Grow a Garden Calculator

by

Reviewed by: David Chen, Horticultural Specialist (HortS).

This calculator utilizes standard horticultural formulas for accurate garden planning and resource estimation.

The Grow a Garden Calculator is an essential tool for any successful planting project. It helps determine the necessary volume of soil, mulch, or compost required for your garden beds, saving you time and preventing costly over- or under-ordering of materials. Simply input your bed dimensions to get started.

Grow a Garden Calculator: Soil Volume

Calculated Volume: —

Grow a Garden Calculator Formula

This calculator determines the required material volume (in Cubic Feet) based on the simple geometry of a rectangular prism, with an additional step to convert depth from inches to feet.

V = L $\times$ W $\times$ (D / 12)
T = V $\times$ C (If Cost is provided)

Formula Sources: Gardening Know How – Soil Volume, University of Minnesota Extension

Variables

  • Garden Bed Length (L): The long side dimension of your rectangular garden in feet.
  • Garden Bed Width (W): The short side dimension of your garden bed in feet.
  • Desired Soil Depth (D): The required vertical depth of the material, measured in inches. This is divided by 12 to convert it to feet for the volume calculation.
  • Cost per Cubic Foot (C): The price you pay for your chosen material (soil, compost, or mulch) per cubic foot.

Related Calculators

Streamline your gardening projects with these specialized calculators:

What is Soil Volume Calculation?

Calculating soil volume is the foundational step for building raised garden beds or filling large containers. It’s critical because soil materials are typically sold by volume (cubic feet or cubic yards), and accurately determining your needs prevents ordering too much—leading to wasted material—or too little—requiring extra trips and delays.

Unlike flat area measurements, volume incorporates the third dimension (depth). For a garden bed, this depth is often set between 8 to 12 inches to allow ample room for root growth and drainage. Precision in this calculation is key to budgeting and project execution.

How to Calculate Soil Volume (Example)

  1. Measure Dimensions: A gardener has a bed that is 10 feet long (L) and 3 feet wide (W). They need 8 inches (D) of new soil.
  2. Convert Depth to Feet: Divide the depth in inches by 12: $8 \div 12 = 0.6667$ feet.
  3. Calculate Volume: Multiply the three dimensions: $10 \text{ ft} \times 3 \text{ ft} \times 0.6667 \text{ ft} = 20.00$ cubic feet.
  4. Estimate Cost (Assuming $2.00 per cubic foot): $20.00 \times \$2.00 = \$40.00$.
  5. Review and Order: The gardener requires 20 cubic feet of soil, costing approximately $40.00, before taxes and delivery.

Frequently Asked Questions (FAQ)

1. Why do I need to convert inches to feet for the calculation?
You must convert the depth (usually in inches) to feet because the length and width are also in feet. To get the final volume in cubic feet, all three measurements must be in the same unit.

2. Should I round up or down when ordering soil?
It is always recommended to round up the final volume (usually to the nearest half-cubic yard) to account for settling, compaction, and slight measurement errors. It’s better to have a small amount extra than to run short.

3. Can this calculator be used for circular or irregular beds?
This specific calculator is designed for rectangular beds. For circular beds, you would need a different formula (Volume = $\pi \times R^2 \times D$), and for irregular shapes, it’s best to divide the area into smaller, measurable rectangles or squares.

4. Does the calculated volume account for soil compaction?
No, the calculated volume is the required volume of loose material. Soil, especially topsoil and compost, will settle and compact over time (usually 10-20%). You should manually add an extra percentage to the result before ordering to compensate for this.

V}

Leave a Comment