Landscape Timber Calculator

How the landscape timber calculator works

Landscape timbers, railroad ties and garden sleepers all get used the same way: laid end to end round a raised bed, a border or a low step, sometimes stacked two or three high. This calculator counts how many you need. It multiplies the run by the number of courses, divides by the length of one timber, adds 5% for cuts at the corners and ends, and rounds up to a whole timber.

With the US defaults, a 33 ft run of 8 ft timbers is 33 ÷ 8 = 4.13 timbers, 4.33 with the 5% allowance, so 5 timbers, $175 at $35 each. The metric default, a 10 m run of 2.4 m sleepers, is 4.17 sleepers, 4.38 with the allowance, so 5 sleepers, £140 at £28.

Measuring the run

For edging, the run is simply the length of the border. For a raised bed it's the perimeter: add the four sides. For a curved border, lay a garden hose along the line, mark the ends and measure the hose; straight timbers will need extra cuts to follow the curve, so the 5% allowance may not be enough. Measure along the line the timbers will actually sit on. If the corners overlap, measuring the outside of the bed on one pair of sides and the inside on the other avoids counting each corner twice.

For a stacked bed, the courses multiply the whole perimeter. An 8 ft by 4 ft bed three timbers high has a perimeter of 24 ft and a total run of 72 ft, which is 9 timbers of 8 ft before the allowance and 9.45, so 10, with it. The metric equivalent, a 2.4 m by 1.2 m bed two sleepers high, is 14.4 m of run: 6 sleepers exactly, 7 with the allowance.

Check the count side by side

On a small bed it's worth counting each side, because offcuts only help if they fit somewhere else. In the 8 by 4 ft bed, each course takes two full 8 ft timbers for the long sides and one timber cut in half for the two ends: 3 per course, 9 in all, with no waste at all. The 5% allowance adds a tenth timber, which you may not need on a layout that neat. A 10 by 5 ft bed of 8 ft timbers is the opposite case: the 10 ft sides each need a full timber plus a 2 ft piece, and the two 2 ft pieces and two 5 ft ends come out of two more timbers, so the side-by-side count and the calculator both give 4.

Choosing timber, and what to avoid

Treatment matters as much as quantity, especially for vegetable beds. Many railroad ties and reclaimed railway sleepers are treated with creosote. The US Environmental Protection Agency's creosote page notes that creosote products aren't sold to homeowners, that treated railroad ties are sometimes reused as landscaping timbers, and that such reuse isn't regulated under federal pesticide law. It also warns never to burn creosote-treated wood at home, and says disposal usually goes with household waste, subject to state or local rules.

The UK is stricter. The Health and Safety Executive's 2025 opinion on creosote summarises the UK REACH restriction: wood already treated with creosote for industrial uses can't be used in parks, gardens, playgrounds or other places with a higher risk of skin contact, nor inside buildings or for garden furniture or toys. For a UK garden, that rules out old creosoted railway sleepers and points to new timber sold for garden use. Other countries have their own rules on treated wood, so check what applies where you live.

Building with the count

The calculator treats every timber as the same length and every course as running the full perimeter. Stagger the joints so they don't line up from one course to the next, and fix the courses to each other and to the ground so a stacked bed doesn't spread when it's filled with wet soil. Taller beds and anything retaining a slope put real pressure on the timbers and need more than a stack of sleepers; get advice before building one of those, or anything next to a path or boundary.

Filling the bed

Once the frame is counted, the soil is the next order, and it's a straight volume sum: inside length × inside width × fill depth. Use the inside measurements, since the timbers take up some of the footprint. A bed measuring 8 ft by 4 ft inside and filled 1 ft deep holds 32 ft³, about 1.19 cubic yards; one measuring 2.4 m by 1.2 m inside, filled 0.4 m deep, holds 1.15 m³. Allow a little more for settling if you fill with loose soil.

The price per timber is only a placeholder. Landscape timbers, new garden sleepers and reclaimed railroad ties sell at very different prices, so enter the figure for the product you've chosen.