Raised Garden Bed Soil Calculator – Growing Medium Estimator
Calculate soil volume needed for raised garden beds
Table of Contents
How to Use
- Select your bed shape (rectangular or circular)
- Enter bed dimensions and depth
- Specify number of beds to fill
- Optionally enter bag size for bag count
- Click calculate to get soil volume needed
Raised Garden Bed Soil Basics
Raised garden beds require quality soil or growing medium to support healthy plant growth. The amount needed depends on the bed dimensions and how many beds you're filling.
Most raised beds are 6-12 inches deep for vegetables and herbs, though root vegetables like carrots may benefit from 12-18 inches of depth.
Recommended Soil Mixes
A good raised bed soil mix typically consists of:
- 40% topsoil or garden soil
- 40% compost (for nutrients and moisture retention)
- 20% aeration material (perlite, vermiculite, or coconut coir)
- Optional: slow-release organic fertilizer
Pre-mixed raised bed soil is also available at garden centers, often labeled as 'raised bed mix' or 'garden bed soil'.
How to Calculate Soil Volume
The volume calculation depends on your bed shape:
- Rectangular beds: Length × Width × Depth
- Circular beds: π × (Diameter/2)² × Depth
Multiply the result by the number of beds to get your total volume needed.
Purchasing Soil Tips
- Bagged soil is convenient for small projects (under 1 cubic yard)
- Bulk soil delivery is more economical for large projects (over 1-2 cubic yards)
- Standard bag sizes are 1, 1.5, or 2 cubic feet
- Order 10-15% extra to account for settling
- Consider mixing your own soil to save money on large projects
- Check bag labels carefully - some contain fertilizers, others don't
Frequently Asked Questions
- How deep should my raised garden bed be?
- Most vegetables and herbs thrive in 6-12 inches of soil. Root vegetables like carrots and parsnips benefit from 12-18 inches. If your bed sits on grass or soil, plant roots can extend deeper, so 6-8 inches may suffice.
- Should I buy bagged soil or bulk soil?
- For small projects under 1 cubic yard (27 cubic feet), bagged soil is convenient. For larger projects, bulk soil delivery is more economical, typically costing 30-50% less per cubic yard.
- Can I use regular garden soil in raised beds?
- Regular garden soil can be heavy and may compact in raised beds. It's best to use a mix that includes compost for nutrients and an aeration amendment like perlite or coconut coir for drainage and root growth.
- How many bags of soil do I need?
- This depends on your bag size. Standard bags are 1, 1.5, or 2 cubic feet. Use this calculator with your bag size entered to get an accurate count. Always round up and consider buying 10-15% extra.
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