How to measure for your elevated planter box project
- Enter your box size and leg height. Type in the box length, width, and soil depth in inches. Eight inches of depth suits greens and herbs; bump it to 10-12 inches for tomatoes or root crops. Set leg height to 30 inches for a comfortable standing-height work surface, or 18 inches if you want a lower bench or kids' planter.
- Choose your side board. Select 1x6 cedar (rot-resistant, lightweight, and the most popular choice for edibles), 2x6 lumber (thicker and sturdier but heavier), or fence pickets (the cheapest option -- grab the dog-ear pickets at any home center). The calculator adjusts the cut list automatically for board thickness.
- Read the cut list and buy materials. You get a cut list for every part -- legs, long sides, short sides, bottom slats, and top trim -- plus the total boards to buy, deck screws, soil bags, and landscape fabric. Line the inside with landscape fabric and drill 1/2-inch drainage holes through the bottom slats before filling with potting mix.
How the elevated planter box calculator works
The calculator builds a cut list from your box dimensions and stacks boards row by row based on face width (5.5 inches for 1x6 cedar). Board count = sum of all linear inches per stock group, divided by 96 inches per 8-foot board, multiplied by 1.1 for a 10% waste allowance, rounded up. Soil volume = box length (ft) x box width (ft) x soil depth (ft); bags = ceil(soil cu ft / 1.5). For a 4x2 ft box 8 inches deep: soil = 4 x 2 x (8/12) = 5.33 cu ft, ceil(5.33 / 1.5) = 4 bags. Plants = floor(box area / spacing^2); at 12-inch spacing on 8 sq ft, that is 8 plants. The lumber side uses the same logic: a 4x2 ft box comes to 10 boards across legs, side boards, bottom slats, and trim, matching the reference table.
Which type are you estimating?
1x6 cedar, 8 in deep, 30 in legs (the classic)
The go-to build for edibles. Cedar is naturally rot-resistant, stays light enough to move when empty, and looks good with a single coat of exterior oil. Eight inches of depth is plenty for lettuce, spinach, basil, and most herbs. Thirty-inch legs put the soil surface at counter height so you tend it standing up without bending.
Enter: Side board: 1x6 cedar | Box depth: 8 in | Leg height: 30 in
2x6 lumber, 10-12 in deep, 30 in legs (heavier crops)
Add two more inches of depth for tomatoes, peppers, or carrots -- roots that want room to run. Two-by-six sides are thicker (1.5 in vs 0.75 in) and noticeably sturdier; the finished planter will be heavier, so consider adding casters if you want to move it. The deeper box means more soil bags, so plan on roughly 6-8 bags for a 4x2 ft footprint at 10-12 in deep.
Enter: Side board: 2x6 lumber | Box depth: 10 or 12 in | Leg height: 30 in
Fence pickets, 8 in deep, 30 in legs (budget build)
Dog-ear cedar fence pickets (usually about $2-3 each) are the cheapest way to build a planter. They are the same nominal thickness as 1x6 boards and the calculator treats them identically. They are not as clean-looking, but you can sand the tops smooth and finish them. Good for a first build or a kids' project.
Enter: Side board: Fence picket | Box depth: 8 in | Leg height: 30 in
Low bench height, 18 in legs (kids or seating)
Bring the legs down to 18 inches for a planter that doubles as a seating bench or is sized for children. At that height the soil surface sits at about 26 inches -- comfortable for someone seated on an adjacent bench or for a child working the garden. Everything else in the cut list stays the same.
Enter: Side board: 1x6 cedar | Box depth: 8 in | Leg height: 18 in
Wide box, 6-inch plant spacing (herbs or greens grid)
Drop plant spacing to 6 inches to grow a dense grid of herbs, lettuce heads, or flowers. A 4x4 ft box at 6-inch spacing fits 64 plants. Keep the box to 4 feet wide so you can reach the center from either side without stepping in.
Enter: Box: 48 x 48 in | Box depth: 8 in | Plant spacing: 6 in
Tips & ways to save
- Line the inside of the box with landscape fabric before filling -- it keeps soil in while letting water drain, and it extends the life of the wood by reducing direct soil contact.
- Drill at least four 1/2-inch drainage holes through the bottom slats before you fill with potting mix. Without drainage, roots sit in waterlogged soil and rot.
- The soil box is usually only 8 inches deep, so it needs far less potting mix than a ground bed of the same footprint. A 4x2 ft elevated box takes about 4 of the 1.5 cu ft bags -- not the 10-plus bags you might expect.
- Legs make elevated planters naturally critter-resistant. Rabbits and ground squirrels rarely bother climbing, so you can skip chicken-wire lining in most yards.
- Pre-drill all screw holes near the ends of boards to prevent splitting, especially on cedar. Use exterior-rated deck screws (1-5/8 in for side boards, 2-1/2 in where legs meet the box frame).
Lumber & soil by elevated box size (8 in deep, 30 in legs)
| Box size | Boards to buy | 1.5 cu ft soil bags | Plants (12 in spacing) |
|---|---|---|---|
| 2 × 2 ft | 8 | 2 | 4 |
| 4 × 2 ft | 10 | 4 | 8 |
| 4 × 4 ft | 14 | 8 | 16 |
Boards are nominal 8-ft lengths with 10% waste, split across 2x4 legs, side boards, and 1x2 trim. An elevated box is usually only 8 inches deep, so it needs far less soil than a ground bed of the same footprint.
Frequently asked questions
How much soil does an elevated planter need?
What wood should I use for a raised bed with legs?
How deep should an elevated garden bed be?
Do I need to line an elevated planter box?
What is the ideal leg height for an elevated planter?
How many plants fit in a 4x2 ft elevated planter?
Sources
Related calculators
Reviewed by the BackyardCalc editorial team. Figures are computed from the formula above and checked against manufacturer yields.