Mulch Calculator

Calculate how much mulch you need for garden beds, tree rings, and pathways โ€” with bag estimates by mulch type and coverage area

Units:
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Results

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About This Tool

Mulch is one of the best investments in any garden โ€” it retains moisture, suppresses weeds, regulates soil temperature, and gives beds a finished look. But buying the wrong amount wastes money. Too little leaves bare patches where weeds break through. Too much can suffocate plant roots and trap excess moisture. This calculator takes your bed dimensions, factors in the mulch type (each has a different weight and coverage), and tells you exactly how many cubic yards or bags to buy. Choose from bark mulch, wood chips, straw, rubber mulch, or cocoa shell โ€” each with accurate density values for weight estimates. Most garden beds need 2โ€“3 inches of mulch. Tree rings need 3โ€“4 inches. Playground surfaces need 6+ inches for safety. Enter your area, pick your depth, and get a precise order โ€” no more guessing at the garden center.

How to Use

1. Select a project type (flower bed, tree ring, pathway, etc.) for recommended depth 2. Choose your mulch type โ€” each has a different weight per volume 3. Toggle between Rectangle and Circle shapes 4. Toggle between Imperial (ft, in) and Metric (m, cm) 5. Enter dimensions: length and width (or diameter) and depth 6. Adjust waste factor if needed (default 10%) 7. See total volume, weight, and bag estimates

Formula

Rectangle: Volume = Length ร— Width ร— Depth Circle: Volume = ฯ€ ร— (Diameter / 2)ยฒ ร— Depth Weight = Volume ร— Mulch Density Bags = Volume รท Bag Size (2 cu ft standard)

Frequently Asked Questions

How much mulch do I need for a flower bed?
Measure length ร— width of the bed in feet, multiply by desired depth in inches, then divide by 324 to get cubic yards. For a 10ร—4 foot bed with 3 inches of mulch, you need about 0.37 cubic yards or 5 standard 2-cubic-foot bags. Add 10% for waste and settling.
How deep should mulch be?
Most garden beds need 2โ€“3 inches of mulch. Tree rings should be 3โ€“4 inches deep but kept 6 inches away from the trunk. Playground mulch needs at least 6 inches (up to 12 inches under tall equipment) to meet safety standards. Vegetable gardens typically use 2 inches of straw or wood chips.
How many bags of mulch do I need?
Standard mulch bags are 2 cubic feet. One cubic yard equals 27 cubic feet, or about 13.5 bags. For a 100 sq ft area at 3 inches deep, you need about 25 cubic feet โ€” roughly 13 bags. This calculator does the math for any size and shape.
How many cubic yards of mulch do I need for 1000 square feet?
At 2 inches deep: 6.2 cubic yards. At 3 inches deep: 9.3 cubic yards. At 4 inches deep: 12.3 cubic yards. One cubic yard of mulch covers about 162 sq ft at 2 inches, 108 sq ft at 3 inches, or 81 sq ft at 4 inches.
What is the best type of mulch for garden beds?
Bark mulch and shredded hardwood are the most popular for ornamental beds โ€” they look clean, decompose slowly, and suppress weeds effectively. Wood chips are great for pathways and larger areas. Straw is ideal for vegetable gardens. Rubber mulch lasts longest but doesn't enrich soil. Cocoa shell mulch smells great but is toxic to dogs.
When should I replace mulch?
Most organic mulches need topping up once a year. Bark mulch lasts 1โ€“2 years before it decomposes. Wood chips last 1โ€“3 years. Straw decomposes in one season. Rubber mulch can last 10+ years. Before adding new mulch, check existing depth โ€” you only need to top up to the target depth, not add a full new layer on top.
Should I remove old mulch before adding new mulch?
Usually no. Decomposing organic mulch adds nutrients to the soil. Simply top up to your target depth (2โ€“3 inches total). Only remove old mulch if it's matted, moldy, or if you're switching to a completely different type. If existing mulch is over 4 inches deep, rake it to reduce the layer before adding more.

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