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Mulch Bed Calculator · Free calculator

16x20 Mulch Bed Calculator

Mulching a 16' × 20' bed (320 sq ft) 3" deep takes 3.11 cubic yards — 42 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 16x20.

Quick answer

3" deep (standard)
3.11 yd³
2 cu ft bags @ 3"
42
2 cu ft bags @ 2"
28
Bags cost @ 3"
$168
Bulk cost @ 3"
$130
Edging
72 LF

▍Mulch Calculator

Material
ft
in
ft
in
in
Waste Factor
$
L = 20' 0"W = 16' 0"D = 3"
Cubic Yards
3.11yd³
incl. 5% waste · Bulk delivery: order 3.25 yd³
Cubic Feet
84.00ft³
Area
320.0sq ft
Weight
0.93tons
Weight
1,867lbs
Mulch bags needed
  • 2 cu ft bag (2 ft³ yield)42

Mulch for a 16x20 bed by depth

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

DepthUseCubic yards2 cu ft bagsBags $Bulk $Weight
2"Refresh existing bed2.07 yd³28$112$901,244 lbs
3"Standard (weed control)3.11 yd³42$168$1301,867 lbs
4"New bed / heavy weeds4.15 yd³56$224$1702,489 lbs

Bed prep for 16x20

ItemQuantityNotes
Landscape fabric (3' × 50' rolls)3352 sq ft incl. 10% overlap
Bed edging (20' sections)472 LF perimeter
Fabric staples36~1 per 9 sq ft
Pickup loads (≈2.5 yd³)2bulk mulch @ 3"

How the math works

  1. Area: 20 ft × 16 ft = 320 sq ft
  2. Volume @ 3": 320 × (3 ÷ 12) = 80.00 cu ft
  3. Add 5%: 80.00 × 1.05 = 84.00 cu ft
  4. Cubic yards: 84.00 ÷ 27 = 3.11 yd³
  5. Bags: 84.00 ÷ 2 cu ft = 42 bags

Trade pro tips

  • 3.11 yd³ at 3" — bulk delivery will be cheaper than bags.
  • 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 16x20 area?

At 3" deep, 42 bags of 2 cu ft mulch. At 2": 28 bags. At 4": 56 bags. All include 5% extra for 320 sq ft.

How many yards of mulch for 16x20?

2": 2.07 yd³; 3": 3.11 yd³; 4": 4.15 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 16x20 bed?

At 3": about $168 in bags or $130 in bulk before delivery. Bulk is usually cheaper at this size.

How much does the mulch for 16x20 weigh?

About 1,867 lbs at 3" (mulch runs 400–800 lbs per yd³ depending on moisture). That's 1.2 half-ton pickup loads of bulk mulch.