Comparisons
Static vs Dynamic QR Codes
What the redirect actually buys you, measured on real encoded codes, and which payloads are worse off for it.
16 min readSMS QR Code Generator
Scan it and a text message opens, addressed to you, with the wording already typed. The sender reads it and presses send.
Write the message. A code that opens a blank text asks somebody to compose something, and most people will not.
Download your QR code
Your code appears here as you type.
There Are Two SMS Formats, and They Are Not Equal
This is the part no other generator page mentions. An SMS payload has two spellings in the wild, and which one a tool picks decides whether your prefilled message survives the trip.
| Format | What it looks like | Where it came from | In practice |
|---|---|---|---|
| SMSTOWhat we encode | SMSTO:+447700900123:TABLE 12 | The mobile-tagging convention, predating the RFC and built into most scanner apps. | Handled most consistently by phone cameras, and needs no percent-encoding, so the code stays smaller. This is what the tool encodes. |
| sms (RFC 5724)Not used here | sms:+447700900123?body=TABLE%2012 | The IETF standard, published in 2010. | Correct on paper, and the body parameter is dropped by some Android messaging apps. The percent-encoding also makes it longer for the same message. |
One consequence is worth knowing. Because SMSTO separates the number from the message with a colon, a message that itself contains a colon relies on the scanner splitting on the first one only. Most do. A scanner that splits on every colon will truncate your message, which is a scanner bug rather than an encoding one, but it is your poster that looks broken.
What the Message Costs in Printed Millimetres
The message is stored inside the code, so a longer one is a physically larger sticker for the same readability. Under 160 characters also keeps it to a single text for whoever sends it.
| What you enter | What the scanner reads | Version | Modules | Print at least |
|---|---|---|---|---|
| Number onlyOpens a blank text to you. Smallest version of this code. | SMSTO:+44770090012319 characters | 1 | 29 | 11.6 mm |
| With a short prefilled messageThe useful shape. The sender does not have to think of anything. | SMSTO:+447700900123:TABLE 1228 characters | 2 | 33 | 13.2 mm |
| With a reference codePrefilled text is how a text message becomes a one-tap status update. | SMSTO:+447700900123:JOB 4471 arrived on site44 characters | 3 | 37 | 14.8 mm |
| With a full messageOver 100 characters. Compare the print width with the first row. | SMSTO:+447700900123:Hello, I saw your sign and I would like to book a viewing for the property this week if anything is available.130 characters | 8 | 57 | 22.8 mm |
A short reference beats a polite sentence every time. You are not writing to the recipient, you are writing what the sender is willing to put their name to. If the reply needs more room than a line, an email code gives people a subject line and a keyboard, and a phone code prints smaller than either.
What This Does Not Do
- It does not send anything. The message opens as a draft under the sender's own number, and they choose.
- It costs the sender whatever a text costs them. Say so on the poster if you are asking the public to use it.
- No MMS, no images, no group threads. One number, one message.
- For a chat thread instead of a text message, the WhatsApp tool does the same job over the internet, with no per-message cost to the sender.
- Static, so the number is fixed once printed.
SMS QR Code Questions
What happens when someone scans an SMS QR code?
Their messaging app opens a new text to your number, with your message already typed if you set one. Nothing sends until they press send, so the person always sees what is going out under their name.
Why does the code say SMSTO instead of sms?
Two formats exist. SMSTO is the older convention and phone cameras handle it most consistently, and it needs no percent-encoding so the code stays smaller. The RFC 5724 sms: form is more correct on paper, and some Android messaging apps drop its prefilled body.
Can I prefill the text message?
Yes, and it is the main reason to use one of these. A prefilled reference, table number or job code turns a text message into a single tap, which is what makes people actually send it. Keep it under 160 characters so it stays one message.
Does the person get charged for the text?
They send it from their own number on their own plan, so it costs whatever a normal text costs them. That is worth saying on the poster if you are asking members of the public to use it.
Do I need a country code in an SMS QR code?
Yes, for anybody outside your country. Without a leading plus and the country code the number only resolves on that national network. The tool warns you when the number is missing one.
More for work and admin
Contact cards, Wi-Fi, and forms people fill in.
- Google review QR codeThe review link forms measured side by side, including the one that opens the star form rather than the listing.
- Google Form QR codeTurn a Google Form link into a code that scans, and see which of your two links prints smaller.
- Wi-Fi QR codeShare a network without reading the passphrase aloud, with the separator characters escaped properly.
Guides worth reading
All guides- Printing
QR Code Sticker Size: The Circle Costs You 30%
The usable square inside a round sticker is 70% of its diameter. Measured minimum sizes for real links, against every common sticker size.
8 min read - Reference
Offline QR Code Generators for Every Device
What each platform already ships, the measured cost of each payload type, and how to check an offline claim yourself.
26 min read
