Origins: a tool born on the factory floor
The QR code (short for Quick Response code) was invented in 1994 by Masahiro Hara, an engineer at Denso Wave, a Toyota subsidiary. The problem he was solving: tracking car parts along production lines faster than one-dimensional barcodes, which were running out of room.
The big advantage: a QR code holds up to 100 times more data than a standard barcode, and it reads in any orientation. Denso Wave deliberately chose not to charge for the licence — a rare move that opened the door to worldwide adoption.
How it works, technically
A QR code is made up of small black and white squares (the "modules") arranged in a grid. Three large squares in the corners tell the reader which way is up — that's why your phone can decode it even when you hold the device at an angle.
There are four encoding modes:
- Numeric: up to 7,089 digits
- Alphanumeric: up to 4,296 characters (letters, digits, basic punctuation)
- Binary / byte: up to 2,953 bytes — this is the mode that carries a full URL
- Kanji: up to 1,817 Japanese characters
A restaurant menu uses binary mode, which carries a URL along the lines of https://restaurant.qrmenupro.com/your-restaurant.
Error correction: the hidden stroke of genius
Four levels of redundancy are available:
- L (Low): 7% of the code can be damaged and it still reads
- M (Medium): 15%
- Q (Quartile): 25%
- H (High): 30%
In plain terms: a level H QR code still scans even if 30% of its surface is stained, torn or covered by a logo in the middle. That's exactly what lets you brand a QR code with your restaurant logo without breaking it.
"A QR code with H-level correction survives a drop of sauce, a creased corner, even a logo in the centre. That's why it holds up so well on a placemat." — A food design studio in Lyon
Uses in a restaurant: well beyond the menu
1. Showing the menu
The most common use: a QR code on the table that opens the digital menu. Multilingual, with allergens, photos and up-to-date prices.
2. Taking payment
Some restaurants use a direct payment QR code (PayPal, or an instant bank transfer link). The customer scans, pays in three taps, and the server confirms.
3. Collecting reviews
A small QR code on the receipt that opens your Google Reviews or Tripadvisor page. Restaurants that do this typically see review volume rise by 200% to 400%.
4. Building loyalty
A loyalty QR code (digital card, points, discounts) on the placemat or the front window. The customer signs up, you get their email address, and you have a way to reach them.
5. Taking bookings
A QR code in the window, readable late at night, that opens your booking system. Passers-by can reserve a table even when the dining room is closed.
Design best practices
Minimum size
On a table-top item, a QR code needs to be at least 2.5 cm × 2.5 cm (about 1 inch square) to scan comfortably from 20-30 cm away. In an outside window, allow 8 to 10 cm (3 to 4 inches) so it can be scanned from the pavement.
Colours
Black on white is still the most universal and the easiest to read. If you want to customise it, keep a contrast ratio of at least 4:1 between the modules (dark colour) and the background (light colour). Never invert it to light on dark — a lot of scanners struggle with that.
Centre logo
Possible with H-level correction, covering no more than 20% of the surface. Keep it properly centred, and never let it overlap the position squares (the three large corner squares). Put a white background behind the logo so the code stays clean.
Quiet zone
A QR code needs a white border around it to be read: at minimum the equivalent of 4 modules (four of the small squares). Never butt your QR code up against the edge of a block of text or an image.
Key takeaways
- QR code invented in 1994 by Denso Wave (Toyota), licence-free
- Binary mode is what encodes menu URLs
- Error correction covers up to 30% surface damage (level H)
- Uses: menu, payment, reviews, loyalty, bookings
- Minimum size: 2.5 cm indoors, 8-10 cm in a window
- Colours: dark on light, 4:1 contrast minimum
- Centre logo possible up to 20% of the surface
- Quiet zone (white border) is non-negotiable