Planning guide
Single or double herringbone: what actually changes
Both patterns lay with any rectangle. What the measured module changes is whether band joints run through or stagger, and what you cut and buy.
Published
Almost every article on this decision tells you to pick whichever you like the look of. A few tell you that your plank must be a whole-number ratio first. The second claim is the one worth clearing up, because it is not true, and it stops people buying a product that would have laid perfectly.
Any rectangle lays as herringbone, single or double, at any ratio. The pattern is generated by two repeat vectors read straight off the piece itself, so there is nothing to divide and nothing left over. We measured that rather than assuming it: on a solved field, 3,600 sample points, every one covered by exactly one piece, at a 3.7:1 ratio and at the 2.5-bundle double that the divisibility rule calls impossible.
What the ratio really decides is how the finished floor looks — whether the butt joints of one diagonal band land on the piece boundaries of the next and run straight across the room, or stagger. That is worth knowing before you buy. It is not a reason to reject a product.
Our herringbone layout planner states it for both patterns, then solves the working-spine position, every perimeter piece and the order quantity. This guide explains the measurement behind it so you can audit the answer with a tape and a calculator.
Measure the installed face and the joint
Herringbone uses identical rectangles meeting at 90 degrees. Chevron is a different pattern: its ends are cut at an angle before the pieces meet.
Everything below depends on the piece you can measure, not the size on the box. For butt-jointed timber or resilient flooring, the installed module can be the covering face itself. Do not include a tongue that disappears into the next piece. For tile, add the intended joint once to each face dimension:
Long module = measured face length + joint
Short module = measured face width + joint
The joint belongs in both directions. Adding it only to the width, or dividing the two face dimensions first and adding a percentage later, changes the geometry.
This also explains why a nominal size can mislead. A tile sold as 3 × 6 inches may be manufactured smaller so its face plus the specified joint occupies an exact 3 × 6 module. Another product may measure a literal 3 × 6 inches and be intended for a different joint. Measure a sample and read its installation instructions. The box name is not a set-out dimension.
The worked 5:1 example
The plan above uses a face measuring 597 × 117 mm and a 3 mm joint. Adding one joint produces installed modules of 600 × 120 mm:
597 + 3 = 600 mm
117 + 3 = 120 mm
For single herringbone, one band is one piece wide. Divide the long module by one short module:
600 ÷ 120 = 5
A whole number. Five short modules meet one long module, so each band’s butt ends land exactly on the piece boundaries of the band beside it and the joints run in continuous lines across the whole floor. This is the crisp, ordered herringbone most reference photographs show.
Now the same product as double herringbone. Each band holds two parallel pieces, so its bundle is two short modules wide:
600 ÷ (2 × 120) = 2.5
Two and a half. The floor still lays — every piece meets its neighbours with no gap and no overlap, and the planner draws all of it — but the joints no longer line up between bands. They step by half a bundle each time, which reads as a looser, woven texture instead of continuous lines.
That is a real choice, and it is the choice this article is about. If you want the lines to run through in double, the nearest face that would do it beside the same 3 mm joint is 477 mm: two bundles of 240 mm make a 480 mm module. Three bundles would need a 717 mm face. Neither is a correction you owe anyone. They are simply the sizes at which double herringbone lines up.
Which ratios line up in double?
An even single ratio also lines up as double, because it halves cleanly. A 6:1 module becomes three two-piece bundles:
6 ÷ 2 = 3
An 8:1 module becomes four. An odd ratio such as 3:1, 5:1 or 7:1 does not halve, so a product whose joints run through in single will stagger in double. Nothing is wrong with the product; you are looking at two different floors made from it.
Two cautions. A measurement close to a whole number is not necessarily meant to be modular — measure several pieces if the product has manufacturing variation. And a click product can have a manufacturer-designed A/B system whose reference geometry is defined differently from the visible face. If the planner’s result conflicts with a product-specific herringbone diagram, follow the manufacturer and ask which dimension establishes its working lines.
Single versus double changes more than scale
Single herringbone creates a finer weave. Double groups two parallel pieces before turning 90 degrees, so each visual stroke is wider. In the same room, that changes where the band boundaries reach the walls. The smallest perimeter piece, number of cuts and fresh-stock count can all change even though both patterns cover exactly the same usable area.
That is why the planner solves the unchosen pattern too. A useful comparison has numbers on both sides: band ratio and joint alignment, smallest perimeter piece, stock pieces and boxes. “Double looks calmer” is an aesthetic observation. It is not enough information to order material or accept a narrow corner triangle.
The A/B balance can matter as well. Some rigid-core herringbone products are supplied as handed planks with different locking profiles. The drawing’s A and B labels identify perpendicular orientations; they do not promise that a box contains those handed pieces in the same ratio. Check the carton and supplier before treating the orientation count as a purchase split.
The centre line is only the first candidate
Whatever the ratio does to the appearance, the floor still has a set-out problem. Manufacturer instructions commonly begin by finding the room centre and establishing working lines for the first A/B pair. That creates a straight, reproducible spine. It does not guarantee good cuts at all four walls.
A diagonal band can meet one wall with a broad trapezoid and the opposite wall with a thin triangle. Moving the spine changes both families together. The planner compares the centred start with offsets across one full repeat and maximises the smallest retained perimeter span. Its result keeps the centred number visible so you can see whether the shift bought anything worthwhile.
Transfer both set-out dimensions: the spine’s distance from the left wall and the phase crosshair’s distance from the top. Dry-lay several A/B pairs and check them against the working line. Karndean’s herringbone instructions explicitly tell installers to monitor drift and keep the installed pieces on their lines. A calculated start does not remove that physical check.
A border is a separate design
A soldier or feature border can remove the outer field’s perimeter triangles. It can also frame the room and conceal how an out-of-square wall meets the weave. But it is not a free fix. The border reduces the inner field, needs its own stock and joints, and creates corner details and a laying sequence.
Do not tick “border” on a calculator that merely draws a rectangle over the same field. To explore the inner weave, you can temporarily reduce the room dimensions by twice a proposed border width. That is only a field comparison, not a border cutting plan. Confirm the actual frame, corners and product rules before ordering.
Carry the module check to the floor
Measure more than one sample if the product has manufacturing variation. Check the room at several points, establish whether the walls are square, and use the expansion or perimeter gap specified for the product.
At the boundary, identify each cut by its piece ID and A/B direction. Mark it on the original stock face from the datum corner shown, cut on the waste side, and dry-fit it before copying the same marks to a group. Mirrored pieces can share a bounding box and still be opposite cuts; the stock-frame outline is the part that matters.
The practical sequence is short: measure the face, include the joint, see what the band ratio does to each pattern’s appearance, compare the solved perimeter cuts and quantities, then order. Both patterns will lay. The choice still belongs before the first box is opened, because it changes what you cut and what you buy.