Raised Bed Soil Calculator
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GardenSays
Buy 24 bags of raised bed soil mix (1.5 cu ft) — or 1.3 cubic yards in bulk.
- Needed
- 32 cu ft
- Buy
- 24 × 1.5 cu ft
- Bulk
- 1.3 cu yd
Your 8×4 ft needs 32 cu ft of raised bed soil mix (906.1 litres); with the 10% settling allowance, plan for 35.2 cu ft (996.8 L). At 1.3 cubic yards, get a bulk quote too and compare it against 24 bags with the delivery fee included — prices vary a lot by region.
Do this this week
- 1.Buy 24 × 1.5 cu ft bags — or 1.3 yd³ in bulk
- 2.Get a bulk quote too, and compare it with the delivery fee included
- 3.Fill level and even — the math assumes interior dimensions and uniform depth
Typical estimate · 1 verified source · Checked 2026-07-15 · How we decide
Why
One common approach from extension guides: a topsoil-plus-compost blend (roughly half-to-60% topsoil, the rest mostly compost, with some aeration material — our estimate of a typical published range). Mixes vary; bagged 'raised bed mix' works too.
- The exact math says 21.3 bags — the recommendation rounds up and adds 10% because soil settles and measurements are never perfect.
- Bagged product typically costs 2-3× bulk per cubic foot once you pass about one cubic yard (our estimate from typical retail pricing).
When this doesn't apply
- Material settles: a raised bed fill can drop 10-20% in the first season — that's what the buffer covers.
- L-shaped or irregular areas: split into rectangles, calculate each, and add the results (multi-area support is coming).
- Assumptions: interior dimensions, uniform depth, level fill; cost excludes tax and delivery.
How this was calculated
- 1. Area (rectangle)32 sq ft
8 ft × 4 ft
- 2. Volume32 cu ft
32 sq ft × 12/12 ft deep
- 3. Purchase buffer× 1.1 → 35.2 cu ftGardenSays estimate
Soil settles and beds are never perfectly measured — a 10% allowance avoids a second trip (our estimate; adjustable above)
- 4. In bags24 bagsCalculated result
35.2 cu ft ÷ 1.5 cu ft per bag = 23.5, rounded up to whole bags
- 5. In bulk1.3 cu ydCalculated result
35.2 cu ft ÷ 27 (bulk is sold by the cubic yard)
Data sources
- University of Minnesota Extension — Raised bed gardens (checked 2026-07-15)
What changes this answer
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Every change updates the answer, the math, the weekly steps and the share link instantly.
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