QR code poster scanning distance: open your menu from across the road

Start with QR code poster scanning distance

A cafe puts a poster on the wall that faces the road. The QR code on it opens the menu page. The person who needs to scan it is on the far pavement, waiting to cross. Getting the QR code poster scanning distance right is the whole job. It starts with a tape measure, not a design file.

Measure from where people will really stand to the wall. A two-lane road with pavements is often 8 to 12 metres from wall to wall. A narrow lane is closer to 5 metres. Write the number down before you open any software.

The ten-to-one rule, metres to millimetres

Phone cameras read a code well when it is about one tenth as wide as the distance to it. So the sum is short. Take the distance in metres and multiply by 100. That gives the code width in millimetres.

At 2 metres, the code needs to be 200 mm wide. At 5 metres, it needs 500 mm. At 10 metres, it needs 1000 mm, which is a full metre of code.

That last figure is where most posters fall down. An A1 poster is 594 mm wide. An A0 is 841 mm. A code read from across a wide road will not fit on a standard poster with room left for anything else.

What to do when the road is too wide

There are two honest answers. The first is a bigger print. A banner or a window vinyl can carry a code of 800 mm or more on its own. That works on a shop front with a large window and plain glass behind it.

The second is to move the code to where people stop. Let the poster carry the big words: the cafe name and "Menu inside" in letters 150 mm tall, easy to read from the far side. Then put a second, smaller code at the door or on the A-board on the pavement. People read that one from about 1.5 metres, so a 150 mm code is plenty. The poster pulls people across. The code at the door opens the menu.

Many cafes do both. The large code catches people waiting at the crossing. The small one catches people who have already walked over.

Fewer modules, bigger squares

A QR code is a grid of small squares called modules. The more data the code carries, the more modules it needs. At the same printed width, more modules means each one is smaller. Small modules are what a distant camera fails to read.

A long web address with tracking text makes a dense code. A short address makes a sparse one. A dynamic QR code helps here. The code opens a short redirect address, and that address sends the phone on to the menu page. The pattern stays small and coarse. You can also re-point it to a new menu later without reprinting the poster.

As a guide, take a code 25 modules across, printed 500 mm wide. Each module comes out at about 20 mm. That reads well at 5 metres in daylight. The same width with 57 modules gives under 9 mm per module, and the scan becomes slow or fails.

Keep the quiet zone clear

The quiet zone is the plain margin round the code. Scanners use it to find where the code starts and stops. The usual rule is four modules of clear space on every side.

On a 500 mm code with 25 modules, one module is 20 mm. So the quiet zone is 80 mm on each side, and the full block of code plus margin is 660 mm wide. Plan the layout around that block, not around the code alone.

Do not let a photo, a border line or the edge of the poster run into that margin. Do not put the cafe logo over the corners. The three big squares in the corners are how the phone finds the code. Covering any of them stops the scan.

Contrast in plain words

Print dark squares on a light ground. Black on white is best. Dark brown or deep navy on cream also works, as long as the dark is truly dark.

Skip light colours on light paper, such as grey on white or yellow on cream. Skip a light code on a dark ground too, because many phone cameras read it badly or not at all. Do not print the code over a photo or a pattern. If the poster is busy, give the code a solid white panel of its own.

Here is a quick test. Print the code in your chosen colours and take a photo of it. Turn the photo to black and white. If the code still looks crisp and the dark parts are clearly dark, the contrast is fine.

Matte paper, not gloss

A poster across the road catches the sun in the afternoon and the street lights at night. Gloss paper turns that light into a white flash, and the flash often sits right on the code. The phone sees a blank patch.

Ask the printer for matte stock or a matte laminate. For an outdoor wall, a 170 to 200 gsm matte paper inside a frame lasts a few months. For a longer run, matte vinyl or a poster board with matte lamination stands up to rain and sun better. If the poster goes behind glass, the glass will reflect too. Set the code lower on the sheet, away from the glare line, and test at the hours people pass.

Proof at full size, then test from the pavement

Before the full print, run a proof of the code at its real size. A large-format printer can print just the code block on one sheet. Tape it to the wall where the poster will go.

Then cross the road and stand where people wait. Try three phones: one new, one a few years old, and one with a scratched camera lens. Open the camera app, point it and count. A good code opens the menu in under two seconds. If it takes longer, make the code bigger, shorten the address, or move the code closer to people.

Test twice, once at midday and once after dark. A code that reads at noon can fail under a yellow street light if the contrast is weak.

Put words beside the code

People across the road do not know what the code opens until you tell them. Print a short line beside it, large enough to read from where they stand, such as "Scan for today's menu". At 8 metres, letters need to be about 80 mm tall to read easily.

Keep the menu page light. It should load fast on mobile data and put the dishes and MRP prices near the top, with a call button and a map link close by. The code only opens the page. The page has to do the rest.

Getting the code ready for print

You can get a dynamic code for your menu at buyqrcode.com and print it at whatever size your tape measure gives you. Use the vector file, such as SVG or PDF, rather than a small image, so the edges stay sharp at 500 mm or a full metre. If you plan to re-point the code to a seasonal menu, set the menu address up before the poster goes to the printer, so the first scan on the first day opens the right page.