Last Updated on September 18, 2026

Raised Bed Lumber Calculator: Boards to Buy and a Cut List

A raised bed lumber calculator turns your bed’s outside length, width, height and board size into an exact cut list: how many boards to buy, every length to cut, the corner pieces, screws and soil. A 4×8 bed two boards high takes six 8-foot 2x6s, four full-length boards for the long sides and two boards cut into four 45-inch ends, for a bed 11 inches tall (a 2×6 is really 5-1/2 inches wide). Put your own bed in the calculator below for the full list, the corner pieces, braces and the soil to fill it.

The worked example: one 4×8 bed, two 2x6s high

The calculator opens on the bed most people start with: 8 feet by 4 feet outside, two 2x6s high, butt corners. The long sides run the full 96 inches and the ends fit between them, so each end is 48 inches minus two board thicknesses: 48 – 1-1/2 – 1-1/2 = 45 inches.

• Cuts: 4 @ 96 in for the long sides and 4 @ 45 in for the ends.
• Boards: the four 96-inch sides are whole 8-foot boards with no cut. Two 45-inch ends fit on one 8-foot board with room for the saw: 45 + 1/8 + 45 = 90-1/8 inches, leaving about 5-3/4 inches after the second cut. The four ends take two boards, so the bed takes six boards, 48 linear feet.
• Other lengths: 12-foot boards also come to 48 feet (four boards, each cut into a 96 and a 45). 16-foot boards need four, because two 96-inch pieces plus a saw cut come to 192-1/8 inches, 1/8 inch more than the board.
• Brace: one 2×4 across the middle, cut to the 45-inch inside width, plus an 11-inch 2×4 block on each side for it. All three pieces come out of one 8-foot 2×4.
• Soil: the inside is 93 x 45 inches and 11 inches deep, about 26.6 cubic feet or 1 cubic yard.

Penn State Extension’s York County Master Gardeners arrive at the same six boards. Their 4×8 bed, one foot deep, uses six 2×6 by 8-foot boards of untreated pine or fir: two full-length boards on each long side, and each end made from one board sawn in half, two levels high.

Once you know the bed size you are building, you can plan what goes in it. Plan My Garden is free to start: draw the bed at that size and it places each plant at square foot spacing.

Boards to buy for common bed sizes

These are the calculator’s counts for one bed with butt corners and a 1/8-inch saw kerf. Every 2x board is 1-1/2 inches thick, so the counts are the same for 2×6, 2×8, 2×10 and 2×12; only the height changes. The fewest linear feet in each row is in bold. “Too short” means the long side is longer than that board.

Cut lengths are in inches. Braces are extra: on Auto the calculator adds one 2×4 brace for every 4 feet of length past the first 4. For a 4×16 one board high the table says three 16-foot boards; my own 4×16 bed took 2.5 untreated Douglas fir 2x8x16s (it is in my cost breakdown), and the arithmetic agrees: both 45-inch ends plus one saw cut, 90-1/8 inches, fit in half a board.

How tall each board size makes the bed

Lumber is sold by its nominal size, and the board you bring home is smaller. The American Softwood Lumber Standard (NIST PS 20-20) sets the minimum dressed dry sizes: a nominal 2-inch thickness is 1-1/2 inches, and nominal widths of 6, 8, 10 and 12 inches are 5-1/2, 7-1/4, 9-1/4 and 11-1/4 inches. A 4×4 is 3-1/2 by 3-1/2. Penn State Extension’s raised bed build video makes the same point with a 2×4, which is really 1.5 by 3.5 inches, and says to plan your cuts around it.

The calculator rounds up to whole boards, so asking for 12 inches of 2×6 gives three boards and 16-1/2 inches. If you want a foot, a single 2×12 gets you 11-1/4 inches with half the cuts. Green or rough-sawn lumber runs bigger: PS 20 lists a green 2×6 at 1-9/16 by 5-5/8 inches, with separate green size rules for redwood and some cedars. Measure your boards and type the real width and thickness into the calculator.

Corner styles and what each one changes

• Butt corners. The length sides run the full outside length and the width sides fit between them, 3 inches shorter than the outside width. Nothing else to buy. The screws go into the end grain of the short boards, and Penn State’s build video says to screw into posts rather than end grain so the wood does not split. My friend Jeff fastened his corners with lag screws instead, pre-drilling the boards, which leaves the corner open for plants and drip line.
• 4×4 blocks inside the corners. Same side boards, plus four 4×4 blocks as tall as the bed. This is how I built the bed in my raised bed with drip irrigation build, with four screws on each block. It is one of the three things I would change: the blocks eat the corner space, so the drip line cannot reach it and nothing gets planted there.
• 2×4 or 2×2 cleats inside the corners. Same side boards and a smaller block. The York County plan uses a 2×2 by 1-foot piece in each inside corner and 48 3-inch wood or deck screws, 12 per corner. Utah State University Extension screws the corners together with 4-inch decking screws and reinforces them with a wooden block or metal plate inside the corner.
• 4×4 posts at the outside corners. The posts are the corners and every board fits between two posts, so each side is 7 inches shorter than the outside size (two 3-1/2 inch posts).

The screw count in the calculator uses the York County rate, 12 per corner for two courses, which works out to 3 screws per board end. Braces need a few more. If you want the corner pieces to hold the bed in place, tick the stake box: University of Missouri Extension says stakes holding raised bed walls should be twice the height of the bed, with half buried in firm ground, and that stakes on the inside of the boards are hidden once the bed is filled.

Braces keep long sides from bowing

UNH Extension recommends a brace in the middle of any bed over four feet long, so the boards do not bow out under the weight of the soil. The York County Master Gardeners add that deeper beds should be ready for reinforcing on the long sides, which may bow outward as wet soil expands. On Auto, the calculator adds one 2×4 brace for every 4 feet past the first 4: none for a 4×4, one for a 4×8, three for a 4×16. Each brace is a 2×4 cut to the inside width, with a 2×4 block on each side the height of the bed, so the screws go into a block and not into end grain. My own 4×16 bed used a 2×4 cut in half as its brace.

University of Minnesota Extension adds two board tips: shorter boards, 6 feet or less, are less likely to warp or break than longer ones, and turning boards heartwood in means that if they warp, they curve slightly outward at the middle.

Which lumber to use

I have cedar, untreated Douglas fir and metal beds in the same backyard, and the full story is in Cedar vs Pine vs Metal Raised Beds. The short version from a wet New Hampshire climate:

• Untreated Douglas fir 2x8s and 2x12s are the cheapest to build with and to replace. Mine last 7 to 9 years; the 9-year-old beds are hollow with rot in places, and anywhere that stays wet rots first.
• A cedar kit is still solid above ground at 10 years, but the bottom boards have sunk and are rotting, and it costs more.
• Pressure-treated lumber: I do not use it. Untreated fir is cheap enough to replace every eight years or so. UNH Extension notes that USDA organic certification does not allow chemically treated lumber in contact with growing soil.

UNH Extension expects untreated wood beds to last three to five years and cedar or redwood beds 10 years or more, so a drier or wetter yard than mine will move those numbers. If you would rather not rebuild at all, my metal bed is in the Garden In Minutes review.

Lumber prices change too much to print here, so the calculator only shows a cost when you type in your own prices. My 2022 numbers for a 4×16 bed are in the Quick questions below.

Before you cut

• Measure the boards. PS 20 has 2-inch lumber trimmed to no less than its nominal length and no more than 3 inches over. The calculator treats an 8-foot board as exactly 96 inches, so a board that runs long only helps.
• Set the kerf. Each cut turns a strip of wood into sawdust. Wood Gears Lab puts a full-kerf blade at roughly 1/8 inch (0.125) and a thin-kerf blade at roughly 3/32 inch (0.094). The calculator uses 1/8; change it to match your blade.
• Level the ground. Dig out the perimeter of the bed, level the ground, and use the removed soil to fill the bed.
• Stop voles before you fill. Fasten mesh wire to the bottom of the bed before it goes in place, even if you do not think you have voles.
• Overfill with soil. It settles over time. The calculator’s soil number is the inside of the frame; the raised bed soil calculator turns bed sizes into cubic yards and a Mel’s Mix recipe.

Quick questions

How many 2×6 boards do I need for a 4×8 raised bed?

Six 8-foot 2x6s for a bed two boards high, which is 11 inches tall. Four boards are the long sides and two are cut into four 45-inch ends. One board high takes three 8-foot 2x6s, or two 12-foot 2x6s.

How much lumber do I need for a 4×4 raised bed?

With butt corners each course is two 48-inch and two 45-inch pieces. Each 8-foot board gives one of each, so one board high takes two 8-foot boards and two boards high takes four. Two 16-foot boards also cover a bed two boards high.

What size is a 2×6 really?

1-1/2 by 5-1/2 inches when dry, under the American Softwood Lumber Standard. A 2×8 is 7-1/4 inches wide, a 2×10 is 9-1/4 and a 2×12 is 11-1/4, so two 2x6s stack to 11 inches, not 12.

Does a raised bed need a brace in the middle?

UNH Extension recommends a brace in the middle of any bed over four feet long, so the boards do not bow out under the weight of the soil. The calculator adds one 2×4 brace for every 4 feet of length past the first 4.

How much does it cost to build a raised bed?

It depends on your lumber prices, so type them into the calculator. For scale, my 4×16 bed cost $148 to build, fill and plant in 2022: $70 for 2.5 untreated Douglas fir 2x8x16s, $2 for a 2×4 brace, $4 for screws, $60 for about a yard of compost and $12 for seed.

Plan what goes in the bed before you build it

Plan My Garden is free to start: enter your zip code and it finds your frost dates, draw your beds at the size you are about to build, pick your crops, and it places each plant at square-foot spacing and builds a planting schedule from your frost dates.

Related: Raised Bed Soil Calculator · Cedar vs Pine vs Metal Raised Beds · How Many Gallons Is 1 Inch of Water? · How to Build a Raised Garden Bed with Drip Irrigation · 4×8 Raised Bed Garden Layout · Charts and Tools