Soil Bags Calculator – How Many Bags of Soil for Your Area & Depth

You’re standing in the garden center aisle, staring at a wall of soil bags, and suddenly the math doesn’t feel so simple. How much does one bag actually cover? Do you need 2 cu ft bags or 3 cu ft bags? And how many cubic yards is that, anyway?

Buy too few and you’re making a second trip mid-project. Buy too many and you’re left hauling 20-pound bags back to the car. Neither is fun.

This guide cuts through the confusion. Use the calculator at the top of this page to get your exact number in seconds, then read on for the formula, coverage tables for every common area size, and a straight answer on whether you should be buying bags or bulk soil at all.

Already know your volume in cubic yards, cubic meters or litres? The Bags of Topsoil Calculator turns it straight into small bags, bulk bags and truckloads, while this page starts from your area and depth.

Not sure whether you need topsoil, garden soil, or potting mix? Our guide to what topsoil is and how it compares to other soils breaks it down.

The Simple Formula for How Many Soil Bags You Need

The math is straightforward. You need three numbers: length, width, and depth. Multiply them together to get your total volume, then divide by the size of one bag.

Volume = Length (ft) × Width (ft) × Depth (ft)

Number of bags = Total volume (cu ft) ÷ Bag size (cu ft)

The most common mistake is forgetting to convert depth to feet. Soil depth is almost always measured in inches, but your length and width are in feet. Divide the depth in inches by 12 to convert it.

Quick example: A 10 ft × 10 ft garden bed at 3 inches deep:

• Area = 10 × 10 = 100 sq ft
• Depth = 3 ÷ 12 = 0.25 ft
• Volume = 100 × 0.25 = 25 cu ft
• Bags needed (2 cu ft bags) = 25 ÷ 2 = 12.5 → buy 13 bags
• Add 10% for settling → buy 14 bags

That’s the whole formula. The rest of this guide is just applying it to common scenarios so you don’t have to do the math yourself.

Bags per Cubic Yard: Quick Reference

A cubic yard is 27 cubic feet, so it takes 36 bags of 0.75 cu ft, 27 bags of 1 cu ft, 18 bags of 1.5 cu ft, or 14 bags of 2 cu ft (13.5 rounded up). For litre bags and any other size, the Bags of Topsoil Calculator converts a known volume into bags.

Quick shortcut formula for cubic yards: Cubic Yards = Area (sq ft) × Depth (inches) ÷ 324

That division by 324 works because 1 cubic yard spread 1 inch deep covers exactly 324 square feet.

How Many Bags of Soil for Common Areas

Below are bag counts for common garden bed sizes using 2 cu ft bags (the most widely available size at Home Depot and Lowe’s), with a 10% settling buffer already included.

Note: the 20×40 ft example (800 sq ft at 3 inches) is the point where buying bags stops making economic sense. At that scale, ordering bulk soil by the cubic yard saves you significant money and a lot of lifting.

How Many Bags of Soil for 100 Square Feet?

This is one of the most common questions, so here’s the full breakdown by depth.

At 1 inch deep (light refresh): about 8.3 cu ft → 5 bags of 2 cu ft

At 2 inches deep (standard flower bed): 16.7 cu ft → 9 bags of 2 cu ft (10 with +10%)

At 3 inches deep (new beds, weed control): 25 cu ft → 13 bags of 2 cu ft (14 with +10%)

At 4 inches deep (trees, heavy weed areas): 33.3 cu ft → 17 bags of 2 cu ft (19 with +10%)

If you’re using 3 cu ft bags instead, divide these numbers by 1.5 to get your bag count.

How Many Bags of Soil for 1,000 Square Feet?

At 1000 square feet, the bag count climbs fast depending on depth.

At 1 inch deep: 83 cu ft → 46 bags of 2 cu ft (51 with +10%)

At 2 inches deep: 167 cu ft → 84 bags of 2 cu ft (92 with +10%)

At 3 inches deep: 250 cu ft → 125 bags of 2 cu ft (138 with +10%)

At 4 inches deep: 333 cu ft → 167 bags of 2 cu ft (184 with +10%)

For anything over 2 inches on 1,000 sq ft, buying bags stops making financial sense. Ten cubic yards of bulk soil covers about 1,000 sq ft at 3 inches. At one supplier’s October 2026 prices in our topsoil cost guide that cost 5 unscreened or 5 screened including a trip fee, while 0.75 cu ft bags work out to 0.44–3.64 per yard.

Soil Bags Needed by Area — Full Reference Table

Using 2 cu ft bags, with 10% settling factor added. Depth at 2 inches (standard refresh) and 3 inches (new beds / weed control).

Once you’re past 500–600 sq ft, switching to bulk soil by the cubic yard is usually cheaper and easier.

How Deep Should Soil Be? Depth Guide by Project Type

Depth is the single biggest variable in your bag count calculation — and also the most misunderstood. Too little and weeds push through. Too much and you risk suffocating roots and inviting pests and fungal disease.

The 4-inch maximum rule: never exceed 4 inches of soil depth around plants or trees. More than that creates a mat that blocks water and oxygen from reaching roots and harbors pests. The sweet spot for almost all plantings is 2–3 inches.

Important: if you’re topping up an existing bed, measure what’s already there first. If you still have 1–2 inches of soil in good condition, you only need to top up the difference — not apply a full new layer. This alone can cut your bag count in half.

Soil Bag Sizes Explained

Note on “dm³” sizing: some bags (especially European brands) label volume in dm³ (cubic decimeters) instead of liters — they’re identical units, so a “30 dm³” bag is the same as a 30 L bag. At roughly 25.5 bags per cubic yard, it sits between the 25 L and 50 L sizes above.

Bag sizes are confusing because brands label them differently. Some list cubic feet, some list liters, and some only list weight — which doesn’t tell you the volume.

Soil bags sometimes list weight instead of volume, which can be misleading since moist soil weighs more than dry soil for the same coverage. When the label gives both, use the cubic feet or liter figure — that’s the number this calculator uses — and treat the weight as a rough guide only.

Note on 1.5 cu ft bags: these are common at big-box stores, especially during promotions. They’re less efficient — you need 18 per cubic yard instead of 14 for the 2 cu ft size. If you’re buying in quantity, the 2 cu ft or 3 cu ft bags are better value.

Should You Add a Settling Factor?

Yes, almost always. Fresh soil is loosely packed in the bag. Once spread, it compresses and settles — typically 10–15% within the first few weeks, sometimes more for loose or fluffy soil blends.

Here’s what to add by project type:

• Bagged garden soil or topsoil: add 10% — typical compaction after watering
• Loose or fluffy potting mixes: add 15% — compacts more once settled and watered
• Compost-amended or screened soil: add 10–15% — depends on how finely it’s screened
• Topdressing thin layers: add 5% — very little compaction when spread thin
• Pathways and heavy traffic areas: add 10–15%

The calculator above has a settling factor field built in. Enter your percentage and it adjusts the bag count automatically.

Bags of Soil vs. Bulk Soil — Which Should You Buy?

This comes down to quantity, access, and cost.

As a rule of thumb, bags are fine for small beds and patches, and bulk delivery usually costs less and saves a lot of labor once the volume climbs past a couple of cubic yards.

A cost comparison: for a project needing 3 cubic yards of soil, buying 42 bags of 2 cu ft at each comes to 2. One supplier in our topsoil cost guide listed screened topsoil at per yard with a trip fee, which makes 3 yards of bulk soil 0. Your local prices will differ, so get a delivered quote before you choose.

When to use bags

• You need less than 2 cubic yards total
• You want a specific product (potting mix, raised-bed blend, or a specialty soil amendment) not available in bulk
• Your access is limited — no delivery truck access
• You’re doing a small refresh of just one or two beds
• You don’t mind multiple trips

When to use bulk soil

• You need more than 2 cubic yards
• You’re covering 500+ sq ft of beds
• Cost matters — bulk usually costs far less per cubic foot
• You have driveway access for delivery
• You want to minimize plastic bag waste

Worked Examples

A 10 ft × 2 ft garden bed, one bag covers 10 sq ft — how many bags? Area = 10 × 2 = 20 sq ft. Divide by 10 sq ft per bag = 2 bags exactly.

1,225 lbs of soil, bags weigh 40 lbs each — how many bags? 1,225 ÷ 40 = 30.625, which rounds up to 31 bags — you can’t buy a partial bag, so always round up on weight-based totals like this.

Frequently Asked Questions

How many bags of soil do I need for 200 square feet?

At 2 inches deep: about 33.3 cu ft, which is 19 bags of 2 cu ft (including 10% settling). At 3 inches deep: 50 cu ft, or 28 bags. For the smaller 1.5 cu ft bags, multiply these by 1.33 — so 25 bags at 2 inches, 38 bags at 3 inches.

How many bags of soil or dirt are in a cubic yard?

It depends on the bag size. One cubic yard is 27 cubic feet, so it takes 36 bags of 0.75 cu ft (the common 40 lb bag), 27 of 1 cu ft, 18 of 1.5 cu ft, 14 of 2 cu ft (13.5 exactly, so round up) or 9 of 3 cu ft. The count is the same whether you call it soil or dirt, and the Bags of Topsoil Calculator covers litre sizes.

How many 25 liter (or 30 dm³) bags of soil are in a cubic yard?

A cubic yard holds about 764.5 liters. That works out to roughly 31 bags at 25 L, or roughly 25–26 bags at 30 L (30 dm³ is the same size as 30 L — just a different way of labeling the same volume).

What does 1 bag of soil cover?

The most common bag — 0.75 cu ft (a 40 lb bag) — covers approximately:

• 4.5 sq ft at 2 inches deep
• 3 sq ft at 3 inches deep
• 2.25 sq ft at 4 inches deep

A 1 cu ft bag covers 6 sq ft at 2 inches, 4 sq ft at 3 inches, or 3 sq ft at 4 inches deep. A standard 2 cu ft bag covers approximately:

• 12 sq ft at 2 inches deep
• 8 sq ft at 3 inches deep
• 6 sq ft at 4 inches deep

The 3 cu ft bag covers 50% more: 18 sq ft at 2 inches, 12 sq ft at 3 inches, 9 sq ft at 4 inches.

How much area does a 40 lb bag of garden soil cover?

A 40 lb bag is almost always the common 0.75 cu ft size. At 2 inches deep it covers about 4.5 sq ft, at 3 inches deep about 3 sq ft, and at 4 inches deep about 2.25 sq ft.

How much does a bag of soil weigh?

It depends on the bag size, the product and how wet the soil is, so check the label. The most common size at home improvement stores is a 40 lb bag, which is roughly 0.75 cu ft. Moist or freshly watered soil weighs noticeably more than dry bagged soil.

How many bags of soil do I need for 500 square feet?

At 2 inches deep: about 83 cu ft, or 46 bags of 2 cu ft (with +10% settling). At 3 inches deep: 125 cu ft, or 69 bags. At this quantity, you’re right on the boundary where bulk soil starts making sense. Get a delivery quote before buying bags.

What is the difference between cubic feet and cubic yards for soil?

1 cubic yard = 27 cubic feet. Bags are labeled in cubic feet. Bulk soil is sold and delivered by the cubic yard. To convert bag count to cubic yards: multiply the number of 2 cu ft bags by 2, then divide by 27. For example, 14 bags = 28 cu ft = about 1 cubic yard.

Can soil be too deep?

Yes. More than 4 inches of soil creates a dense mat that blocks water and oxygen from reaching roots, can cause root rot, and creates habitat for rodents and insects. Keep it at 2–3 inches for almost all plantings, and never pile soil against a tree trunk or over the root flare — that traps moisture against the bark and invites rot.

How much soil is in a bag?

Check the volume on the label: US bags are sold in cubic feet (such as 0.75, 1, 1.5, 2 or 3 cu ft) and metric bags in litres (such as 25, 35 or 50 L). A 40 lb bag is roughly 0.75 cu ft, but weight alone does not tell you the volume.

Quick Cheat Sheet

The formula in one line: Volume (cu ft) = Length × Width × Depth (in inches) ÷ 12. Then divide by 2 for standard bags, by 3 for large bags. Add 10%. Round up.

• 1 cubic yard = 27 cu ft = 14 bags (2 cu ft) or 9 bags (3 cu ft)
• 2 inches deep: 1 bag (2 cu ft) covers 12 sq ft
• 3 inches deep: 1 bag (2 cu ft) covers 8 sq ft
• Over 2 cu yds? Bulk soil is usually cheaper
• Settling factor: add 10% for bagged garden soil, 15% for loose potting mixes
• Never go deeper than 4 inches; keep soil away from tree trunks

Use the calculator at the top of this page to skip the math entirely — enter your dimensions, pick your bag size, and you’ll have your number in seconds.

Other Calculators You Might Need

• Raised Bed Soil Calculator: use this if you’re filling a raised bed rather than topdressing an open area — same bag-count logic, different depth.
• Multi-Area Topsoil Calculator: covers multiple beds or sections at once and adds up the total for you.
• Circular Area Topsoil Calculator: built for round beds and tree rings — handles the radius math automatically.
• Topsoil Tons Calculator: use this if your supplier prices material by weight instead of volume.
• Topsoil Cost Calculator: compares bagged vs. bulk pricing so you know which option actually saves money at your quantity.
• Topdressing Topsoil Calculator: use this instead if you’re thinly topdressing an existing lawn or bed rather than filling a new one.
• Lawn Topsoil Calculator: built for filling in low spots or prepping a lawn area before seeding.
• Compost Calculator: use this if you’re layering compost into your soil — same volume formula, different material density.
• Peat Moss Calculator: figures out how many bags of peat moss you need for soil amendment projects.

Daniel

Founder & Editor – TopSoilCalcOnline.com

Daniel is the founder and primary editor of TopSoilCalcOnline.com, a practical resource built to help homeowners, landscapers, and contractors accurately calculate topsoil, compost, and soil mix requirements. With hands-on experience in lawn preparation, raised beds, topdressing, and bulk soil planning, Daniel focuses on turning complex volume calculations into simple, reliable tools. Every calculator and guide on this site is designed to reduce material waste, prevent over-ordering, and help users plan landscaping projects with confidence and precision.