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Kalcufy

Mulch & Gravel Calculator

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.

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.