What Are Message Segments and Why Do They Matter?
If you’re sending SMS announcements for your business, you’ve probably focused on writing short, punchy messages that drive action. But there’s a technical detail under the hood that affects your delivery costs, performance, and even message formatting: SMS message segmentation.
In this article, we’ll explain what SMS segments are, how they work, and what marketers need to know to avoid unnecessary costs while still creating compelling, on-brand messages.
What Is an SMS Segment?
An SMS segment is the number of character “chunks” your message is broken into before it’s sent over the mobile network. Mobile carriers have a limit on how much text can be included in a single SMS — if your message is too long, it’s split into multiple segments automatically.
Each segment adds to your billing count and can affect how the message appears to the recipient.
Segment Length Depends on Encoding
The two main SMS encoding types directly impact how many characters fit into a single segment:
| Encoding Type | Characters per 1 Segment | Characters per Segment (Multipart) |
|---|---|---|
| GSM-7 | 160 characters | 153 characters |
| Unicode (UCS-2) | 70 characters | 67 characters |
Learn more about SMS encoding.
How Multipart SMS Works
When your message exceeds the segment limit (160 for GSM-7 or 70 for Unicode), it becomes a multipart message. That means:
Your message is broken into chunks.
Each chunk is sent separately with headers that help phones reassemble them.
The character count per segment is slightly reduced to allow room for this header (153 or 67 characters per segment).
Example: A 325-character GSM-7 message = 3 segments (153 + 153 + 19)
Why Segments Matter to Your Business
1. More Segments = More Cost
The sender is charged per segment, not per message. That means a message with 2–3 segments can double or triple your cost per send.
2. Multipart Delivery Risks
Sometimes multipart messages may arrive:
Out of order
With slight delays
Missing formatting consistency
This can negatively impact urgent or time-sensitive campaigns.
3. User Experience
Long messages may get truncated or split awkwardly. Keeping messages within 1 segment improves clarity and engagement.
Tips to Minimize SMS Segments
Use character counters. Utilize online tools that will show you how many segments your message uses in real time.
Avoid emojis unless they’re essential. Emojis switch your encoding to Unicode, shrinking your usable characters per segment.
Don’t copy and paste from Word or Google Docs. These tools often use curly quotes and hidden special characters that force Unicode encoding.
Use link shorteners. Long URLs take up a lot of space — use branded or third-party shorteners (like Bit.ly or Rebrandly) to save room.
A/B test shorter copy. Sometimes, saying less increases conversion — and saves on segments.
Segment Counts and Cost Planning
Most marketing teams overlook segments when budgeting for SMS campaigns. Here’s a quick cost scenario:
Campaign A: 100,000 recipients, 1 segment each → 100,000 segments
Campaign B: 100,000 recipients, 3 segments each → 300,000 segments
That’s a 3x cost increase for essentially the same message, just a little longer.
Understanding how segment math works gives you better control over campaign performance and spend.
Summary: Smart SMS Campaigns Start With Segment Awareness
Segments matter. They affect how your message is sent, how much you pay, and how your users experience it.
Before you hit send:
Check your character and segment count.
Watch out for encoding changes from special characters.
Stay concise and clear for better deliverability and ROI.
By designing campaigns with SMS segmentation in mind, you’ll create messages that are not only cost-effective but also more impactful.
Need help optimizing your next SMS campaign?
Get in touch — our team can help you craft messages that perform better, cost less, and reach more people