A fit-out contractor in Qatar won the atrium package for a shopping mall and ordered a curved LED video wall for a wall measured at 18.9 metres across, radius 12 metres. That is what the RFQ said. The supplier read 18.9 metres as the straight distance between the two ends and cut the steel frame to match. It arrived 1.9 metres too long, 94 centimetres of overhang at each end, and no way to fit it between the marble returns. The frame was remade for USD 38,000 and six weeks, on a USD 210,000 screen package.
Nobody was careless. Two people used the same word, width, for two different measurements.
Why Curved Is Not A Specification
A curved LED video wall cannot be quoted from the word curved. The same adjective covers a 90-degree atrium sweep, a 3-metre lobby arc and a panel wrapped around a 600-millimetre column, and those are three different products with three different frames.
The curved LED video wall in Qatar was a 90-degree sweep. Arc length 18.85 m, chord 16.97 m, sagitta 3.51 m, radius 12 m, included angle 90 degrees. Five numbers, one wall, and any three of them fix the other two. Leave them unlabelled and the supplier has to guess, and the guess stays invisible until steel shows up.
The Five Numbers, And Which Three You Actually Need
Radius on its own is the most common figure on an RFQ and the least useful, because nobody can cut steel from a radius with no span attached.
Four combinations work in practice: radius plus included angle, radius plus chord, chord plus sagitta, and arc length plus radius. The third is the pair you get by measuring a real wall on site.
Two of the five are not interchangeable, which is the whole problem. Arc length is always longer than chord. On the Qatar wall the difference was 1.88 metres, and at P2.5 that is nearly 750 pixels. On a curved LED video wall those pixels are either bought or they are not.
Label everything. Write chord 16.97 m rather than width 16.97 m, and say whether the radius is measured to the front face of the LEDs, the cabinet back or the structural wall, because those measure differently. The radii and segment angles we build to are listed on our curved led video wall page, which is the fastest way to find out whether your arc sits inside standard tooling.
Where The Arc Length Trick Costs Real Money
Curved screens are measured and priced on the developed arc, not on the straight line between the ends. That is honest, because the panels really do cover 18.85 metres of material, but it surprises buyers who costed the wall off the plan. On the Qatar wall the gap was 11% of the surface area, and the LED surface is the expensive part. Ask for both figures, developed and projected, and be suspicious of a supplier who only quotes one. The gap widens as the radius tightens, which is why a curved LED video wall quote often lands above a budget built from the plan.
Our curved LED screen range covers flexible modules and segmented cabinets, which are measured the same way but manufactured to different tolerances. Your quote for a curved LED video wall should say which one is being sold.
How To Check The Frame Before The Panels Arrive
Steel is usually procured separately from the screen, which is why a curved LED video wall failure lands between two suppliers with nobody owning it.
Check three things before the panels ship. String a line between the ends and measure the offset at the centre: that is the sagitta, and it had to read 3.51 m on the Qatar wall. Measure along the straight line between the ends, 16.97 m and not 18.85 m. Then check the segment angle at every joint, because a frame that is right at both ends can still be wrong in the middle.
Ask for two tolerances in writing: surface flatness within 2 mm, and joint angle consistent to within half a degree. If the frame misses those, panels will not close up, and a screen supplier will not extend its flatness guarantee to a frame it did not build.
What To Write In The RFQ So It Cannot Be Misread
Eight lines prevent almost every geometry dispute on a curved LED video wall. State the shape, concave, convex or wrap. Give three of the five numbers, each labelled. Name the surface the radius is measured to. Give the wall height, the mounting method, the pixel pitch and the viewing distance. Say who supplies the steel frame and who fits it, and state the maximum joint gap you will accept. Then add one sentence saying which figure is the arc and which is the chord, even though the labels look obvious.
That last line reads like it is insulting the reader. It is not. It is the line that would have saved USD 38,000 in Qatar.
Our curved video wall displays are quoted against exactly these fields, so an inquiry that arrives in this shape comes back comparable with another supplier's.
Quick Answers On Curved Wall Geometry
What if I only know the chord and the sagitta?
That is enough. The radius follows from those two and everything else follows from the radius, which is why most field measurements of a curved led video wall arrive in that shape.
Is the radius measured to the LED surface or to the frame?
Both exist and they differ, so say which one you mean. The front face of the LEDs and the structural wall are typically 80 to 150 mm apart, and that changes the arc your frame has to follow.
Why is the quote bigger than my own area calculation?
Because the screen covers the developed arc and the plan width you measured is the chord.
How many pieces should a curved LED video wall arrive in?
As many as the radius and the segment angle demand. Ask for the segment count and the angle per joint before you approve the shop drawing.
What goes wrong most often?
A frame built to the chord when the wall was measured on the arc, or a radius quoted against the wrong surface. Both stay invisible until delivery.
Send the three geometry figures, the wall height and the mounting method through our enquiry form, and we will confirm the segment angles before anybody cuts steel. Geometry is cheaper to fix on paper than on a low loader, and a curved LED video wall that fits the wall is the only kind worth ranking for.