How deep should the soil be in a raised bed?

For most vegetables and flowers, fill 10 to 12 inches deep. Deep-rooted crops like tomatoes, carrots, and potatoes are happiest at 18 inches. If your bed sits on open ground rather than a hard surface, roots can push a little deeper, so you can fill toward the lower end.

How many bags of soil are in a cubic yard?

A cubic yard is 27 cubic feet. Our bags hold 1.5 cubic feet each, so one yard equals about 18 bags. Once you're past roughly 12 to 15 bags, bulk soil by the yard is usually cheaper and a lot less lifting.

Can I reuse last year's raised-bed soil?

Yes — old bed soil isn't dead, it's just hungry. Most beds drop an inch or two each season as organic matter breaks down. Top off with fresh blend and a scoop of compost or worm castings to refill the volume and feed the soil biology back up.

Is bagged or bulk soil better for filling a raised bed?

It's the same soil — the choice is about volume and price. Bags are easy for one small bed or a balcony. For a full bed or several, bulk by the cubic yard costs less per foot and we can deliver it across Butte County. Our calculator shows both so you can compare.

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Raised BedsSoil VolumeGetting Started

How Much Soil Do I Need for a Raised Bed?

The simple formula for raised-bed soil — measure, multiply, and convert to bags or cubic yards — with a worked example and how deep to fill for healthy roots.

The Earthworm Soil Factory TeamJune 16, 2026

Measure your bed in feet, multiply length × width × depth for cubic feet, then divide by 27 for cubic yards or by 1.5 for the number of bags. A standard 4×8 bed filled a foot deep needs about 1.2 cubic yards — roughly 22 of our 1.5-cubic-foot bags.

Filling a raised bed is the one garden math problem that stops people at the checkout: order too little and you're back for more mid-project, order too much and you're stockpiling soil you didn't need. Here's the simple way to get it right the first time.

The 30-second formula

Every soil-volume question comes down to one line:

Length × Width × Depth (all in feet) = cubic feet.

If your measurements are in inches, divide by 12 first. Eighteen inches deep is 1.5 feet. Then:

Cubic feet ÷ 27 = cubic yards (how bulk soil is sold and delivered)
Cubic feet ÷ 1.5 = number of bags (our bags hold 1.5 cubic feet each)

A worked example

Say you've built a classic 4-foot by 8-foot bed and you want a full 12 inches of soil:

4 × 8 × 1 = 32 cubic feet
32 ÷ 27 = 1.2 cubic yards
32 ÷ 1.5 = about 22 bags

Go 18 inches deep for tomatoes or carrots and that same bed jumps to 48 cubic feet — about 1.8 yards. Depth is the number people underestimate most, so measure it honestly.

How to calculate soil for a raised bed

Total time: 5 min

Supplies

Tape measure
Calculator (or our soil calculator)

1
Measure in feet
Measure the bed's length, width, and how deep you want to fill it — all in feet. For inches, divide by 12 (so 18 inches = 1.5 feet).
2
Multiply for cubic feet
Length × width × depth = cubic feet. A 4 ft × 8 ft bed filled 12 inches deep is 4 × 8 × 1 = 32 cubic feet.
3
Convert to yards or bags
Divide cubic feet by 27 for cubic yards, or by 1.5 for the number of 1.5-cubic-foot bags. 32 cubic feet is about 1.2 yards, or 22 bags.
4
Add a little for settling
Fresh soil settles as it's watered in. Order about 10% extra so you can top the bed back up without a second trip.

Bags or bulk?

It's the exact same soil either way — the only question is how much lifting and how much money. Since a cubic yard is about 18 bags, the math tips toward bulk fast. As a rule of thumb, once a project needs more than a dozen bags, ordering by the cubic yard usually costs less per foot, and we'll bring it to you instead of you stacking sacks in the car.

Which blend goes in a raised bed?

That depends on what you're growing and how much you need. Our soil calculator makes a blend suggestion based on your volume, and each product page spells out exactly what the mix is built for. For most single raised beds, gardeners reach for our Premium Blend; when you're filling several beds or a big planter run, the Garden Blend stretches the budget further. Either way you're getting soil that's hand-mixed here on Clark Road — not bagged bark with a green label.

When you've got your number, run it through the calculator to see bags and bulk side by side, then we'll get it loaded or out on a truck.

Frequently asked questions

How deep should the soil be in a raised bed?: For most vegetables and flowers, fill 10 to 12 inches deep. Deep-rooted crops like tomatoes, carrots, and potatoes are happiest at 18 inches. If your bed sits on open ground rather than a hard surface, roots can push a little deeper, so you can fill toward the lower end.
How many bags of soil are in a cubic yard?: A cubic yard is 27 cubic feet. Our bags hold 1.5 cubic feet each, so one yard equals about 18 bags. Once you're past roughly 12 to 15 bags, bulk soil by the yard is usually cheaper and a lot less lifting.
Can I reuse last year's raised-bed soil?: Yes — old bed soil isn't dead, it's just hungry. Most beds drop an inch or two each season as organic matter breaks down. Top off with fresh blend and a scoop of compost or worm castings to refill the volume and feed the soil biology back up.
Is bagged or bulk soil better for filling a raised bed?: It's the same soil — the choice is about volume and price. Bags are easy for one small bed or a balcony. For a full bed or several, bulk by the cubic yard costs less per foot and we can deliver it across Butte County. Our calculator shows both so you can compare.