Figuring out how much soil you need does not have to be guesswork. Whether you are filling a Timberlane Gardens raised bed for the first time or topping off an established bed in spring, this guide walks you through the numbers in plain language. You will find the calculator embedded below, along with real examples and soil mix tips that come from years of hands-on gardening.
This page covers:
If you are still deciding which raised bed size and depth to use before you plug in the numbers, our Complete Cedar Raised Garden Bed Comparison Guide walks through the most common Select Cedar raised bed sizes, depths, and layouts we build so you can compare options before you start buying soil.
If you are researching the “best” setup for vegetables or shopping for something easier to manage in a smaller yard, these two buyer guides help narrow it down fast: Best raised garden beds for vegetables and Raised garden beds for seniors, beginners, and small yards.
If you are shopping for a new bed, you can always browse our full collection of Select Cedar raised garden beds. You can also explore all gardening products in one place on our All gardening products page.
Measure the inside length, inside width, and the soil depth you plan to fill. Convert inches to feet, then calculate length × width × depth to get total cubic feet. For Timberlane Gardens beds, use 5 inches for shallow-root crops, 10 inches as a strong all-purpose depth for many vegetables, and 15 inches when you want extra root room for deeper-rooted crops. If you would rather skip the math, use the calculator below and it will estimate cubic feet, cubic yards, and common bag counts.
You only need three measurements:
The easiest way is to measure inside the bed from board-to-board, since soil sits within the interior dimensions. Timberlane Gardens beds list both exterior and interior dimensions, and the soil calculator automatically uses the correct interior measurement when you are on a specific product page.
The basic formula is simple:
Length × Width × Depth (in feet) = Total cubic feet of soil
If your measurements are in inches, divide each number by 12 first. Most gardeners find it faster to use the calculator below, but it is still helpful to understand the math behind the tool.
Your depth depends on what you plan to grow. These guidelines match how Timberlane Gardens beds are actually used, including our modular 5-inch courses:
Timberlane Gardens raised beds are offered in 10-inch and 15-inch depths, and they are modular by design. That means a 10-inch bed can be used as two separate 5-inch beds, and a 15-inch bed can be used as three separate 5-inch beds when you want shallow depth for quick crops like salad greens and radishes. The soil calculator works for every configuration.
Here are a few real examples so you can see the math behind the calculator.
3×3 raised bed at 10 inches deep
3 ft × 3 ft × 0.83 ft = 7.5 cubic feet of soil
4×4 raised bed at 10 inches deep
4 ft × 4 ft × 0.83 ft = 13.3 cubic feet of soil
3×6 raised bed at 10 inches deep
3 ft × 6 ft × 0.83 ft = 15.0 cubic feet of soil
3×6 raised bed at 15 inches deep
3 ft × 6 ft × 1.25 ft = 22.5 cubic feet of soil
These examples are built into the calculator, so you do not have to run the numbers yourself.
This is the same calculator included on all Timberlane Gardens raised bed product pages. When you use it there, it auto-populates your exact bed dimensions. Here on this page, you can enter any raised bed size you want.
Preset Timberlane Gardens sizes use the interior growing dimensions of our beds. If you enter your own measurements, the calculator will use the exact numbers you provide, which may differ from the preset Timberlane Gardens dimensions because of our mortise-and-tenon corner design.
When you choose a size, the calculator will auto-fill the dimensions so you can compare soil volume between beds.
Tip: Most bagged soil is sold in 1.0, 1.5, or 2.0 cubic foot bags. It is usually better to round up a bag or two than to run short in the middle of filling a bed.
These numbers are estimates. It is usually smart to round up slightly to account for settling and imperfect bed filling.
Once you know your total volume, the next step is choosing a mix. A dependable raised bed mix usually includes:
If you are filling a deep bed, it is common to use the “layered” method with coarse wood or branches in the bottom quarter, then your main mix above it. This saves money without affecting plant performance.
For step-by-step soil recipes, ingredient breakdowns, and amendment ideas, visit the Ultimate Raised Bed Soil Guide.
Bagged soil varies by brand, but most standard garden soil bags contain either:
Once the calculator shows your total, divide by the bag size you plan to use. It is better to round up slightly since raised beds settle over time.
Yes. The tool accepts any measurements, so you can use it for custom beds, older beds, or anything you have built yourself.
It is accurate down to the decimal. Variations only come from how tightly you pack soil or how much the bed settles over time.
Yes. Most beds settle by 10 to 20 percent in the first few weeks. This is normal and why gardeners usually top off beds once or twice each season.
Ten inches is the most versatile depth for general vegetable gardening. If you love tomatoes or root crops, consider stepping up to fifteen inches.
You can view our full line of tool-free Select Cedar raised beds here: Cedar raised garden beds. All products are handcrafted locally and ship nationwide.
All Timberlane Gardens raised beds include real warranty coverage: 90-day limited warranty on B-Stock, 1-year standard warranty, and up to 3 years on premium products.
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Cedar raised garden bed kits and planters made in the USA. Handcrafted from Select Cedar in Homer Glen, Illinois — sustainably built for lasting beauty, simple tool-free assembly, and organic growing.
