Soil Calculator — Topsoil, Fill Dirt, Garden Soil Volume

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Length

Width

Depth

Soil type

Bulk price (per yd³)

$/yd³

Bag price (1 ft³)

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You need

3.70 cubic yards

= 100.00 ft³ · 4.81 tons · ≈ 100 bags (1 ft³)

Bulk: $111 · Bagged: $400 (save $289 with bulk)

How to Calculate Soil Quantity

Soil quantity calculation is straightforward but trips up beginners because of the mixed-unit problem: areas are typically in square feet (or square yards), depths are in inches, and suppliers sell in cubic yards. The math handles all that for you, but understanding the formula helps verify the result.

Cubic yards = (Area in sq ft × Depth in inches) ÷ 324
Weight (tons) = Cubic yards × Density factor
Bags (1 ft³) = Cubic yards × 27

The factor 324 combines 12 (inches per foot) × 27 (cubic feet per cubic yard) into a single divisor. Density depends on soil type: 1.30 t/yd³ for dry topsoil, 1.45 for fill dirt, 0.80 for light garden mixes, up to 1.60 for clay soil.

Worked example: filling a 4x8 raised bed

For a standard 4 ft × 8 ft raised garden bed at 12 inches deep:

Volume: (4 × 8 × 12) ÷ 324 = 1.19 cubic yards
In cubic feet: 32 ft³
In bags (1 ft³): 32 bags
Weight (garden mix at 0.80 t/yd³): 0.95 tons (≈ 1,900 lb)
Bulk cost (at $35/yd³): $42
Bagged cost (at $5/bag): $160
Savings with bulk: $118

Always order 10-20% extra for settling

Fresh soil compresses significantly over the first 6 months as air gaps close and organic matter decomposes. For raised beds, overfill by 2-3 inches initially or plan to top up after a season. For lawn installation, return at 4-6 weeks to level any depressions before final seeding.

Choosing the Right Type of Soil

Not all soil is the same — and using the wrong type ruins projects. Here's the practical breakdown of soil types you'll encounter at any landscape supplier.

Topsoil

The dark, organic-rich layer of natural soil (the top 4-8 inches in a healthy field). Used for lawn installation, garden bed prep, and grade adjustment where you want plants to grow. Density: 1.30 t/yd³ dry, 1.50 wet. Cost: $20-50/yd³ bulk. Best quality is "screened topsoil" — sifted to remove rocks and debris.

Fill dirt

Subsoil from below the topsoil layer — heavier, denser, low in organic matter. Used for raising grade, filling holes, building up areas before final topsoil layer. Will compact well but plants won't thrive in it directly. Density: 1.45 t/yd³. Cost: $15-30/yd³ — cheapest soil category. Often available free from construction sites if you can haul.

Garden soil (planting mix)

Topsoil pre-mixed with compost, peat moss, and sometimes vermiculite or perlite. Ready to use in raised beds and container gardens. Density: 0.80-0.95 t/yd³ (lighter than pure topsoil due to organic content). Cost: $40-80/yd³ bulk, $5-8 per 1 ft³ bag.

Compost

Decomposed organic matter — primarily a soil amendment, not a base soil. Mix at 25-30% with topsoil for vegetable beds. Don't plant directly in pure compost (too rich, holds too much water). Density: 1.10 t/yd³. Cost: $25-50/yd³.

Clay soil

Heavy, fine-particle soil. Holds water and nutrients well but compacts under pressure and drains poorly. Improve with sand and compost rather than removing entirely. Density: 1.60 t/yd³ — heaviest common soil. Free in many regions (your existing yard may be it).

Loam (premium soil)

The ideal soil mix: roughly 40% sand, 40% silt, 20% clay with organic matter. Drains well but holds nutrients. Sold as "premium loam" or "screened loam" at $40-70/yd³. The gold standard for vegetable gardens, lawns, and most plantings.

Soil Needs by Project Type

Different projects use different soil amounts and types. Quick guide to common scenarios:

Raised garden beds

4x4 bed at 12": 0.59 yd³ (16 ft³ / 16 bags)
4x8 bed at 12": 1.19 yd³ (32 ft³ / 32 bags)
4x8 bed at 18": 1.78 yd³ (48 ft³)
3x6 bed at 12": 0.67 yd³ (18 ft³)

Use garden soil mix (premixed with compost) or build your own from 60% topsoil + 30% compost + 10% amendment. For deep-rooted vegetables (tomatoes, root crops) use 18+ inch beds.

New lawn installation

500 sq ft at 4": 6.2 yd³ topsoil
1,000 sq ft at 4": 12.3 yd³
1,000 sq ft at 6": 18.5 yd³
2,500 sq ft at 4": 30.9 yd³

Till new topsoil into the top 6-12 inches of existing soil — don't just layer. Pure topsoil layers create a drainage barrier where roots can't penetrate downward. Mix thoroughly with a rototiller before seeding.

Tree planting

Small tree (1-2" caliper): 1-2 yd³ topsoil amendment in hole 3x rootball width
Medium tree (3-4" caliper): 3-5 yd³ topsoil + compost mix
Large tree (5"+ caliper): 7-15 yd³ (consider professional planting)

Grade leveling / fill projects

Small low spot (6x6 ft at 6"): 0.33 yd³ fill dirt
Driveway prep (200 sq ft at 6"): 3.7 yd³
Major yard regrade (1,000 sq ft at 8"): 24.7 yd³

Soil Weight Reference Table

How much different soil types weigh per cubic yard — important for delivery weight limits and DIY hauling capacity:

Soil type	Density (lb/yd³)	Density (tons/yd³)	Density (kg/m³)
Garden soil mix (light)	1,600 lb	0.80 t	949
Peat / amended mix	1,900 lb	0.95 t	1,128
Compost (finished)	2,200 lb	1.10 t	1,306
Topsoil (dry)	2,600 lb	1.30 t	1,543
Loam (mixed)	2,800 lb	1.40 t	1,662
Fill dirt (dry)	2,900 lb	1.45 t	1,721
Topsoil (wet)	3,000 lb	1.50 t	1,780
Clay soil (dry)	3,200 lb	1.60 t	1,899
Wet clay	3,600+ lb	1.80+ t	2,135+

Pickup trucks have payload limits typically 1,000-2,000 lb. A standard 1/2-ton pickup legally hauls about 1 cubic yard of topsoil. Larger 3/4-ton trucks: 1.5 yards. Hauling more invites suspension damage and traffic stops.

Bulk vs Bagged Soil: When to Switch

For small projects bagged soil is convenient. For anything substantial, bulk delivery dominates on cost:

Project size	Bags needed (1 ft³)	Bulk equivalent	Cost comparison
1 small raised bed (4x4)	16 bags	0.6 yd³	$80 vs $21 ($59 saved)
1 raised bed (4x8)	32 bags	1.2 yd³	$160 vs $42 ($118 saved)
2 raised beds (4x8 ea)	64 bags	2.4 yd³	$320 vs $84 ($236 saved)
Lawn 500 sq ft @ 4"	167 bags	6.2 yd³	$835 vs $217 ($618 saved)
Lawn 1,000 sq ft @ 4"	333 bags	12.3 yd³	$1,665 vs $430 ($1,235 saved)

Even accounting for $50-150 delivery fees, bulk wins decisively above 0.5 cubic yards. The breakeven is even lower for premium garden mixes — bagged "garden soil" at home improvement stores is the most expensive way to buy soil per cubic foot.

Best Soil Mixes for Common Projects

Pre-blended mixes save effort. Make-your-own saves money. Recipes for the most common applications:

Mel's mix (Square Foot Gardening — vegetables)

1/3 compost (mix multiple sources for best results)
1/3 peat moss or coco coir
1/3 vermiculite
Cost: ~$80/yd³ DIY, vs $120+ premixed

Vegetable garden raised bed

60% quality topsoil
30% finished compost
10% peat moss or aged manure
Cost: ~$35-50/yd³ DIY

Container / pot mix

40% peat moss or coco coir
30% compost
20% perlite or vermiculite
10% topsoil (optional, adds weight for stability)

Lawn / sod base

80% screened topsoil
20% compost
Tilled into existing soil at 4-6 inch depth

Common Soil Mistakes

Using fill dirt where you want plants: Fill dirt is for raising grade only. Plants won't thrive without topsoil + organic amendment.
Layering instead of mixing: Pure topsoil over compacted subsoil creates a drainage barrier. Always till new soil into existing 6-12 inches.
Ignoring drainage: Soil without drainage = waterlogged, dead plants. Slope grades 1-2% away from buildings and toward drains.
Over-amending: 100% compost beds drown plants from too much moisture. Stick to 30% compost max in planting beds.
Buying bagged for large projects: The single biggest waste in landscape budgeting. Switch to bulk above 0.5 yd³ — always.
Forgetting settling: A "filled" bed will be 2-3 inches lower in 6 months. Overfill or plan a top-up at 4-6 weeks.

Frequently Asked Questions

How much soil do I need for my garden?

Calculate area in square feet, multiply by depth in inches, then divide by 324 for cubic yards. A 4x8 ft raised bed at 12 inches deep needs 32 cubic feet (1.2 yd³). For a 200 sq ft garden at 6 inches deep: 3.7 cubic yards. Add 10% for settling.

How much does a yard of soil weigh?

Dry topsoil weighs about 2,600 lb (1.3 tons) per cubic yard. Wet topsoil hits 3,000-3,400 lb. Garden soil mixes are lighter at 1,600-1,900 lb/yd³. Heavy clay soil is 3,200 lb/yd³ dry, up to 3,800 lb wet. Account for moisture when checking delivery weight limits.

What's the difference between topsoil, fill dirt, and garden soil?

Topsoil is the dark, organic-rich layer suitable for lawns and gardens. Fill dirt is subsoil without organic matter — used to raise grade or fill holes. Garden soil is topsoil mixed with compost and amendments for direct planting. Use the right type — fill dirt won't grow plants well.

How much soil do I need for a raised bed?

A 4x4 ft raised bed at 12 inches deep needs 16 cubic feet (~0.6 yd³). 4x8 at 12 inches: 32 cubic feet (~1.2 yd³). 3x6 at 12 inches: 18 cubic feet (~0.7 yd³). Use a 60% topsoil + 30% compost + 10% peat moss mix for productive vegetable beds.

How much does a yard of soil cost?

Bulk topsoil costs $20-50 per cubic yard delivered in 2026, depending on quality and region. Screened topsoil with amendments: $35-65/yd³. Premium garden mixes: $50-80/yd³. Delivery typically adds $50-150. Bagged soil (1 ft³ at $4-8) works out to $108-216 per cubic yard equivalent.

How much soil for a new lawn?

Apply 4-6 inches of topsoil for new lawn installation. A 1,000 sq ft area at 4 inches: 12.3 cubic yards. At 6 inches: 18.5 cubic yards. Mix with existing soil (don't just layer) by tilling for the top 8-12 inches — pure topsoil layers create drainage problems.

How many bags of soil in a cubic yard?

Standard bagged soil is 1 cubic foot per bag, so 27 bags equal one cubic yard. At $4-6 per bag, that's $108-162 per yard equivalent — versus $25-50 bulk delivered. For projects over 0.5 cubic yards, bulk delivery is much cheaper.

How deep should soil be for grass?

For new lawns, install 4-6 inches of topsoil over compacted subsoil. Existing lawn overseeding needs only 1/4 inch top dressing. Grass roots typically extend 6-12 inches deep, so 6 inches of quality soil is sufficient for healthy lawn establishment in most climates.

Can I use bagged soil for raised beds?

Yes, for small beds. Bagged garden soil (premixed with compost) works well for 1-2 small raised beds. For larger projects, bulk delivery of topsoil + separate compost is significantly cheaper and lets you customize the blend. The 0.5 cubic yard threshold is where bulk pays off.

What's the best soil mix for vegetable gardens?

The classic vegetable garden mix: 60% quality topsoil, 30% finished compost, 10% peat moss or aged manure. For 1 cubic yard of mix, you need 0.6 yd³ topsoil, 0.3 yd³ compost, and 0.1 yd³ amendment. Mix thoroughly before adding to beds.

How long does soil need to settle?

Freshly delivered topsoil settles 10-20% over the first 6 months as air gaps compress and organic matter decomposes. For raised beds, overfill by 2-3 inches initially. For grade leveling, return after 4-6 weeks to top up any depressions before final seeding.

How much fill dirt for a hole or low spot?

Multiply length × width × depth in feet to get cubic feet, then divide by 27 for cubic yards. A 6x6 ft area that needs 12 inches of fill: 36 cubic feet (1.3 yd³). For larger grading projects, plan on hauling 50-100 cubic yards per truck delivery.