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Mulch Calculator

Calculate mulch, gravel, or stone needed for landscaping. Get cubic yards, bags, weight, and cost comparison for rectangle, circle, or triangle beds.

2" refresh · 3" standard · 4" new beds

0%25%
0.98 cu yd
total volume needed
Area
96 sq ft
Volume
26.4 cu ft
Bags (2 cu ft)
14
Weight
0.26 tons
Bagged
$56.00
14 bags × $4.00/bag
Bulk Best value
$34.22
0.98 yd³ × $35.00/yd

How to Calculate Mulch

Select your bed shape, enter dimensions and depth, then the calculator does the rest. The formula varies by shape:

  • Rectangle: Area = Length × Width
  • Circle: Area = π × (Diameter ÷ 2)²
  • Triangle: Area = Base × Height ÷ 2

Volume in cubic yards = Area (sq ft) × Depth (inches) ÷ 324. The overage factor adds extra to account for waste, settling, and uneven ground.

Recommended Depths

  • 2 inches: Light refresh of existing beds
  • 3 inches: Standard coverage for most beds (most common)
  • 4 inches: New beds or heavy weed suppression
  • 6 inches: Pathways with heavy foot traffic

Never apply mulch deeper than 4 inches around plants. Excessive depth suffocates roots and traps moisture, causing rot.

Coverage Chart (per cubic yard)

  • 2" deep: 162 sq ft
  • 3" deep: 108 sq ft
  • 4" deep: 81 sq ft

A standard 2 cu ft bag covers about 8 sq ft at 3 inches deep. One cubic yard equals roughly 13.5 bags.

Bulk vs Bagged Mulch

  • Bagged ($3-8 per bag): Convenient for small beds under 200 sq ft, easy to transport and store
  • Bulk ($30-120 per cubic yard): 30-50% cheaper for large projects, delivered by truck

For areas over 200-300 sq ft, bulk is almost always more economical. The calculator compares both options and labels the cheaper one as "Best value." A cubic yard of mulch weighs 400-800 lbs depending on material and moisture content.

Measuring Irregular Shapes

For beds that aren't a clean rectangle, circle, or triangle:

  • Break it up: Divide complex beds into simpler shapes. Calculate each separately and add the totals.
  • Curved beds: Use the circle shape for round beds, or approximate with a rectangle using the widest and longest measurements.
  • Corner beds: A triangle works well for wedge-shaped beds along a fence corner or wall intersection.

Choosing the Right Material

  • Shredded bark: Best all-around. Affordable, stays in place, decomposes to enrich soil
  • Wood chips: Longer lasting than bark. Better for pathways than garden beds
  • Pine straw: Naturally acidic — great for azaleas, blueberries, and rhododendrons
  • Rubber mulch: Permanent, doesn't decompose. Best for playgrounds, not gardens
  • Pea gravel: Decorative with excellent drainage. Won't decompose or attract pests
  • River rock: Permanent solution, no annual replacement. Retains heat in summer

Application Tips

  • Keep mulch 3-6 inches away from tree trunks and plant stems — build a donut shape, not a volcano
  • Organic mulch needs refreshing every 1-2 years as it decomposes
  • Best time to buy: mid-spring to early summer when stores run promotions (up to 40% off)
  • Lay landscape fabric underneath for extra weed suppression, especially with rock or gravel
  • Top up annually when depth drops below 2 inches

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Frequently Asked Questions

How deep should mulch be?

2-3 inches for refreshing existing beds, 3-4 inches for new beds. Avoid going over 4 inches as it can suffocate plants.

How much does a cubic yard of mulch cover?

One cubic yard covers about 162 sq ft at 2 inches deep, 108 sq ft at 3 inches, or 81 sq ft at 4 inches.

Should I buy bagged or bulk mulch?

Bulk is cheaper for large areas (500+ sq ft). Bags are convenient for small beds and easier to transport. This calculator compares both options so you can see the price difference.

How often should I replace mulch?

Wood mulch decomposes and needs refreshing yearly. Rubber mulch and stone last much longer.

How do I measure a circular flower bed?

Measure the diameter (distance across the widest point). The calculator uses pi times radius squared to compute the area automatically.

How do I measure a triangular bed?

Measure the base (longest side) and the perpendicular height from that base to the opposite corner. The calculator uses base times height divided by two.

What is the overage/waste factor?

Extra material to account for spillage, uneven ground, and settling. 10% is standard. Use 15-20% for irregular terrain or beds with curves.

How do I convert bags to cubic yards?

A standard 2 cu ft bag is about 0.074 cubic yards. One cubic yard equals roughly 13.5 bags of 2 cu ft mulch.