What soil mix is best for raised beds?

POPULAR OPTIONS: STANDARD MIX (60% topsoil, 30% compost, 10% perlite/potting soil) — balanced nutrition, drainage, structure; affordable. MEL'S MIX (1/3 vermiculite, 1/3 peat or coconut coir, 1/3 compost) — premium, perfect for intensive vegetable gardening; most expensive. GARDEN SOIL (pre-mixed) — convenient, $60-100/yard; ready to use. BUDGET MIX (70% topsoil, 30% compost) — functional, cheapest. For vegetables: invest in better mix. For flowers/perennials: less critical. Replenish annually with compost top-dressing for sustained productivity regardless of base mix.

How deep should a raised bed be?

Depends on plants: SALAD GREENS (lettuce, spinach, herbs) — 6-8 inches sufficient. MOST VEGETABLES (tomatoes, peppers, beans, squash) — 10-12 inches ideal. ROOT VEGETABLES (carrots, parsnips, potatoes, beets) — 18-24 inches optimal. SHRUBS/PERENNIALS — 18+ inches for established root systems. CONTAINERS/MIXED PLANTING — 12 inches typical compromise. Deeper is generally better (more root room, better drainage, drought-tolerance) but costs more. 12 inches is a common "good enough" depth for most home gardens. For raised beds over 18 inches deep: consider hugelkultur (bottom layers of wood/leaves) to save money on soil.

Should I fill a deep raised bed entirely with soil?

NO for beds 18+ inches deep — wasteful and expensive. HUGELKULTUR METHOD: Layer bottom 8-12 inches with logs, branches, leaves, cardboard, grass clippings, kitchen scraps. Top 10-12 inches with quality garden soil. BENEFITS: Saves 30-50% on soil cost. Long-term soil improvement as wood decomposes (5-10 years). Better water retention (sponge effect). Carbon sequestration. Reduces yard waste. DRAWBACKS: More setup labor. Bottom materials tie up nitrogen first year (add nitrogen-rich fertilizer like blood meal). Initial settling more dramatic. Top up annually as materials decompose. Plant roots grow into decomposing layers, accessing nutrients released over years. Hugelkultur enthusiasts swear by it; some traditional gardeners prefer straight soil for simplicity.

How much does it cost to fill a raised bed?

Cost depends on size, soil quality, sourcing. EXAMPLES (4 × 8 × 12" bed, 32 cubic feet): BAGGED standard mix: $130-$200. BULK garden soil: $90-$140 + delivery. PREMIUM mix (Mel's Mix bagged): $200-$300. HUGELKULTUR (top 12" only): $60-$100. MULTI-BED PROJECTS: Bulk delivery dramatically cheaper for 2+ beds. Single bed: bags often more convenient (avoid delivery fee). SAVINGS STRATEGIES: Source free compost from city programs. Use logs/branches from tree services for hugelkultur. Bulk delivery for multiple beds simultaneously. Hugelkultur reduces fill costs 30-50%. Most home gardeners can fill multiple beds for $200-$500 total with smart sourcing.

How should I prepare the ground under a raised bed?

OPTIONS: BARE GROUND — works for permanent beds; weeds can grow up through bottom. CARDBOARD LAYER — flatten boxes, lay over grass/weeds; smothers existing vegetation; decomposes within year; standard approach. NEWSPAPER — multiple layers; similar to cardboard. LANDSCAPE FABRIC — blocks weeds permanently but restricts root depth; less ideal for raised beds. NOTHING — works in fertile soil with low weed pressure. RECOMMENDED: cardboard layer for most situations. Cheap, effective, breathable, decomposes naturally. Lay cardboard, water lightly, then add soil. Smothers existing grass/weeds without herbicide. Worms thrive in this environment, improving soil structure over time.

Raised Bed Soil Calculator

Estimate the soil volume needed to fill your raised garden beds. Supports rectangular, L-shaped, and circular beds. Get results in cubic feet, cubic yards, and number of standard soil bags.

Raised garden beds — elevated planting boxes typically 6-24 inches deep — have transformed home gardening. Benefits include: superior drainage (water flows through), warmer soil (heats up faster in spring), easier access (less bending), better pest control (slugs/voles slower to reach), aesthetic appeal, and ability to garden in poor native soil conditions. Many gardeners can grow vegetables in raised beds where in-ground gardening would fail (heavy clay, contaminated soil, urban concrete, rocky ground). The trade-off: significant upfront investment in lumber/blocks ($50-$500 per bed) and soil fill ($30-$200 per bed depending on size).

Soil filling is where most raised bed projects encounter cost surprises. A typical 4×8×1 ft raised bed requires 32 cubic feet of soil. Bagged soil at $5-8 per cubic foot = $160-$256 per bed. Bulk soil at $40-$80 per cubic yard = $50-$100 per bed (plus delivery). For multiple beds, bulk dramatically more economical. Many builders use hybrid approaches: fill bottom 6-12 inches with cheap materials (logs, branches, leaves, cardboard — the "hugelkultur" method), top 12+ inches with quality garden soil mix. This both saves money and creates excellent soil over time as bottom materials decompose.

This calculator estimates soil volume needed for rectangular or circular raised beds, providing cubic feet, cubic yards, and standard bag count. Use it for: planning new beds, calculating soil for multiple beds, comparing fill strategies, or budget estimation. Important context: order 10-15% extra for settling (soil compresses ~15% in first season). Most vegetables benefit from 10-12+ inches of quality soil; root vegetables need 18+ inches. Fill bottom of deep beds with cheap materials (hugelkultur) to save money while still providing adequate growing depth. Match soil to use case: simple topsoil for filling; garden soil (topsoil + compost) for planting; premium organic mix for high-end vegetable beds.

Inputs

Bed Shape

Length (ft)

Width (ft)

Bed Height (inches)

Number of Beds

Price per Bag (1.5 cu ft) ($)

Results

Cubic Yards

1.19

Bags Needed (1.5 cu ft)

Estimated Cost

$132.00

Soil Breakdown

Detail	Value
Bed Shape	Rectangle
Bed Dimensions	8 x 4 ft
Bed Height	12 inches
Volume per Bed	32.0 cu ft
Number of Beds	1
Total Volume	32.0 cu ft
Cubic Yards	1.19
Bags (1.5 cu ft)	22
Bags (2 cu ft)	16
Estimated Cost	$132.00

Last updated: May 27, 2026

Formula

Raised bed soil calculation: For rectangular bed: Volume (cubic feet) = Length × Width × (Height / 12) For circular bed: Volume = π × (Diameter/2)² × (Height/12) Cubic Yards = Cubic Feet / 27 For multiple beds: Total = Per-bed volume × Number of beds Example: 4 × 8 ft rectangular bed, 12 inches deep. Volume: 4 × 8 × 1 = 32 cubic feet = 1.19 cubic yards Adding 15% for settling: 36.8 cubic feet (round up to 37) Standard soil mix (60% topsoil, 30% compost, 10% perlite): Topsoil needed: 32 × 0.60 = 19.2 cu ft Compost: 32 × 0.30 = 9.6 cu ft Perlite: 32 × 0.10 = 3.2 cu ft Bag count (1.5 cu ft bags): Topsoil: 19.2 / 1.5 = 13 bags Compost: 9.6 / 1.5 = 6.4 (7 bags) Perlite: 3.2 / 1.5 = 2.1 (3 bags) Total: 23 bags. At $6/bag: $138 per bed. Bulk alternative: 1.19 cubic yards of garden soil at $80/yard = $95 + delivery Common raised bed sizes and soil needs: | Size | Cubic Feet | Cubic Yards | |------|------------|-------------| | 2 × 4 × 6" | 4 | 0.15 | | 2 × 6 × 6" | 6 | 0.22 | | 4 × 4 × 12" | 16 | 0.59 | | 4 × 8 × 12" | 32 | 1.19 | | 4 × 12 × 12" | 48 | 1.78 | | 4 × 8 × 18" | 48 | 1.78 | | 4 × 8 × 24" | 64 | 2.37 | | 4-ft circle × 12" | 12.6 | 0.47 | Soil mix options: Mel's Mix (Square Foot Gardening): - 1/3 vermiculite - 1/3 peat moss or coconut coir - 1/3 compost (mixed varieties for diversity) - Best for intensive vegetable gardening - Most expensive but highest quality Standard raised bed mix: - 60% topsoil - 30% compost - 10% potting soil or perlite - Good balance of nutrition, drainage, structure - More affordable than Mel's Mix Budget mix: - 70% topsoil - 30% compost - Functional but less ideal drainage - Cheapest option Garden soil only (pre-mixed): - Convenient - $60-$100 per cubic yard - Already amended with compost - Easy ordering Cost comparison (4 × 8 × 1 ft bed = 32 cu ft): Bagged components separately: - Mel's Mix: $200-$300 - Standard mix: $130-$200 - Budget mix: $100-$160 Bulk delivered (1.5 cubic yards with 10% extra): - Premium garden soil: $90-$140 + $50 delivery - Standard garden soil: $60-$120 + $50 delivery - Topsoil + compost separately: $40-$100 + $50 delivery Hugelkultur method (deep beds): For 18-24" deep beds: - Bottom 8-12": logs, branches, leaves, cardboard, grass clippings - Top 10-12": quality garden soil Savings: - 4 × 8 × 24" full soil: 64 cu ft = ~$200-$400 - Hugelkultur same bed: ~$130-$200 (top 12" only) Benefits beyond cost: - Long-term improving soil (wood decomposes 5-10 years) - Water retention (sponge-like) - Carbon sequestration - Reduces waste Drawbacks: - More work to set up - Initial settling more dramatic - Wood ties up nitrogen first year (add extra nitrogen-rich fertilizer) Filling strategies for deep beds: Layer top-to-bottom: 1. Cardboard (decomposes; smothers weeds) 2. Logs and branches (4-6") 3. Leaves and small branches (4-6") 4. Grass clippings or kitchen scraps (2-4") 5. Compost (4-6") 6. Garden soil topping (10-12") Plant directly in top layer. Roots grow into deeper layers as established. Settling rate: - Year 1: 15-25% settling - Year 2-3: another 5-10% - Top up annually with compost What NOT to put in raised beds: - Treated lumber sawdust (chemicals leach) - Walnut wood (allelopathic, kills plants) - Cat litter (toxic to plants) - Meat/dairy scraps (attract pests) - Diseased plant material - Weeds with seeds (spread weeds) - Chemically treated grass clippings (herbicide residue) - Coal ash (heavy metals) Sourcing materials: Bagged soil: home improvement stores, nurseries Bulk soil: landscape supply yards (search "landscape supply" + your city) Compost: nurseries, garden centers, farms, municipalities (often free) Hugelkultur materials: tree services (free logs); leaves (own yard or municipality) Mulch: arborists, tree services (often free or cheap) Many homeowners can fill beds for under $50 if creative with material sourcing (free compost from city programs, free wood chips from tree services, salvaged materials). Raised bed sizing recommendations: Width: 3-4 feet maximum (so you can reach center without stepping in) Length: as long as desired (no functional limit) Depth: - Salad greens: 6-8 inches sufficient - Most vegetables: 10-12 inches ideal - Root vegetables (carrots, potatoes): 18-24 inches optimal - Permanent shrubs/perennials: 18+ inches Material options for bed walls: Cedar/redwood: rot-resistant, longest life (10-25 years), $$$ Pressure-treated lumber: long life but treated chemicals; some safe (modern); avoid older Composite lumber (recycled plastic/wood): rot-proof, 25+ year life, $$$ Concrete blocks: cheap, durable, easy stacking Recycled materials: pallets (untreated only), old tires, etc. Steel: rust-resistant powder coated; long life; sleek aesthetic Cost ranges per linear foot: Cedar: $5-10 Pressure-treated: $3-5 Composite: $8-15 Concrete block: $2-4 Recycled: free to cheap

How to use this calculator

Select bed shape (rectangle or circle).
Enter dimensions (length, width for rectangle; diameter for circle).
Enter height (typical 6-12" for shallow; 12-24" for deep).
Enter number of beds (calculator totals across all).
Enter price per bag (typical $5-$8 for 1.5 cu ft).
Review cubic feet, cubic yards, bag count, and cost.
For deep beds (18+ inches): consider hugelkultur to save money on bottom.
For multiple beds: compare bagged vs. bulk delivery (bulk usually cheaper).
For settling: order 10-15% extra.
For soil quality: invest in good quality for vegetables; less critical for flowers.
For ongoing maintenance: top up annually with compost (1-2 inches).
For pricing: $80-$140 typical for premium garden soil delivered.

Worked examples

Single small bed

4 × 4 × 12" raised bed (typical starter). Volume: 4 × 4 × 1 = 16 cubic feet = 0.59 cubic yards With 15% buffer: 18.4 cubic feet (round to 19) Bagged (1.5 cu ft at $6): 13 bags = $78 Bulk: probably not worth $50 delivery for small order Cost: ~$80 in bags Suitable for: salad greens, herbs, single tomato plant, mini-flower bed. Beginner-friendly size. Easy to manage, modest investment.

Three beds bulk delivery

Three 4 × 8 × 12" beds = 96 cubic feet total = 3.56 cubic yards With 15% buffer: 110 cubic feet = 4.1 cubic yards (order 4 yards) Bagged: 73 bags × $6 = $438 (substantial transport effort) Bulk: 4 yards × $80 + $80 delivery = $400 Bulk slightly cheaper AND dramatically easier. One truck delivery vs. 73 bags to transport. Bonus: extra material for future top-dressing. Bulk delivery breakpoint typically 2-3 cubic yards. Below that, bagged convenience often wins.

Deep bed with hugelkultur

4 × 8 × 24" bed (deep). Total volume: 64 cubic feet. OPTION 1: Full quality soil 64 cu ft = 2.4 cubic yards. Garden soil at $80/yard = $190 + $50 delivery = $240 OPTION 2: Hugelkultur (bottom 12" cheap materials, top 12" quality soil) Top 12" quality soil: 32 cu ft = 1.2 cubic yards = $100 + delivery Bottom 12": logs, branches, leaves, cardboard (free if creative; small cost otherwise) Total: ~$120 vs. $240 (50% savings) Plus benefits: long-term soil improvement as wood decomposes; better water retention; carbon sequestration; reduced waste. For deep beds: hugelkultur dramatic savings without sacrificing growing quality. Top 12" of quality soil handles 95% of plant roots. Drawback: more setup labor and slightly different first-year considerations.

When to use this calculator

Use this calculator for planning new raised beds, calculating soil needs for multiple beds, comparing filling strategies, or budgeting raised bed projects.

Pair with soil-calculator, mulch-calculator, and compost-calculator.

Important raised bed considerations:

1. **Order 10-15% extra for settling.** Soil compresses ~15% first season.

2. **Hugelkultur saves on deep beds.** Bottom layers of free materials, top quality soil.

3. **Bulk delivery economical at 2+ yards.** Below that, bags often easier.

4. **Match soil mix to crops.** Vegetables: garden soil with compost. Flowers: standard mix. Containers: separate potting mix.

5. **Top up annually.** Compost mulch 1-2" replaces depleted nutrients.

6. **Plan bed width for reach.** 3-4 ft maximum so you can reach center without stepping in.

7. **Match depth to plants.** Salad greens 6"; most vegetables 10-12"; root vegetables 18-24".

8. **Use cedar or pressure-treated for walls.** Modern PT lumber considered safe for gardens.

9. **Don't use older treated lumber.** Pre-2004 CCA-treated had arsenic.

10. **Free materials available.** Free compost (city programs), free wood chips (arborists), salvaged lumber.

11. **Consider raised bed location.** 6+ hours sun for vegetables; near water source; level ground.

12. **Annual replenishment needed.** Soil depletes; add compost yearly for sustained productivity.

Common mistakes to avoid

Underestimating soil quantity. Cubic feet seems small; actual volume substantial.
Skipping settling buffer. Soil compresses 15%; bed appears too shallow first season.
Using only bagged soil for large projects. Bulk delivery dramatically cheaper.
Filling deep beds entirely with quality soil. Hugelkultur saves significant money.
Choosing too-wide beds. 4 ft maximum so center is reachable without stepping in.
Not topping up annually. Soil depletes; compost mulch maintains productivity.

Frequently Asked Questions

Sources & further reading

Vegetable Gardening Resources — University of Minnesota Extension
Square Foot Gardening — Square Foot Gardening Foundation
USDA Gardening Resources — U.S. Department of Agriculture

SponsoredShop Top Deals on AmazonSupport CalcMountain — browse top-rated products at no extra cost to you.