| Bed (L × W × H) | Board | Board length | Waste | Boards with waste | Estimated cost |
|---|---|---|---|---|---|
| 8 ft × 4 ft × 18 in | 2x6 cedar | 8 ft | 10% | 18 | $270.00 |
| 2.4 m × 1.2 m × 40 cm | 1x8 cedar | 12 ft | 12% | 14 | $224.00 |
| 6 ft × 2 ft × 12 in | 2x4 cedar | 6 ft | 8% | 12 | $156.00 |
Layers: layers = ceil(height_in / board_width_in) when Auto is selected.
Segments per side: segments = ceil(side_length_ft / board_length_ft).
Boards per layer: 2×segments(length) + 2×segments(width).
Boards with waste: ceil(boards_total × (1 + waste%/100)).
Board feet: (thickness_in × width_in × length_in) / 144 per board, multiplied by purchased board count.
- Measure the outside length and width of your garden bed.
- Enter the planned height or number of stacked layers.
- Select your cedar board size and the board length you can buy.
- Set a waste factor to cover cutoffs and defects.
- Add prices if you want an estimated total cost.
- Press Calculate to show results above the form.
- Use the CSV or PDF buttons to export your plan.
Sizing the raised bed perimeter
Perimeter drives most lumber use because boards wrap the outside edge. The calculator converts meters to feet, then uses perimeter = 2 × (L + W). For a common 8 ft × 4 ft bed, perimeter equals 24 ft. If you build multiple beds, run each layout separately and sum purchased boards for an accurate shopping list.
Layer planning from board face width
Bed height controls how many horizontal layers you stack. In Auto mode, layers are calculated by ceil(height ÷ board_width) using the board’s actual face width. For example, an 18 in height with a 2×6 (5.5 in face) yields 4 layers. Manual mode is best when you plan a capped top, a partial buried layer, or a stepped design.
Board count, splices, and linear feet
Each side is split into segments based on the board length you can buy. Segments are ceil(side_length ÷ board_length), then boards per layer become 2×segments(L) + 2×segments(W). Longer stock reduces joints, improves stiffness, and lowers fastener demand. The report shows theoretical linear feet and purchased linear feet so you can compare efficiency across board lengths.
Waste allowance and board-foot tracking
Waste covers knots, end checks, trimming, and layout changes. A 10% factor is a practical baseline for clean rectangular beds; raise it to 12–15% for miters, corner details, or visible-grade selections. Board feet are calculated as (T × W × L) ÷ 144 using inches, which helps you benchmark material volume when comparing different board sizes.
Cost planning and exportable cut lists
Enter a price per board to estimate lumber cost, then optionally include corner posts and screws. Posts default to four pieces, with length set to bed height plus an adjustable extra allowance. The CSV export captures inputs, results, and a pieces summary for quick quoting. The PDF export produces a clean one-page record that’s easy to share on-site. For budgeting, compare several board lengths and waste rates before buying, then lock one plan.
FAQs
1) Which dimensions should I measure?
Measure the outside length and outside width of the finished bed. Use the planned wall height above ground. If you will bury the first board, subtract that buried height or use Manual layers.
2) Does it use nominal or actual board sizes?
The presets use typical actual thickness and face width for common sizes. That improves board-foot estimates and layer planning. If your stock is milled differently, turn on the custom dimension toggle and enter true measurements.
3) Why do my results show splices?
When a side length is longer than the board length you selected, the calculator splits that side into multiple segments. Choosing longer boards reduces joints and can lower the screw estimate if you enable fasteners.
4) What waste percentage should I choose?
Use 8–10% for straight cuts and simple rectangles. Use 12–15% when boards must be color-matched, when you expect defects, or when you plan decorative corners, caps, or angled cuts.
5) Are corner posts required?
They are optional. Posts improve rigidity on taller beds and help keep corners square during assembly. If you use metal brackets or lap joints instead, leave the posts toggle off to keep totals focused on boards.
6) What do the exports include?
CSV includes inputs, key results, and the pieces summary in a spreadsheet-friendly format. PDF creates a simple, printable record of the same information. Both exports use your most recent calculation.