`M = Area( "a" , "b" , "c" , "d" , "D" ) * DP `

Enter a value for all fields

The Mulch Needed for an Irregular Area calculators computes the number                            AREA COVERED of regular 2 ft³ bags of wood-chip mulch needed to cover an area such as a field, garden or planter.  

INSTRUCTIONS: Choose your length units and enter the following:

• (a) Length of side a
• (b) Length of side b
• (c) Length of side c
• (d) Length of side d
• (D) Length of the diagonal (see diagram).
• (DP) The desired depth of mulch.

Mulch Needed for an Irregular Area(M): The calculator returns the number of standard bags of mulch, the volume of mulch in cubic yards and the area of the garden in square feet.  However, these can be automatically converted to compatible units via the pull-down menu.

The Math / Science

The calculator computes the area of the quadrilateral defined by the length of the four sides and the diagonal.  It then computes the volume by multiplying the area by the depth of mulch.  It then computes the number of bags by dividing the volume by the volume in a standard size bag.

Mulch Calculators:

• Mulch to Cover Area: Enter an area size (e.g. 45 square feet or 0.75 acres) and depth of mulch wanted, and see estimated amount of mulch needed.
• Mulch to Cover Circular Area:  Enter the diameter (D) of the circle and depth of mulch wanted, and see estimated amount of mulch needed.
• Mulch to Cover Rectangular Area: Enter the length (L) and width (W) of the area and depth of mulch wanted, and see estimated amount of mulch needed.
• Mulch to Cover Irregular Area: Enter the length of the four sides (a,b,c,d) and the diagonal (D) of an irregular area (see diagram) and the depth of mulch wanted, and see estimated amount of mulch needed.
• Mulch Cost Estimate: Enter the amount of mulch needed, choose a type of mulch and it will provide an estimate of the cost.
• Mulching With Straw (Irregular Area): Enter the length (L) and width (W) of the rectangular area and it will estimate the number of bales of straw needed to mulch the area with straw.
• Mulching With Straw (Area): Enter the area (acres, square feet) to see an estimate of the number of bales of straw needed to mulch the area with straw.
• Bulk vs Bag Price Comparison: Enter the bulk mulch and bag prices and volumes, and it tells you which is cheaper and by how much.
• Garden Area (Irregular):  Many gardens have four straight sides.  This calculator lets you enter the lengths of the sides (a,b,c,d) and the diagonal (D) to compute the square footage of the garden.

Mulch Pricing

You should always use the locally available pricing when computing your costs.  However, for your convenience a periodic survey is made on the Internet for mulch prices in the United States.  The most recent observations are as follows:

• Date: 12/27/21
• Store: Lowes
  • Red Mulch: 1.84 USD/ft³
  • Pine Mulch: 2.44 USD/ft³
  • Common Hardwood Mulch: 1.84 USD/ft³
  • Cedar Mulch: 1.83 USD/ft³
  • Rubber Mulch: 8.725 USD/ft³

See Also

• Greenhouse Calculator - Formulas and data for construction, heating and planting in a greenhouse or high-tunnel.
• Planter Calculator - Formulas for gardening with planters.
• Fencing Calculator - Formulas for farm fencing
• Electricians Calculator - Formulas for electrical wiring.
• Plumbers Calculator - Formulas for plumbing.
• Pole-barn and Shed Calculator - Formulas to assist in construction of a pole-barn, house or shed.