Herringbone Floor Calculator

How the herringbone floor calculator works

Enter the floor area, the width and length of one block, a wastage allowance and the price of one block. The calculator adds the wastage to the floor area to get the area to order, divides that by the area of one block, and rounds up to a whole block. It also shows how many blocks cover one square foot or square metre, how to split the count if your product comes as left and right blocks, and what the block price works out to per unit of area.

The formula is N = ⌈A × (1 + w) ÷ (L × W)⌉, where A is the floor area, w is the wastage as a decimal, and L and W are the block length and width in the same unit as the area. On the US units side the block is entered in inches, so the calculator divides its area by 144 to get square feet. On the metric side it is entered in millimetres and divided by 1,000,000 to get square metres.

Two worked examples

A 12 m² room with 70 × 280 mm blocks, the size of one of Havwoods’ European Oak herringbone blocks: one block covers 0.07 × 0.28 = 0.0196 m², so a square metre takes 1 ÷ 0.0196 = 51.0 blocks. With 15% wastage the area to order is 12 × 1.15 = 13.8 m², and 13.8 ÷ 0.0196 = 704.1, so the room needs 705 blocks. At £1.80 a block that is £1,269, which works out to 1.80 ÷ 0.0196 = £91.84 per m².

A 120 ft² room with 3 × 12 in blocks: one block covers 36 in², or 36 ÷ 144 = 0.25 ft², so a square foot takes 4 blocks. With 15% wastage the area to order is 120 × 1.15 = 138 ft², which is 138 ÷ 0.25 = 552 blocks. At $2.50 a block the total is $1,380, or $10.00 per ft².

Choosing the wastage allowance

Herringbone wastes more than straight boards because every block that meets a wall is cut at an angle. Havwoods, a timber flooring supplier, advises 15% for herringbone and chevron in areas under 100 m² (about 1,076 ft²) and 12% for larger areas, against 10% and 7% for plank floors. The US flooring company Diamond W, in its plank and herringbone installation guide, recommends 5% to 10% for cutting and grading on ordinary installs and an additional 15% for diagonal layouts. The default of 15% follows the Havwoods figure for a typical room; raise it for rooms with many corners, bays or doorways, and for a first attempt.

Buying by the box

Most herringbone is sold in boxes or packs with a stated coverage rather than by the block. Divide the area to order by the coverage of one box and round up. If a box covered 1.2 m², for example, the 13.8 m² room above would need 13.8 ÷ 1.2 = 11.5, so 12 boxes. To compare a price quoted per box or per square metre with the per-block price, use the price per unit of area line in the result.

Left and right blocks

Some herringbone is made in left-handed and right-handed versions, often marked A and B. UK Flooring Direct’s herringbone installation guide describes A/B packs with equal numbers of each hand, and A-only packs where every board is the same and joins using opposite sides. Diamond W's blocks are universal, with one tongue and three grooves. If your product is A/B, the count is split in half and each half rounded up, so an odd total gains one block. Sorting the blocks into two piles before starting saves time on site.

Setting out

All three installation guides cited here start the pattern from a centre line. Diamond W describes finding the centre of the room, marking a centre line, running the apex of the first row along it, and usually running the pattern along the length of the room. The first rows set the angle for the whole floor, so they are the part to get exactly square. Leave an expansion gap at every wall and fixed object as the product instructions specify; Urban Floor’s Timbertop herringbone guide, for example, asks for at least 5/8 in (15 mm) around the perimeter for its engineered blocks.

What this tool does not do

It does not plan a layout, count border blocks separately, or allow for adhesive, underlay or trims. It treats the floor as one area, so for an L-shaped room add up the rectangles first. It does not check the subfloor, which the product's installation guide covers.

Using this calculator with other BuildMetricLab tools

The hardwood floor calculator covers straight-laid boards, the self-leveling compound calculator helps flatten the subfloor first, and the baseboard calculator covers the trim around the room. All BuildMetricLab tools run in your browser with no sign-up, and every formula is shown on the page so the maths can be checked.