Rock Mulch Calculator
Calculate decorative rock, gravel, bark dust, and stone by weight (tons) and cubic yards. Works for pea gravel, river rock, lava rock, and all rock mulch types.
Rock vs Bark - Weight & Cost Comparison
Enter your area to compare the weight and estimated cost of rock mulch vs bark dust for the same coverage area.
Rock Mulch - A Permanent Low-Maintenance Alternative
Rock mulch (decorative gravel, river rock, pea gravel, and crushed stone) is a permanent alternative to organic mulch. It never decomposes, never needs replacing, suppresses weeds effectively, and works especially well in hot, dry climates and xeriscape gardens. The tradeoff: it does not improve soil health, heats up significantly in summer, and is heavy to install and difficult to remove.
Rock Mulch Types - Complete Reference
| Rock Type | Best Use | Weight / Cu Yd | Depth | Cost / Ton |
|---|---|---|---|---|
| Pea Gravel | Pathways, playgrounds, drainage | ~2,800 lbs | 2–3" | $25–$55 |
| River Rock (small) | Beds, borders, water features | ~2,700 lbs | 2–3" | $50–$100 |
| River Rock (large) | Slopes, drainage, accent | ~2,650 lbs | 3–4" | $60–$130 |
| Crushed Limestone | Driveways, paths, base layers | ~2,900 lbs | 2–4" | $20–$45 |
| Lava Rock | Desert/xeriscape, accent beds | ~3,000 lbs | 2–3" | $75–$160 |
| Decomposed Granite | Pathways, xeriscape, driveways | ~2,700 lbs | 3–4" | $35–$65 |
| Pumice | Lightweight accent, succulent beds | ~1,800 lbs | 2–3" | $80–$150 |
Bark Calculator and Bark Dust Calculator
Bark dust (also called bark fines, fine bark, or decorative bark) is a common Pacific Northwest alternative to rock mulch. Unlike gravel, bark dust is organic, improves soil health, and is much lighter to install. The bark calculator yards formula is the same as for wood mulch: Area × Depth in feet ÷ 27 = Cubic Yards. At 2 inches, one cubic yard of bark dust covers approximately 162 sq ft. Use the calculator above by selecting "Bark Dust / Fine Bark" from the material dropdown.
Bark Dust Calculator - Yards Reference
| Area (sq ft) | Bark Dust @ 2" | Bark Dust @ 3" | Bark Chips @ 3" |
|---|---|---|---|
| 100 sq ft | 0.62 yds | 0.93 yds | 0.93 yds |
| 200 sq ft | 1.23 yds | 1.85 yds | 1.85 yds |
| 500 sq ft | 3.09 yds | 4.63 yds | 4.63 yds |
| 1,000 sq ft | 6.17 yds | 9.26 yds | 9.26 yds |
Barkdust Calculator - What Makes Bark Dust Different
Bark dust is the finest grade of processed bark, with particles typically under 1/2 inch. This fine texture creates a dense, weed-suppressing surface that is popular in Pacific Northwest landscaping. The barkdust calculator uses the same volume formula as any other mulch, but with these key differences: bark dust settles 15–20% (more than wood chips or nuggets), so always add a 15–20% buffer to your calculated quantity.
Rock vs Bark Mulch - Which Should You Choose?
| Factor | Rock Mulch | Bark / Wood Mulch |
|---|---|---|
| Lifespan | Permanent | 1–4 years |
| Long-term cost | Lower (no replacement) | Higher (annual top-dressing) |
| Installation weight | Very heavy (1–1.5 tons/yd) | Light (0.2–0.35 tons/yd) |
| Summer heat | Gets very hot in sun | Stays cooler |
| Soil health | No benefit | Improves soil as it decomposes |
| Weed suppression | Good (with fabric underneath) | Good at 3"+ depth |
| Removal if needed | Very difficult and expensive | Easy - decomposes in place |
| Best climate | Dry, hot (low-water landscapes) | All climates |
Front Yard Rock Mulch - Landscape Design Tips
Rock mulch for front yards works best with drought-tolerant plants (ornamental grasses, lavender, salvia, sedum) and modern or desert landscape styles. Install landscape fabric beneath rock mulch to prevent gravel from mixing into soil over time. Use edging to contain rock at bed boundaries. For high-visibility front yard applications, river rock (small) or decomposed granite offer the most polished appearance.
Use the formula: (Length × Width × Depth in feet) ÷ 27 = Cubic Yards. For bark dust at 3 inches: multiply your square footage by 0.25, then divide by 27. Example: 500 sq ft × 0.25 ft = 125 cu ft ÷ 27 = 4.63 yards. Add 15–20% for bark dust settling: 4.63 × 1.18 = approximately 5.5 yards total.
Rock mulch alone is not better - it still allows weeds through unless combined with landscape fabric underneath. With fabric, rock mulch provides excellent long-term weed suppression. Without fabric, weeds grow readily in the organic matter that accumulates between rocks over time. Wood mulch at 3–4 inches provides comparable weed control without needing fabric.
This calculator handles both rock mulch (by tons and cubic yards) and bark/bark dust (by cubic yards and weight). For bark dust specifically, use the material dropdown and select the bark type to get settling-adjusted calculations. For rock mulch, the calculator outputs both cubic yards (for supplier ordering) and tons (for delivery pricing - most rock suppliers quote by the ton).