Mulch Calculator
Work out how much mulch a bed needs in cubic yards and bags, from its size and how deep you want to go.
Measure the bed, pick a depth, and this gives you cubic yards for a bulk delivery and bag count for the garden centre.
Your details
The long side of the bed.
The short side of the bed.
2-3 inches for most beds, 3-4 to suppress weeds.
Check the bag — 2 cu ft is the most common.
Result
What to order for a bulk delivery.
- Cubic feetThe same volume, before converting to yards.
- 50
- Bags to buyRounded up — you cannot buy part of a bag.
- 25
- Bed areaSquare feet of ground being covered.
- 200
About this tool
How Much Mulch Do I Need?Mulch is sold by volume, so the answer is length times width times depth. Here's the arithmetic, the conversions, and where people get it wrong.
Free download
Mulch & Bed Measuring SheetMeasure every bed in one walk round the garden, then total it up. Same conversions this calculator uses.
Free, no email required — print it or save it as a PDF.
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Mulch Calculator infographicThe key numbers as one image — free to save, share, or embed on your own site with credit.
How this is calculated
Mulch is sold by volume, so the whole job is length x width x depth. Depth is entered in inches and divided by 12 to put it in feet before multiplying. A cubic yard is 27 cubic feet, by definition — that is the conversion used for the bulk figure, not an estimate. Bag count is the total cubic feet divided by the size of the bag you buy, rounded up. Bag size is an input because it varies: 2 cubic feet is the most common in the US, but 1.5 and 3 cubic foot bags are both sold. The calculator assumes a rectangular bed. For an irregular shape, split it into rectangles, run each one, and add the results.
Common questions
- How deep should mulch be?
- Two to three inches suits most planted beds. Three to four inches holds weeds down better, but going much past four can keep water from reaching the soil and hold damp against stems.
- Should I buy bags or bulk?
- Compare on volume. A cubic yard is 13.5 bags at 2 cubic feet each, so once you are past roughly ten or fifteen bags, bulk is usually cheaper and always less carrying.
- Do I need to remove the old mulch first?
- Usually not. Rake what is there to break up any crust, then top up to your target depth rather than adding a fresh full layer on top of the old one.
- My bed is not a rectangle. What now?
- Split it into rectangles, run the calculator for each, and add the cubic yards together. Slight overestimates are fine — mulch settles.
Take it further with AI
Copy this into ChatGPT or Claude with your own numbers filled in. It hands over the figures this calculator worked out, so the answer is built on real arithmetic instead of a guess.
I used the Mulch Calculator at https://www.bfcbrilliance.com/tools/mulch-calculator.
What I entered:
- Bed length (ft): ___
- Bed width (ft): ___
- Mulch depth (in): ___
- Bag size (cu ft): ___
What it calculated:
- Cubic yards: ___
- Cubic feet: ___
- Bags to buy: ___
- Bed area: ___
Use those figures as given — they are already worked out, so please don't recalculate or estimate your own. Help me turn them into a plan: what to buy or do, in what order, roughly what it should cost, and the mistakes people most often make with this job.Last updated
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Part of a bigger job
How to Mulch and Edge a BedMulch depth, topsoil settling and the edging most people over-order — three quick calculations that decide how a bed looks all season.
Walks through all 3 mulch & ground cover tools in order.