27 cubic feet and covers 324 ft² at 1 inch depth. The calculator multiplies your area by depth and converts to yards: yd³ = (ft² × in) / 324. In metric, m³ = (m² × cm) / 100.

How Much Compost Should I Use?

  • Top-dressing lawns: 0.25–0.5 in (evenly brushed in).
  • Vegetable/flower beds: 1–2 in on top or 2–3 in mixed into top 6–8 in soil.
  • New beds/poor soil: 2–4 in incorporated.

FAQs — Compost Coverage & Bags

How many bags in a yard of compost?

1 yd³ = 27 cu ft → 27 bags (1 cu ft), 18 bags (1.5 cu ft), or 13.5 bags (2 cu ft).

What does bulk density mean?

It’s the weight per cubic yard. Screened compost averages ~1000 lb/yd³; moisture and feedstock change this widely.

Will compost add nutrients?

Yes, but analysis varies. Typical compost tests around 1-0.5-1 (N-P₂O₅-K₂O). Use soil tests to fine-tune fertilizer needs.