Guide
GSM-7 vs Unicode: why one character can double your SMS cost
An SMS is charged by the part, and the characters you use decide how much fits in a part. Paste your message into the counter below to see exactly what it will cost.
Try it: SMS part and cost counter
What the two encodings are
GSM-7 is the normal SMS alphabet. It has English letters, digits, common punctuation and some accented European letters. Each character takes seven bits, which is how 160 of them fit in one SMS.
Unicode (UCS-2 in the technical documents) can show almost anything, including emoji and every script. Each character takes twice as much room or more, so one SMS holds only 70.
An SMS uses one encoding for the whole message. It takes just one character outside GSM-7 to move all of it to Unicode.
How many characters fit
| Message size | GSM-7 | Unicode |
|---|---|---|
| 1 part | 160 | 70 |
| 2 parts | 306 | 134 |
| 3 parts | 459 | 201 |
| 10 parts (the most allowed) | 1,530 | 670 |
Past one part, each part holds 153 or 67 characters. That is why 161 characters cost the same as 306.
The characters that catch people out
Most of these are not typed on purpose. They arrive when text is copied from Word, a website or a phone keyboard that "improves" your typing.
| Character | What it is | What to do |
|---|---|---|
| ’ ‘ | Curly apostrophes and quotes | Use a straight ' from the keyboard |
| “ ” | Curly double quotes | Use a straight " or leave them out |
| … | The single-character ellipsis | Type three full stops |
| ŵ | The Chichewa letter w with a circumflex | Use plain w if your readers accept it |
| 😀 | Any emoji | Leave it out. It is also 2 units on its own |
Chichewa and SMS length
Good news first: everyday Chichewa uses the same letters as English, so Moni and Zikomo cost no more than Hello and Thank you. Two details deserve care.
- The letter ŵ. You may know it from the older spelling Malaŵi. It is not in GSM-7, so a single ŵ makes the whole message Unicode. If your readers are happy with plain w, use it.
- The apostrophe in ng'. Words like ng'ombe are fine with a straight apostrophe. Word and some phones swap it for a curly one, which is not in GSM-7. Paste the text into the counter above to check.
Chichewa words also tend to run longer than their English versions, so a translated message may need two parts. Count it before you send, and have it read by a fluent speaker. There is more on this for churches and health programmes.
Two characters that count double
A few characters are in GSM-7 but take two places each: ^ { } \ [ ] ~ | €. They do not switch the message to Unicode, but they use up your 160 faster.
Keeping a message in one part
- Write it in the dashboard, or in a plain notes app, not in Word.
- Remember that merge fields change the length: a long name can push a message over the limit for one person and not for others.
- Cut greetings and repeated words before you cut the facts people need.
- Check the final part count on the review screen before sending. See pricing for what each part costs.
Questions
How many characters are in one SMS?
Up to 160 in GSM-7, the normal SMS alphabet, or up to 70 in Unicode. When a message is longer it is split into parts of 153 or 67 characters, because each part needs a little room to be joined back together.
Why was I charged for two messages?
Your message went over the limit for one part. Long messages are sent as several parts, each part is charged, and the phone shows them as one message. Check for a hidden Unicode character if it looks short.
Can I write in Chichewa?
Yes. Chichewa mostly uses letters that are in GSM-7, so normal text costs the same as English. Only the letter ŵ, and curly apostrophes in words like ng'ombe, switch the message to Unicode.
Does SMS YANU change my characters for me?
No. Your message goes out as you wrote it. The dashboard shows the encoding and part count while you type, so you can decide whether to change it.
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