Raised Bed Soil Calculator

Estimate how much soil you need to fill a raised garden bed in cubic feet, cubic yards, bags, and simple soil mix amounts.

Enter Your Raised Bed Size


Presets are common examples. Measure your actual bed before buying soil.


Choose the closest shape for your raised bed.


Use the depth you want to fill with soil, not always the full wall height.


Measure the inside length of the bed.


Measure the inside width of the bed.


Use 0 for an empty bed. Enter existing soil depth if topping off.


Adds extra for settling, uneven fill, and bag variation.


Most bagged soil is sold by cubic feet.


Mix ratios are planning examples, not a universal gardening rule.


Optional. Used for bagged soil cost.


Optional. Used for bulk soil cost comparison.


Optional delivery, rental, or minimum-order fee.


Your Results

Cubic feet

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Enter values and calculate.

Cubic yards

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Useful for bulk soil orders.

Bags needed

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Rounded up to whole bags.

Cost estimate

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Uses your price inputs.

Soil mix estimate will appear here after calculation.
This calculator gives a planning estimate only. Real soil needs can vary because of settling, compaction, bag fill differences, old soil depth, and bed shape.

How to Use This Raised Bed Soil Calculator

Enter the inside dimensions of your raised bed, the depth you want to fill, and any existing soil already in the bed. The calculator estimates cubic feet, cubic yards, bags, and optional cost.

For new raised beds, use an existing fill depth of 0 inches. For topping off an older bed, enter the soil already in place so you only estimate the amount needed to finish filling it.

Formula Used

Area = length × width
Fill depth = target depth − existing fill depth
Fill depth in feet = fill depth in inches ÷ 12
Cubic feet = area × fill depth in feet
Adjusted cubic feet = cubic feet × (1 + buffer %)
Cubic yards = adjusted cubic feet ÷ 27
Bags needed = adjusted cubic feet ÷ bag size

Example Calculation

A 4 ft × 8 ft raised bed filled 12 inches deep has:

4 × 8 = 32 square feet
12 inches ÷ 12 = 1 foot deep
32 × 1 = 32 cubic feet
32 ÷ 27 = 1.19 cubic yards

With a 10% buffer, that becomes about 35.2 cubic feet, or 18 bags if each bag contains 2 cubic feet.

Common Raised Bed Soil Mistakes

  • Measuring the outside of the bed instead of the inside dimensions.
  • Forgetting that soil settles after watering and planting.
  • Buying the exact calculated amount with no extra buffer.
  • Assuming every bag contains the exact same usable volume once fluffed or compacted.
  • Filling a very deep bed entirely with expensive bagged soil when bulk soil may be more practical.
  • Using a generic mix without considering the plants, drainage, compost level, and local conditions.

Important Planning Note

Use this calculator as a planning tool only. Soil needs depend on the bed size, old soil depth, settling, compost content, drainage, plant type, and local growing conditions.

For edible gardens, check that the materials used in or around the raised bed are appropriate for gardening. Avoid questionable treated wood, contaminated fill, or unknown soil sources.