Mulch Calculator Widget

Embed a mulch, topsoil and compost calculator on a garden centre, landscaper or gardening blog. Visitors enter a rectangular or round bed and a depth, choose the material and bag size, and see the volume, the bags to buy and university extension guidance on how deep to spread it.

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Exactly what your visitors will see

Under the widget on your page: Mulch Calculator by A2Z Tools

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<div data-a2z-widget="mulch-calculator" data-height="680"></div>
<p class="a2z-attribution" style="margin:6px 0 0;font:12px/1.4 system-ui,sans-serif;opacity:.8">Mulch Calculator by <a href="https://a2z.tools/embed/mulch-calculator" target="_blank" rel="nofollow noopener">A2Z Tools</a></p>
<script async src="https://a2z.tools/embed.js"></script>

Recommended. A small script (what it does) sizes the widget to fit its content, loads it lazily and keeps it isolated in its own frame. Works in WordPress (Custom HTML block), Squarespace, Webflow, Shopify, Blogger, React / Next.js and plain HTML - anywhere a <script> tag is allowed.

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How it works

The bed area - length x width, or pi x radius squared for a round bed - is multiplied by the depth. In imperial mode the answer is in cubic yards, the unit bulk mulch is delivered in, and in cubic feet for bagged product; metric mode gives cubic metres and litres. Bags are counted for 2 cu ft and 3 cu ft bags (common in the US) or 50 L and 75 L bags (common in the UK and Europe), rounded up. Depth guidance sits under the result: Penn State Extension advises a 2-4 inch layer of organic mulch and no more, and only 1-2 inches of finely shredded mulch; Colorado State Extension suggests 1-2 inches of compost worked 6 inches into a lawn area and 3-4 inches worked 8-12 inches into a new garden bed. A mulch or compost depth beyond those ranges triggers a caution. A quick check: 1,000 sq ft at 1 inch is 3.09 cubic yards, matching the extension rule of three yards per thousand square feet.

Calculation method

  • Volume = length x width x depth (round bed: pi x (diameter / 2)^2 x depth)
  • 1 yd3 = 27 cu ft; 1 m3 = 1,000 L; 1 cu ft = 28.3168 L
  • Bags = ceil(volume / bag volume) for 2 cu ft, 3 cu ft, 50 L or 75 L
  • Caution when depth exceeds 4 in for mulch (Penn State) or 4 in for compost (Colorado State)

Worked examples

Front-yard bed

Inputs: 10 x 10 ft; 3 in mulch; 2 cu ft bags

Result: 0.93 yd³ (25 cu ft); 13 bags

100 sq ft x 0.25 ft = 25 cu ft / 27 = 0.926 yd³; 25 / 2 = 12.5 -> 13.

Lawn compost top-up

Inputs: 50 x 20 ft; 1 in compost; 3 cu ft bags

Result: 3.09 yd³; 28 bags

1,000 sq ft x 1/12 ft = 83.3 cu ft = 3.09 yd³ - the 'three yards per thousand square feet' rule; 83.3 / 3 = 27.8 -> 28.

Metric shrub border

Inputs: 6 x 3 m; 7.5 cm mulch; 50 L bags

Result: 1.35 m³; 27 bags

18 m² x 0.075 m = 1.35 m³ = 1,350 L / 50 = 27.

Limitations

  • Volume only - no weight, because mulch and compost density changes greatly with moisture.
  • Bagged products settle and are sometimes compressed; the bag volume printed is used as-is.
  • Depth guidance is general extension advice, not a planting plan for a specific site.

Where publishers use it

  • Garden centres selling bagged and bulk bark, mulch and compost
  • Landscaping companies quoting bed refreshes by the yard
  • Allotment and vegetable-garden blogs preparing new beds
  • Tree-care articles on mulching rings around trunks
  • Municipal compost programmes telling residents how much to collect

Questions

How deep should mulch be?

Penn State Extension recommends a 2-4 inch layer of organic mulch and no more - less on poorly drained soil - and only 1-2 inches of fine or double-shredded mulch, which lets less air through. Keep it a few inches clear of trunks and stems.

How much area does a cubic yard of mulch cover?

A cubic yard is 27 cu ft: about 108 sq ft at 3 inches, 162 sq ft at 2 inches or 81 sq ft at 4 inches.

How many bags of mulch are in a yard?

13.5 bags of 2 cu ft or 9 bags of 3 cu ft. In metric, a cubic metre fills 20 bags of 50 L or 13.3 bags of 75 L.

How much compost should I add to a new bed?

Colorado State Extension suggests 3-4 inches of compost worked into the top 8-12 inches for a new vegetable or flower garden, and 1-2 inches worked into 6 inches before seeding a lawn.

How deep should topsoil be?

It depends on the job: a thin top-dressing to level a lawn, or several inches to build up a bed. No single figure applies, so the widget gives the volume for the depth you enter without a caution.

Is bulk or bagged cheaper?

Bulk is usually cheaper once you need more than a cubic yard or so, but needs a delivery and somewhere to tip it. Compare the bag count here with the supplier's bulk price per yard or m³.

Sources

  1. Mulching Landscape Trees - Penn State Extension . Apply a 2- to 4-inch layer of organic mulch and no more; use 1 to 2 inches of finely textured or double-shredded mulch.
  2. Choosing a Soil Amendment - Colorado State University Extension . Lawns: 1-2 in of compost incorporated 6 in; new gardens: 3-4 in incorporated 8-12 in; three cubic yards cover 1,000 sq ft about 1 inch deep.

Cite or recommend this tool

If you reference this tool in an article, course or documentation, these formats are ready to copy. They are optional - nothing is added to your site unless you paste it.

A2Z Tools Mulch Calculator
https://a2z.tools/embed/mulch-calculator

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