How-To

How to Calculate Mulch for Your Beds

How to Calculate Mulch for Your Beds | Erickson’s Landscape Supply

Nothing’s worse than running out of mulch halfway through a Saturday project—or ending up with a mountain of extra material baking in your driveway. We’ve seen both happen more times than we can count.

Here’s the good news: figuring out how much mulch you need isn’t complicated. One simple formula, a tape measure, and ten minutes is all it takes. We’ll walk you through it step by step.

The Only Formula You Need
Length (ft) × Width (ft) × Depth (in) ÷ 324 = Cubic Yards
Why 324? It converts square feet and inches into cubic yards. You don’t need to memorize why—just use it.

Mulch is sold by the cubic yard at our yard (and at most landscape suppliers). So that’s the number you’re after. Let’s break down how to get there.


1

Measure Your Beds

Grab a tape measure and head outside. Measure each bed separately—you’ll add them together at the end. Don’t try to do it from memory; go out and measure.

Rectangular Beds (The Easy One)

Length times width. That’s it.

Example

A bed that’s 20 ft long × 4 ft wide = 80 square feet

Circular Beds (Around Trees)

Measure from the center of the circle to the edge—that’s your radius. Then:

Radius × Radius × 3.14 = Square Feet
Example

A mulch ring with a 4-foot radius: 4 × 4 × 3.14 = 50 sq ft

Odd-Shaped or Curvy Beds

Break the bed into rough rectangles, measure each section, and add them up. You’re estimating here, not building a rocket. A little generous is fine—that’s why we round up at the end.

Pro Tip

Write your measurements on your phone as you go. It’s easy to forget which bed was which once you’re back inside doing the math.

2

Decide How Deep to Go

🌿 Image: Cross-section of a mulch bed showing proper 3-inch depth layer

Mulch depth makes a big difference in how much you order. Here’s what we recommend based on your situation:

Situation Recommended Depth Notes
Fresh beds, no existing mulch 3 inches The sweet spot for weed suppression and moisture
Refreshing last year’s mulch 1–2 inches Top it off; restore color and fill thin spots
Heavy weed area, starting fresh 3–4 inches Extra depth suppresses persistent weeds better
Slopes 3–4 inches Mulch shifts downhill over time
⚠ Important

Don’t go deeper than 4 inches. Excessive mulch can suffocate plant roots, hold too much moisture, and actually create a surface where weeds grow right on top. More isn’t better here.

3

Do the Math

Now plug your numbers into the formula. We’ll do a few examples so you see how it works.

Example 1 — Simple Rectangular Bed

Bed size: 20 ft × 4 ft at 3 inches deep

20 × 4 × 3 ÷ 324 = 0.74 cubic yards

Example 2 — Mulch Ring Around a Tree

Circular bed with a 4-foot radius at 3 inches deep

50 sq ft × 3 ÷ 324 = 0.46 cubic yards

Example 3 — Multiple Beds, Full Refresh

400 total square feet of beds at 2 inches deep

400 × 2 ÷ 324 = 2.47 cubic yards

If you don’t want to do the math yourself, we’ve got a volume calculator on our website—plug in your dimensions and it figures it out for you. Or just call us and read off your measurements; we’re happy to help.

4

Round Up (Just a Little)

Always add about 10% to your calculated amount. Here’s why it matters:

  • Beds are almost never perfect rectangles—curves and corners add up
  • Mulch compresses and settles after you spread it
  • Having a small pile left over is useful for bare spots later in the season
  • Running out mid-project means waiting on another delivery or making another trip
Quick Rule

If the formula says 3 yards, order 3.3 or round up to 3.5. That cushion is worth it every time.


Quick Reference: How Far Will One Yard Go?

Don’t want to do the math at all? Here’s a fast reference for how much area a single cubic yard of mulch covers at different depths:

Depth Coverage Per Cubic Yard Good For
2 inches 162 square feet Light refresh on existing beds
3 inches 108 square feet New beds, full refresh
4 inches 81 square feet Heavy weed areas, slopes

So if you have 300 square feet of beds and want 3-inch depth: 300 ÷ 108 = about 2.8 cubic yards. Round up to 3.


Pickup or Delivery?

Once you know how much you need, you’ve got two ways to get it home.

Pickup at Our Yard

If you have a truck or trailer, you can load up and go. A standard full-size pickup holds about 2–3 cubic yards depending on the truck and how high you load it. Just remember—wet mulch is heavier than dry. Don’t overload your truck.

Delivery to Your Door

We deliver everything from a half yard to 70-yard semi loads. For most homeowners, delivery makes sense when you need more than 2–3 yards, don’t have a truck, or just don’t want the mess in your vehicle. We’ll drop it right where you need it.

What Works for Most Homeowners

If you’re mulching 400+ square feet of beds at 3 inches deep, you’re looking at 3.5+ yards. That’s a lot of trips with a pickup. Delivery is usually worth it at that point.


Which Mulch Should You Choose?

Once you know how much you need, the next question is which variety. We manufacture our mulch on-site in Kansasville from whole trees—not just bark—which means richer color and longer-lasting coverage. We carry 12 varieties from economy hardwood at $24/yard up to premium cedar and hemlock for a more refined look.

  • Premium Black, Brown, Red, Gold, Caramel: Deep color, whole-tree durability—$36/yard
  • Eastern White Cedar: Natural scent, beautiful light color—$52.50/yard
  • Hemlock: Rich reddish-brown, slow to fade—$56/yard
  • Economy options: Great coverage for larger projects on a budget—from $24/yard

Stop by our display yard and see them side by side. Color looks different in photos than it does in person—especially once it’s down in your beds.

Ready to Order?

Got your numbers? Give us a call and we’ll get you squared away—or use our volume calculator if you still want to double-check.

Common Questions

Do I need to remove old mulch before adding new?

Usually no. If your existing mulch is in reasonable shape, just top it off with 1–2 inches. If it’s heavily decomposed, matted, or piled way too thick, rake some out first—but that’s the exception, not the rule.

What about plants in my beds?

Measure the whole bed including where your plants are. Mulch goes around plants, not over them, and the area they take up is absorbed in your 10% cushion.

How do I handle beds on a slope?

Slopes don’t change the math, but do go a bit thicker—3 to 4 inches—since some mulch will shift downhill over the season.

Still not sure?

Stop by and tell us the rough dimensions of your beds. We do this every day. We’d rather spend five minutes with you now than have you run short on a Saturday afternoon.


Ready to Order? Call Us