Did You Know? Mulch Calculator


Today’s “Did You Know” post will be about figuring out the amount of mulch you need for a given area…it’s a mulch calculator, if you will. Since the leaves have fallen, a lot of people will be applying their winter layer of mulch and putting their gardens to bed for the winter. There seems to be confusion about how much mulch it takes to cover a given area so I thought that I would give you some helpful conversions.


The first thing you’ll need to do is measure the area. If the bed is a square or rectangle, multiply the length times the width to come up with the square footage (ft2). Example: your bed measures 20′ long by 6.5′ wide. 20 × 6.5 = 130 ft2.

If it’s more of a triangular area, try to figure the area as if it’s a square or rectangle and then divide it in half. Remember, you’re not in geometry class, you’re just trying to come up with the square footage.

If you’re working with a circle, measure the radius (that’s from the center of the circle to the outside of the circle) and use this formula: Area = ∏ × r2. In case you forgot, ∏ (pi) = 3.14. If you have a 6′ wide circle then the radius is 3′. 3.14 x 32 = 28.26 ft2.


OK…you’ve determined your square footage so now how do you figure out how much mulch you’ll need? This is the simplest part…just remember these simple figures:

Assuming that you are using cubic yards (yd3) of mulch:

  • at 2″ thick, 1 yd3 of mulch will cover 180 ft2
  • at 3″ thick, it will cover 110 ft2
  • at 4″ thick, it will cover 80 ft2


So in the above example for the 130 ft2 bed, you would need 1.18 yd3 of mulch if you were applying the mulch at 3″ deep. See my mulch volcano article for some helpful hints on proper mulching depth.

If you are working with bagged mulch, it is often sold in 2 ft3 bags. For what it’s worth, there are 27 ft3 in a cubic yard of mulch. With that being said, here’s how much each 2 ft3 bag will cover:

  • at 2″ thick, each bag will cover 12 ft2
  • at 3″ thick, each bag will cover 8 ft2
  • at 4″ thick, each bag will cover 6 ft2


Knowing that there are 27 ft3 of mulch in a yard can also come in handy when comparing prices between bagged mulch and bulk mulch that is sold by the yard.

I hope this has been a helpful “Did You Know” post…let me know your thoughts or questions at stacey@midatlanticgardening.com. I’m really enjoying the e-mails I’m receiving…please keep them coming! Happy mulching!

December 5, 2011Permalink Leave a comment

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