GSM-7 vs Unicode SMS: Why Your Message Costs More Than You Expect
| Encoding | Single message | Each part of a long message |
|---|---|---|
| GSM-7 | 160 characters | 153 characters |
| Unicode (UCS-2) | 70 characters | 67 characters |
Why do long messages hold fewer characters per part? When a text is split into several segments, each one carries a small header so the phone can stitch them back together in order. That header uses a few bytes, reducing the space left for your words. You are normally billed per segment, not per text.
How one character changes the cost
Here is the catch. If even one character in the message falls outside GSM-7, the entire message switches to Unicode. A 120-character promotion that fit comfortably into one segment now exceeds 70 characters and is billed as two. A 300-character message might jump from two segments to five.
That is why a small decoration can double your costs across a large send. Send that campaign to 100,000 people and the difference is not small.
What triggers Unicode?
- Emoji. A smiley, a party popper or a thumbs-up all force Unicode, and many emoji count as two characters.
- Smart quotes and long dashes. Word processors and design tools silently turn straight quotes into curly ones (’ and “ ”) and hyphens into em dashes. They look innocent but are not in the basic GSM-7 set.
- Non-Latin scripts. Hindi, Bengali, Tamil, Arabic, Chinese and others always require Unicode.
- Some accented letters. Certain accents are supported in GSM-7, but many are not.
- Special symbols. Characters such as the tick mark, bullet point or trademark sign fall outside the set.
The extended character trap
GSM-7 also has an extended table with characters like the square brackets, curly braces, caret, tilde, backslash, the pipe symbol and the euro sign. They are allowed, but each one is counted as two characters because it needs an escape code. A message full of brackets or a euro price can run longer than your counter shows if you are not careful.
Should you ever use Unicode?
Yes, and sometimes you must. If your customers read Hindi or Bengali, a message in their own language will build trust and understanding that an English text cannot. The goal is not to avoid Unicode but to use it on purpose. In India, regional-language messages also have to follow DLT template rules, so register the exact text you intend to send.
For English campaigns, the choice is yours, and the economics are worth thinking through. An emoji may lift engagement for some audiences, but if it doubles your segment count, check that the extra response pays for the extra cost.
How to keep messages in GSM-7
- Draft in plain text. Write in a basic editor rather than pasting from a document that autocorrects punctuation.
- Replace curly quotes and dashes with straight quotes and simple hyphens.
- Skip emoji in high-volume, cost-sensitive campaigns.
- Preview before sending. Use your SMS platform’s segment counter, which shows the encoding and number of parts, and trust it over a word-processor count.
- Shorten links. A long tracking URL can eat half your first segment. Use a branded short link.
- Test dynamic fields. A customer name or product title pulled from your database may contain an unusual character that flips the whole message to Unicode. Sanitise or test variable content.
- Write tighter. The best fix is often editing. Cut filler and put the key action early.
Delivery and user experience
Segments are reassembled on the phone, and nearly all modern devices handle long messages smoothly. However, very long multi-part messages have more chances to arrive out of order or be delayed. Shorter messages are easier to read, quicker to act on and more likely to arrive cleanly.
A quick example
“Flash sale! Get 20% off today only – shop now: yourbrand.in/sale” looks like one clean message. But the dash is an en dash, which is not in GSM-7, so the whole message becomes Unicode and its limit drops to 70 characters. Replace the dash with a plain hyphen and the same message stays in GSM-7 with room to spare.
Want to cut SMS costs without losing impact? Our team can audit your templates, set up encoding checks in your SMS API and help you register regional-language content correctly. Contact us for a free review of your messaging spend.
