An SMS can hold 160 characters — but only when the text uses GSM-7 encoding and fits within one segment. Longer copy, emoji and certain special characters can change both the capacity and the number of SMS segments sent. That affects cost even though the recipient may see one joined message.
In brief: 160, 153, 70 and 67
| Encoding | One segment | Multiple segments |
|---|---|---|
| GSM-7 | Up to 160 characters | Up to 153 characters per segment |
| Unicode / UCS-2 | Up to 70 characters | Up to 67 characters per segment |
When a message is split, every segment needs a small amount of technical information so that the handset can reassemble the parts. The limit therefore falls from 160 to 153 characters for GSM-7 and from 70 to 67 for Unicode-based messages.
What is GSM-7?
GSM-7 is the compact standard character set used for many common letters, numbers and symbols in SMS. Text containing only these characters can hold up to 160 characters in one segment.
Some characters in the GSM-7 extension table occupy two character positions even though they appear as one. Common examples include ^, {, }, , [, ], ~, | and €. An ordinary character counter in a writing application cannot therefore always calculate SMS length accurately.
When is Unicode or UCS-2 used?
If the copy includes a character that cannot be represented in GSM-7, the whole message will normally use a Unicode-based SMS encoding. Capacity then falls to 70 characters in a single segment or 67 characters per segment in a longer message.
Emoji, many non-Latin writing systems, typographic quotation marks and certain special symbols can trigger this change. An emoji can also occupy more than one code unit. Testing the completed message is more reliable than estimating it from the number of visible symbols.
Why does one message become several billable segments?
A GSM-7 message of 160 characters fits in one segment. Add one ordinary GSM-7 character and the 161-character message has to be split into two segments, each with a capacity of 153. Similarly, a 71-character Unicode message will normally become two segments with a capacity of 67 each.
The handset usually joins the parts and displays one message. They remain separate SMS segments during delivery. Intellipush pricing depends on the segments sent and their destination. See the pricing page for the payment model and indicative destination examples.
Small edits can make a large difference
Copy can sit just below the GSM-7 limit and still jump to several segments when a typographic symbol or emoji is inserted. This often happens when content is pasted from a writing tool that uses smart quotation marks or an em dash.
You do not always need to remove these characters. Emoji and correct language may be important to the message. The point is to understand the effect on segment count before the send is approved.
How to control length and cost
- Finish the copy with every personalisation field and link included.
- Test the longest realistic version, not only a template containing short examples.
- Check the encoding and identify any character that triggers Unicode.
- Review the number of segments, not only the visible character count.
- Multiply segments by recipients and the relevant destination price.
- Test on phones you control before a larger send.
Use the SMS length calculator
Paste the finished copy into the SMS length calculator. It shows the encoding, characters and segments so you can compare versions before sending. You can then use the SMS cost estimator for an overall estimate.
Remember that a link, recipient name or other dynamic content may make the real message longer than the example. Test the workflow using realistic data, and treat the current portal price at purchase as authoritative.
A relevant next step
Choose the right working method
Compare the portal, API and tools before deciding how SMS should fit in.
