Understanding the 160-Character SMS Limit
SMS (Short Message Service) has a hard limit of 160 characters per message. This limit comes from the GSM standard used by cellular networks worldwide. When you send a message longer than 160 characters, it's automatically split into multiple SMS messages.
The Cost of Long Messages
- 160 characters = 1 SMS
- 161–320 characters = 2 SMS
- 321–480 characters = 3 SMS
- And so on...
If you're sending bulk SMS (marketing, notifications, alerts) via an API service like Twilio or AWS SNS, you pay per SMS. A 300-character message costs twice as much as a 160-character message. This tool helps you optimize message length to control costs.
GSM-7 vs Unicode (UCS-2)
Standard Characters (GSM-7)
Basic Latin letters, numbers, spaces, and common punctuation are encoded using GSM-7. These characters count as 1 each and allow the full 160-character limit.
Allowed characters: A-Z, a-z, 0-9, space, . , ? ! ' " $ ¥ ¤ € @ # ¢ £ ¥ ¿ ¡ § ¶
Special Characters (Unicode / UCS-2)
Accented letters (é, ü, ñ), emoji, or non-Latin alphabets (Chinese, Arabic, Cyrillic) require Unicode encoding. When you include ANY Unicode character, the entire message switches to UCS-2 encoding, which reduces the limit to 70 characters per SMS.
Examples: "Café" = 1 SMS with 70-char limit (not 160). An emoji = 1 SMS with 70-char limit.
Practical Examples
Example 1: English Message
"Hi, just checking in. How are you doing? Let me know when you're free to chat."
Length: 79 characters
Encoding: GSM-7
Cost: 1 SMS
Example 2: Message with Emoji
"Great news! 🎉 We're hiring. Apply now!"
Length: 42 characters
Encoding: Unicode (emoji forces UCS-2)
Limit: 70 characters per SMS
Cost: 1 SMS, but only 42/70 characters used
Example 3: Message with Accented Character
"Thanks for your interest in our services!"
vs.
"Merci for your interest in our services!" (assuming French "Merci" with accent)
Cost difference: The accented version costs as 70-char SMS (not 160), wasting 40+ characters of potential content.
Tips for SMS Optimization
1. Keep Messages under 160 Characters
This is the most cost-effective way to send SMS. Use this counter to stay just under the limit.
2. Avoid Emoji
Emoji are engaging but expensive. They force Unicode encoding, cutting your limit to 70 characters. Use sparingly or not at all for bulk messaging.
3. Avoid Accented Characters When Possible
If you're sending to international recipients, plain ASCII (no accents, no special characters) is safest and cheapest.
4. Use Abbreviations
"Thx" instead of "Thanks" (saves 3 chars). "Pls" instead of "Please" (saves 3 chars). "Yr" instead of "Your" (saves 2 chars). These add up.
5. Remove Unnecessary Words
"Meeting at 3pm Tuesday" (23 chars) instead of "We have a meeting scheduled for 3pm on Tuesday" (48 chars).
6. Use Short Links for URLs
A full URL like "https://www.example.com/promotions/summer2024" (46 chars) can be shortened to "bit.ly/sum24" (12 chars) using a URL shortener. Saves 34 characters.
SMS Segmentation Costs
If you're using a bulk SMS provider (Twilio, AWS SNS, MessageBird, Brevo):
| Message Length | SMS Segments | Cost @ $0.01/SMS |
|---|---|---|
| 160 characters | 1 | $0.01 |
| 320 characters | 2 | $0.02 |
| 480 characters | 3 | $0.03 |
| 1,000 characters | 7 | $0.07 |
Cost optimization: Reducing a message from 300 to 160 characters cuts the SMS cost in half.