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Kalcufy

Mulch & Gravel Calculator

Calculate how much mulch, gravel, stone, or soil you need in cubic yards and bags — with cost estimates.

Reference table

LengthVolume (Cubic Yards)Volume (Cubic Feet)Volume (Cubic Meters)
10.04 cu yd1 cu ft0.03 m³
20.08 cu yd2 cu ft0.06 m³
30.12 cu yd3 cu ft0.09 m³
40.16 cu yd4 cu ft0.12 m³
50.20 cu yd6 cu ft0.16 m³
100.41 cu yd11 cu ft0.31 m³
150.61 cu yd17 cu ft0.47 m³
200.81 cu yd22 cu ft0.62 m³
251.02 cu yd28 cu ft0.78 m³
301.22 cu yd33 cu ft0.93 m³
401.63 cu yd44 cu ft1.25 m³
502.04 cu yd55 cu ft1.56 m³
602.44 cu yd66 cu ft1.87 m³
702.85 cu yd77 cu ft2.18 m³
753.06 cu yd83 cu ft2.34 m³

💡 Application Tips

  • Lay landscape fabric underneath gravel or stone to prevent weed growth and mixing with soil
  • For mulch, leave a 3-6 inch gap around tree trunks — piling mulch against bark causes rot (avoid 'mulch volcanoes')
  • Order 5-10% extra to account for settling, spillage, and uneven ground
  • 1 cubic yard covers about 162 sq ft at 2" deep, 108 sq ft at 3", or 81 sq ft at 4"

Mulch, Gravel & Landscaping Materials

Mulch is any material spread over soil surface to retain moisture, suppress weeds, regulate temperature, and improve appearance. Organic mulches (wood chips, bark, straw) decompose over time, enriching the soil with nutrients. Inorganic mulches (gravel, rubber, stone) are permanent and require less maintenance. Gravel is a loose mixture of rock fragments formed by erosion or mechanical crushing, classified by size using standards like the Udden-Wentworth scale (2-64 mm). It is widely used for driveways, drainage, walkways, and decorative landscaping. Common types include pea gravel (small, rounded, inexpensive), crushed stone (angular, interlocking, ideal for bases), and river rock (smooth, decorative). Topsoil and compost are used to establish new garden beds, amend existing soil, and fill raised beds. The right material depends on your project goals: mulch for plant beds, gravel for hardscaping and drainage, and soil for growing.

How This Calculator Works

The calculator computes volume by first determining the coverage area based on your chosen shape (rectangle = length × width, circle = π × radius², triangle = ½ × base × height) or your directly entered area. It then multiplies area by depth to get cubic footage, converts to cubic yards (÷ 27), and applies your waste factor. Weight is estimated by multiplying volume by the material's density — mulch typically weighs 400-800 lbs per cubic yard while gravel weighs 2,400-2,700 lbs. Bag count divides total cubic feet by your chosen bag size and rounds up. Cost is calculated from either your bulk price per cubic yard or per-bag price, plus optional delivery. The calculator also provides metric equivalents (cubic meters, kilograms, square meters) for international users.

Key Considerations

  • Mulch should be 2-3 inches deep for garden beds and 3-4 inches for paths and slopes. Too thick (>4") can suffocate roots and prevent water penetration.
  • Never pile mulch against tree trunks ('mulch volcanos'). Keep a 3-6 inch gap to prevent bark rot, disease, and pest habitat.
  • Gravel for driveways should be 4 inches deep minimum with a compacted base layer. Use angular crushed stone (not rounded) so it interlocks and doesn't shift.
  • Organic mulch decomposes and needs replacing every 1-2 years. Inorganic materials (gravel, rubber) last much longer but don't improve soil.
  • Wet mulch and soil are significantly heavier than dry. A cubic yard of wet soil can weigh 3,000+ lbs. Plan transportation accordingly.
  • Bulk delivery is typically 40-60% cheaper than buying bags for projects needing more than 3 cubic yards. Most suppliers deliver 1-15 yards per load.

Material Type Guide

  • Hardwood Mulch: Most popular choice for flower beds and landscaping. Medium texture, stays in place well, decomposes slowly adding nutrients. Lasts 1-2 years.
  • Pea Gravel: Small, rounded, 3/8" stones available in many colors. Affordable and versatile — great for walkways, patios, drainage, and dog runs. Shifts underfoot.
  • Crushed Stone (#57): Angular 3/4"-1" stones that interlock when compacted. Best for driveways, foundations, and drainage. Provides excellent stability.
  • River Rock: Smooth, rounded 1-3" stones from riverbeds. Decorative accent for beds, water features, and dry creek beds. Won't decompose. Heavy — plan for delivery.
  • Rubber Mulch: Made from recycled tires. Doesn't decompose, suppresses weeds, and cushions falls. Ideal for playgrounds and high-traffic areas. Does not feed soil.
  • Topsoil & Compost: Rich organic material for new garden beds. Use 60% topsoil + 30% compost + 10% perlite for optimal plant growth. Apply 3-6 inches deep for new beds.

Calculation Examples

Step-by-step material estimation

Flower Bed: 20' × 4', Hardwood Mulch, 3" deep

  1. Area = 20 × 4 = 80 sq ft
  2. Depth = 3 inches = 0.25 ft
  3. Volume = 80 × 0.25 = 20 cu ft
  4. Cubic yards = 20 ÷ 27 = 0.74 cu yd
  5. Add 10% waste = 0.74 × 1.10 = 0.81 cu yd
  6. Weight = 0.81 × 25 lbs/ft³ × 27 = ~549 lbs
  7. Bags (2 cu ft) = ⌈22 ÷ 2⌉ = 11 bags

0.81 cu yd ≈ 11 bags of 2 cu ft mulch, weighing about 549 lbs. At $35/yd: ~$28. At $5/bag: ~$55.

Gravel Driveway: 40' × 12', Crushed Stone, 4" deep

  1. Area = 40 × 12 = 480 sq ft
  2. Depth = 4 inches = 0.333 ft
  3. Volume = 480 × 0.333 = 160 cu ft
  4. Cubic yards = 160 ÷ 27 = 5.93 cu yd
  5. Add 10% waste = 5.93 × 1.10 = 6.52 cu yd
  6. Weight = 6.52 × 100 lbs/ft³ × 27 = ~17,604 lbs ≈ 8.8 tons
  7. This is a bulk delivery project (too heavy for bags)

6.52 cu yd of crushed stone, weighing ~8.8 tons. At $45/yd: ~$293 + delivery. Order ~7 yards to be safe.

Frequently Asked Questions

How many cubic yards of mulch do I need?

Measure your area's length and width in feet, multiply them together to get square footage, then multiply by depth in feet (3" = 0.25 ft). Divide the result by 27 to get cubic yards. For example, a 20' × 10' bed at 3" deep needs: (200 × 0.25) ÷ 27 = 1.85 cubic yards. Add 10% for waste, so order about 2 cubic yards.

How much does a cubic yard of mulch or gravel weigh?

Mulch weighs 400-800 lbs per cubic yard depending on moisture and type (wood chips are lighter, hardwood is heavier). Gravel weighs 2,400-2,900 lbs (1.2-1.45 tons) per cubic yard. Topsoil weighs about 2,000-2,200 lbs per cubic yard. Always consider weight when planning transportation — a standard pickup truck can safely carry about 1 cubic yard of mulch but may be overloaded by 1 yard of gravel.

How deep should I apply mulch?

Apply 2-3 inches for most garden beds with fine mulch, and 3-4 inches for coarser mulch, pathways, and slopes. Never exceed 4 inches around plants, as too-thick mulch prevents oxygen and water from reaching roots. For trees, spread mulch in a wide ring (3-6 ft diameter) but keep it 3-6 inches away from the trunk.

Is it cheaper to buy mulch in bulk or bags?

Bulk is typically 40-60% cheaper per cubic yard. One cubic yard of mulch costs $25-50 in bulk vs. $56-94 in bags (14 bags at $4-7 each). However, bags are more convenient for small projects under 2-3 cubic yards, require no delivery fee ($50-150 for bulk), and can be transported in a car. The break-even point is usually around 3 cubic yards.

How many bags of mulch are in a cubic yard?

One cubic yard equals 27 cubic feet. In standard 2 cu ft bags: 27 ÷ 2 = 13.5, so you need 14 bags per cubic yard. In 3 cu ft bags: 27 ÷ 3 = 9 bags per cubic yard. In 0.5 cu ft bags (common for gravel/stone): 27 ÷ 0.5 = 54 bags per cubic yard.

What type of gravel is best for driveways?

Crushed stone (#57 or #411) is ideal for driveways because its angular shape interlocks when compacted, creating a stable surface. Use a 3-layer approach: base layer of large #3 stone (3-4"), middle layer of #57 stone (1"), and top layer of #411 or stone dust for a smooth finish. Total depth should be at least 4 inches. Avoid pea gravel for driveways — it's round and shifts under tires.

How much area does one cubic yard of material cover?

Coverage depends on depth: at 1" deep, 1 cubic yard covers 324 sq ft; at 2" deep, 162 sq ft; at 3" deep, 108 sq ft; at 4" deep, 81 sq ft; at 6" deep, 54 sq ft. The formula is: coverage (sq ft) = 324 ÷ depth (inches). This is useful for quick estimates when you know how many yards a supplier has available.

Should I use landscape fabric under mulch or gravel?

Under gravel and stone — yes, always. Fabric prevents stones from sinking into soil and weeds from growing through. Under organic mulch — usually no. Fabric blocks the mulch from decomposing into the soil (which is a major benefit of organic mulch) and can create a mat where weeds actually root on top. Instead, use a thick layer of mulch (3-4") to naturally suppress weeds in garden beds.

Sources