A Guide to Bulk SMS Character Limit & Cost
If your message uses only plain English letters and common punctuation, one SMS = 160 characters. If it has any regional script (like Hindi) or an emoji, it becomes Unicode and one SMS = 70 characters.
When SMS length is longer than 160, it gets split into multiple parts (called concatenated SMS) and each part can hold fewer characters (153 for GSM‑7, 67 for Unicode).
How encoding changes Per SMS Cost
You composed a message and it is costing more than you thought. That’s usually because of encoding.
GSM‑7
You write a normal English message with periods, commas, numbers. It usually stays in GSM‑7.
GSM‑7 gives 160 characters in one SMS. If you go past that, extra parts are 153 characters each. Use plain characters to save credits.
- 160 = 1 SMS
- 161–306 = 2 SMS (153 each)
- 307–459 = 3 SMS
- 460–612 = 4 SMS
Example – Plain English (GSM‑7)
- Text: “Your OTP is 123456. Do not share it.”
- Length: 33 chars → 1 SMS (GSM‑7)
Unicode
You write in Hindi, Tamil, or add an emoji. That forces Unicode.
Unicode gives 70 characters in one SMS. Extra parts are 67 characters each. Unicode messages usually cost more.
- 70 = 1 SMS
- 71–134 = 2 SMS (67 each)
- 135–201 = 3 SMS
- 202–268 = 4 SMS
Example – Hindi (Unicode)
- Text: “आपका OTP 123456 है।” → Unicode → counts against 70/67 limits
How SMS concatenation work?
When an SMS is too long, the gateway breaks it into parts. Each part includes a small header to help phones reassemble the message, which reduces the usable character count per part.
| Encoding | Single SMS limit | Per concatenated part |
|---|---|---|
| GSM‑7 | 160 | 153 |
| Unicode | 70 | 67 |
Different SMS providers sometimes fix or change characters. Always do a small test batch with the exact message before you do large campaign.
Simple tips to save money and get better delivery
- Use plain characters (straight quotes, simple hyphens) if possible – They stay in GSM‑7.
- Don’t use emojis in high‑volume messages.
- Shorten long links with a link shortener.
- Keep OTPs and confirmations to one segment.
- If you send in regional languages, make separate lists for each language – don’t mix.
- Cut unnecessary words in your SMS. Shorter messages cost less and often read better.
Small edits – like replacing a curly quote with a straight one can save money when you send large batches.
FAQ (People Also Ask)
Q: How many characters in one SMS?
A: 160 for GSM‑7; 70 for Unicode.
Q: What makes an SMS switch to Unicode?
A: Any character not in GSM‑7, like regional scripts, many punctuation marks, and emojis.
Q: Why do concatenated SMS use fewer chars per part?
A: Each part includes a small header to help phones reassemble the message, which reduces the usable character count per part.
Q: Can I mix languages in one SMS?
A: Yes, but if you include a non‑GSM script, the whole message becomes Unicode and costs more.
Q: How do I check my SMS character count?
A: Use your gateway’s composer, a simple text editor, or the calculator below before sending.
