Gravel & Mulch Calculator
Enter your area, depth, and material type to instantly calculate volume in cubic yards and cubic metres, plus weight in tons and the number of bags needed.
How It Works
Volume is simply Area × Depth, with unit conversions applied:
Volume (ft³) = Area (ft²) × Depth (ft) — convert depth in inches to feet by dividing by 12.
Cubic yards = ft³ ÷ 27
Cubic metres = ft³ × 0.0283168
Material densities (approximate):
- Gravel (crushed stone): ~1,680 kg/m³ (105 lb/ft³)
- Pea gravel: ~1,520 kg/m³ (95 lb/ft³)
- Mulch (shredded wood): ~250 kg/m³ (15.6 lb/ft³)
- Topsoil: ~1,200 kg/m³ (75 lb/ft³)
- Sand: ~1,600 kg/m³ (100 lb/ft³)
Weight (lbs) = Volume (ft³) × density (lb/ft³)
US tons = lbs ÷ 2,000
Metric tonnes = kg (volume in m³ × density in kg/m³) ÷ 1,000
Bags: Most bagged material (gravel, mulch, topsoil) is sold in 50 lb bags. Number of bags = Weight (lbs) ÷ 50, rounded up.
Recommended depths:
- Decorative gravel path: 2–3 inches
- Driveway gravel: 4–6 inches
- Garden mulch: 2–4 inches
- Topsoil for lawn: 4–6 inches
- Sand sub-base for pavers: 1 inch
Frequently Asked Questions
What depth of mulch should I apply?
For weed suppression and moisture retention, apply 2–3 inches of mulch. More than 4 inches can restrict air and water reaching plant roots, and create habitat for pests. Refresh existing mulch layers by raking them before adding new material on top.
Should I buy bulk or bagged material?
Bulk delivery (by the cubic yard) is significantly cheaper for volumes over 2–3 cubic yards and avoids plastic waste. Bagged material is convenient for small projects where you need precise amounts or cannot easily accept a truck delivery. Most suppliers deliver bulk gravel from around 1 cubic yard.
How much does a cubic yard of gravel cover?
1 cubic yard covers approximately 162 ft² at 2 inches deep, 108 ft² at 3 inches, or 81 ft² at 4 inches. Use this calculator to get the exact figure for your specific depth.
Does gravel compact after laying?
Yes. Compacted gravel typically reduces in volume by 10–20 % depending on the stone type and how firmly it is tamped. If you need a specific finished depth, add 15 % to your order to account for compaction. Mulch compacts less — roughly 5–10 % over time as it decomposes.
What is the difference between gravel and crushed stone?
Gravel is naturally rounded by water erosion (pea gravel is a classic example) and is used for driveways, paths, and drainage. Crushed stone is mechanically broken and has angular edges that lock together under load, making it better for structural sub-bases and driveways that need a firm, stable surface.