# What is the optimal QR code size on screen?

One of our clients requests us to put a QR code to his contacts page, and I would like to get to know what is the optimal size for a QR code on screen. (in px) - considering that the average screen resolution is around 1366x768 px.

I want to make sure that phones will be able to read the code.

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There are several factors: How far away from the screen will the QR reader be? How dense are the QR codes? (simple URLs will be less dense, but complex content QR will be very dense requiring a larger code in order to be legible to readers). – JonW May 8 '12 at 12:43
1. I can't tell how far the QR reader will be, but is suppose it to be like 5-20 cm-ers, since most users sit close to the screen. 2. The QR code will contain a phone adress, e-mail adress, name, etc (business card info) – Roland Pokornyik May 8 '12 at 12:46

It will depend on how much information the QR code has to convey and how far away the scanner is from the image. This page has some calculations based on the number of elements in the QR code, the number of characters and the scan distance.

So for a code with 45 "modules", 125 characters being scanned at 300mm you'd need an image that was 27mmx27mm square.

Use that table to calculate the minimum size and then increase it a bit to cope with people trying to scan further away.

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This is the most reasonable formula I've seen for sizing QR codes. It boils down to `width = expected distance/scale factor` (scale factor should be between 6 (largest) and 10 (smallest)). The following assumes that users are (worst case) 36 inches from the computer screen and that the screens have ~ 100 ppi.

For your case this would work out to: `width = 36 in/6 = 6 in ~ 600 px` or `width = 36 in/10 = 3.6 in ~ 360 px`

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