Raised Bed Lumber Calculator
Work out the boards, courses and corner posts for a raised garden bed from its length, width and height.
How it works
Courses = ⌈height ÷ board width⌉ · Lineal feet = 2 × (length + width) × courses × beds · Boards = ⌈lineal feet ÷ board length⌉
A raised bed is a stacked box: each course wraps the full perimeter, and you stack as many courses as it takes to reach the target height. Multiply the perimeter by the number of courses to get the lineal footage, then divide by the length of board you can buy to get a board count. Add four corner posts to lock the courses together; rot-resistant cedar or a naturally durable species is best for soil contact.
Worked example
An 8 × 4 ft bed 12″ tall built from 6″ boards needs ⌈12 ÷ 6⌉ = 2 courses. The perimeter is 2 × (8 + 4) = 24 ft, so 24 × 2 = 48 lineal feet — six 8 ft boards, plus four corner posts.
Frequently asked questions
What wood is best for a raised bed?
Cedar and redwood resist rot naturally and are the usual choice for vegetable beds. Avoid old pressure-treated lumber near food crops; modern ACQ-treated wood is considered safe by many gardeners but some still line the inside as a precaution.
How tall should a raised bed be?
Six to twelve inches suits most vegetables with good soil beneath. Go 18–24 inches for root crops, poor native soil, or easier access without bending — taller beds simply need more courses of lumber.
Does this calculate the soil too?
No — this counts only the frame lumber. To fill the box, multiply length × width × height for the soil volume, or use a dedicated raised-bed soil calculator.
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This calculator is for educational purposes. Double-check important results before acting on them.