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Mulch Bed Calculator · Free calculator

12x20 Mulch Bed Calculator

Mulching a 12' × 20' bed (240 sq ft) 3" deep takes 2.33 cubic yards — 32 bags of 2 cu ft mulch with 5% extra. Here's 2", 3" and 4" depth, bag vs bulk cost and the fabric and edging for 12x20.

Quick answer

3" deep (standard)
2.33 yd³
2 cu ft bags @ 3"
32
2 cu ft bags @ 2"
21
Bags cost @ 3"
$128
Bulk cost @ 3"
$100
Edging
64 LF

▍Mulch Calculator

Material
ft
in
ft
in
in
Waste Factor
$
L = 20' 0"W = 12' 0"D = 3"
Cubic Yards
2.33yd³
incl. 5% waste · Bulk delivery: order 2.50 yd³
Cubic Feet
63.00ft³
Area
240.0sq ft
Weight
0.70tons
Weight
1,400lbs
Mulch bags needed
  • 2 cu ft bag (2 ft³ yield)32

Mulch for a 12x20 bed by depth

240 sq ft, 5% extra. Bags ~$4.00 (2 cu ft), bulk ~$40/yd³.

DepthUseCubic yards2 cu ft bagsBags $Bulk $Weight
2"Refresh existing bed1.56 yd³21$84$70933 lbs
3"Standard (weed control)2.33 yd³32$128$1001,400 lbs
4"New bed / heavy weeds3.11 yd³42$168$1301,867 lbs

Bed prep for 12x20

ItemQuantityNotes
Landscape fabric (3' × 50' rolls)2264 sq ft incl. 10% overlap
Bed edging (20' sections)464 LF perimeter
Fabric staples27~1 per 9 sq ft
Pickup loads (≈2.5 yd³)1bulk mulch @ 3"

How the math works

  1. Area: 20 ft × 12 ft = 240 sq ft
  2. Volume @ 3": 240 × (3 ÷ 12) = 60.00 cu ft
  3. Add 5%: 60.00 × 1.05 = 63.00 cu ft
  4. Cubic yards: 63.00 ÷ 27 = 2.33 yd³
  5. Bags: 63.00 ÷ 2 cu ft = 32 bags

Trade pro tips

  • 2.33 yd³ at 3" — bags are easier than bulk for this size.
  • Keep mulch 2"–3" away from trunks and siding — no "mulch volcanoes".
  • Refreshing an existing bed usually only needs 1"–2" on top.
  • One cubic yard of bulk mulch = 13.5 two-cu-ft bags.
  • A half-ton pickup carries 2–3 yd³ of mulch; a full-size bed with sides can take about 3.

Frequently asked questions

How many bags of mulch do I need for a 12x20 area?

At 3" deep, 32 bags of 2 cu ft mulch. At 2": 21 bags. At 4": 42 bags. All include 5% extra for 240 sq ft.

How many yards of mulch for 12x20?

2": 1.56 yd³; 3": 2.33 yd³; 4": 3.11 yd³. Bulk mulch is sold by the cubic yard; 1 yd³ = 13.5 bags of 2 cu ft.

How much does it cost to mulch a 12x20 bed?

At 3": about $128 in bags or $100 in bulk before delivery. Bags are usually simpler at this size.

How much does the mulch for 12x20 weigh?

About 1,400 lbs at 3" (mulch runs 400–800 lbs per yd³ depending on moisture). That's 0.9 half-ton pickup loads of bulk mulch.