What is Character Limit (SMS)?

Understanding the SMS Character Limit: The Basics

Before we get into the technical details, let’s establish what the SMS character limit is and why it even exists.

What Exactly is the SMS Character Limit?

The SMS character limit refers to the maximum length, measured in characters, that a single standard text message can contain. When you type a message on your phone or through an SMS platform, there’s a cap on how long that individual message part can be before it either gets cut off or, more commonly, split into multiple messages. This constraint has been a fundamental part of SMS technology since its inception.

Why Does This Limit Exist? A Brief History

The character limit isn’t arbitrary. It dates back to the 1980s when SMS was developed alongside the Global System for Mobile Communications (GSM) standards. Here’s a quick look at the reasons:

• Technical Efficiency: Early mobile networks had very limited bandwidth. SMS was designed to be a lightweight, efficient way to send short pieces of information without congesting these networks.
• Signalling System No. 7 (SS7): SMS messages were cleverly designed to travel on the SS7 network’s signaling pathways, which were already used by telephone networks to set up and manage calls. These pathways had small data packet sizes, influencing the message length.
• Postcard Analogy: The developers, like Friedhelm Hillebrand, noted that postcards and telex messages often contained fewer than 160 characters. This observation helped justify the limit as sufficient for brief communications.

The goal was to create a system that was reliable and could deliver short, quick messages efficiently.

The Magic Number: 160 Characters (Usually)

You’ll almost always hear the standard SMS character limit referred to as 160 characters. This is true when your message uses a specific type of character encoding called GSM-7, which we’ll explore next. If you stick to the characters within this set, you can fit 160 of them into one standard SMS segment.

The Technical Nitty-Gritty: GSM-7 vs. UCS-2 Encoding

The actual number of characters you can fit into a single SMS segment (that 160-character benchmark) depends heavily on the character encoding used. This is where things get a bit more technical, but it’s crucial for understanding how your messages are handled.

GSM-7 Character Set

• What it is: The GSM 03.38 character set, commonly known as GSM-7, is a 7-bit character encoding standard. It was specifically developed for use in GSM mobile networks for SMS messages.
• Characters included: GSM-7 includes most characters you’d commonly use in English:
  • Basic Latin uppercase letters (A-Z)
  • Basic Latin lowercase letters (a-z)
  • Digits (0-9)
  • Common punctuation marks (e.g., . , ! ? ‘ ” @ # % & * ( ) + – / : ; = < >)
  • Some common symbols (e.g., $, £, €)
  • A few Greek letters (e.g., Δ, Φ, Γ, Λ, Ω, Π, Ψ, Σ, Θ, Ξ)
  • Special characters like space, newline, and carriage return. It’s important to note that some seemingly common symbols (like ^ { } [ ] ~ \ |) are part of an “extended” GSM-7 set and actually take up two GSM-7 characters (an escape character plus the symbol itself).
• How it achieves 160 characters: SMS messages are technically constrained to 140 octets (which is 1120 bits) of data. Since each GSM-7 character is encoded using 7 bits: 1120 bits/7 bits per character=160 characters This is why, when you use only these standard characters, you get that 160-character limit per SMS segment.

UCS-2 (and UTF-16) Character Set

What happens when you want to use characters not found in the basic GSM-7 set, like emojis 😊, accented letters (é, ñ, ü), or characters from non-Latin alphabets (e.g., Cyrillic, Arabic, Chinese, Japanese)? That’s where UCS-2 comes in.

• What it is: UCS-2 (Universal Character Set coded in 2 octets) is a 16-bit character encoding that can represent a much wider range of characters from languages all over the world, plus many symbols and emojis. UTF-16 is a broader standard that encompasses UCS-2. For SMS, they effectively mean the same thing regarding character limits.
• When it’s used: If your SMS message contains even a single character that is not part of the GSM-7 standard set (like an emoji 😂 or an accented letter like ‘á’), the entire message must typically switch to UCS-2 encoding to support that character.
• The impact on character limit: Because each character in UCS-2 encoding takes up 16 bits (instead of 7 bits like GSM-7), the maximum number of characters you can fit into that same 1120-bit data payload drops significantly: 1120 bits/16 bits per character=70 characters So, simply adding one emoji or one non-GSM-7 letter can reduce your single SMS segment limit from 160 characters down to just 70 characters. This is a huge difference and a common surprise for those new to SMS marketing.

How to Know Which Encoding is Being Used?

• Automatic Detection: Most modern SMS platforms and sending tools automatically detect the presence of non-GSM-7 characters in your message. They will then switch the encoding to UCS-2 and adjust the displayed character count and segment limit accordingly.
• Manual Check: It’s crucial to pay attention to the characters you’re typing. If you need to maximize your message length within a single 160-character segment, be vigilant about avoiding emojis or special symbols that aren’t in the GSM-7 set.
• Online Tools: Several free online tools can analyze your text and tell you if it contains any non-GSM-7 characters and what the resulting encoding and segment length would be.

GSM-7 vs. UCS-2 Comparison

Feature	GSM-7 Encoding	UCS-2 Encoding
Bits per Character	7 bits	16 bits
Chars per Segment	160 characters	70 characters
Common Characters	Basic Latin letters, numbers, common punctuation	All GSM-7 + emojis, accented letters, non-Latin alphabets
Use Case	Standard English texts, maximizing length	Multilingual texts, messages with emojis/symbols

Message Concatenation: Sending Longer Texts

So, what happens if your message absolutely needs to be longer than 160 (or 70) characters? You don’t have to send multiple completely separate texts. Instead, SMS concatenation comes into play.

What is SMS Concatenation?

SMS concatenation is a clever technical process that allows a long text message (one that exceeds the character limit of a single SMS segment) to be automatically split into multiple smaller segments by the sending platform. These individual segments are then sent to the recipient’s mobile device, where the handset reassembles them in the correct order to display as one single, continuous long message to the user.

So, from the recipient’s perspective, they usually just see one coherent message, even if it was technically delivered in several parts.

How Concatenation Works

The magic behind concatenation lies in a small piece of information called the User Data Header (UDH).

• User Data Header (UDH): When a message is concatenated, a few bytes at the beginning of each SMS segment are reserved for the UDH. This header contains information that tells the receiving phone:
  • That this segment is part of a concatenated message.
  • The total number of segments in the message.
  • The sequence number of this particular segment.
• Impact of UDH on Segment Length: Because the UDH takes up some of the 1120 bits available in each segment’s data payload, the actual number of characters you can fit into each concatenated segment is slightly less than the limit for a single, non-concatenated message.
  • For GSM-7 encoded messages: Each concatenated segment is typically reduced from 160 characters to around 153 characters.
  • For UCS-2 encoded messages: Each concatenated segment is typically reduced from 70 characters to around 67 characters.

So, if you write a GSM-7 message that is 170 characters long, it will likely be split into two segments: the first containing 153 characters and the second containing the remaining 17 characters.

Implications of Concatenation

Using concatenated messages has a few important consequences:

• Cost: This is the big one. You are typically billed by your SMS provider for each segment sent. So, a message that is split into three segments will cost you three times as much as a message that fits into a single segment. Understanding and managing message length is therefore crucial for controlling SMS campaign costs.
• User Experience: For the most part, concatenation is seamless for the end-user on modern smartphones and networks (as of May 16, 2025). They receive what appears to be one long message. However, on very old feature phones or in areas with poor network connectivity, there’s a small chance that segments could arrive out of order or that some segments might be delayed or even lost, leading to an incomplete or jumbled message. This is much less common now than it used to be.
• Deliverability: Generally, concatenation itself doesn’t directly cause deliverability failures. However, extremely long messages (e.g., 10+ segments) might sometimes face higher scrutiny from carrier filtering systems, or they might be more susceptible to partial delivery if one segment encounters an issue. It’s usually best practice to keep messages as concise as possible.

Impact of Character Limits on SMS Campaigns

The SMS character limit isn’t just a technical detail; it has a real impact on how you plan and execute your SMS campaigns.

Cost Implications

As mentioned, each SMS segment sent typically incurs a cost. If your messages consistently spill over into multiple segments, your SMS marketing budget will be consumed much faster.

• A message of 165 GSM-7 characters (2 segments) will cost twice as much as a message of 155 GSM-7 characters (1 segment).
• Adding a single emoji to a 100-character GSM-7 message could turn it into a 2-segment UCS-2 message (100 UCS-2 characters > 70 UCS-2 segment limit), potentially doubling its cost. Being mindful of character counts and encoding is therefore essential for budget management.

User Experience and Engagement

How does message length affect the recipient?

• Brevity is Often Better: Mobile users generally prefer SMS messages that are short, concise, and easy to read quickly. They’re often checking texts on the go.
• Avoid Overwhelm: A very long, multi-segment text message can feel overwhelming or intrusive on a mobile screen. Users might be less inclined to read it thoroughly.
• Get to the Point: Shorter messages that deliver key information or a clear call to action quickly tend to have better engagement rates.

Clarity and Readability

The character limit forces you to be disciplined with your writing.

• Focus on Clarity: You need to make every character count, which encourages clear and unambiguous language.
• Eliminate Fluff: There’s no room for unnecessary jargon, filler words, or rambling sentences in a well-crafted SMS. This constraint can actually lead to more powerful and effective communication.

Deliverability Considerations

While the character limit and concatenation are not primary causes of deliverability failure (like sending without consent or to invalid numbers), they can play a small, indirect role:

• Extremely Long Messages: Messages split into a very large number of segments (e.g., more than 5-6) might be more prone to issues like one segment failing, leading to an incomplete message for the user. Some carrier filters might also view unusually long concatenated messages with slightly more scrutiny, though this is less about the limit itself and more about unusual sending patterns.
• Formatting Issues: If special characters are mishandled and unexpectedly trigger UCS-2 encoding, leading to more segments than anticipated, it can cause formatting problems if the message breaks awkwardly. The main impact on deliverability is usually related to the content within those characters (spammy vs. valuable) and the consent of the recipient, rather than the length per se, assuming concatenation works correctly.

Best Practices for Working Within SMS Character Limits

Mastering the art of brevity is key to successful SMS marketing. Here are some best practices:

Plan Your Message Content Carefully

• Identify Your Core Message: Before you type a single character, know the one key piece of information or call to action you want to convey.
• Prioritize Ruthlessly: If you have multiple things to say, decide what is absolutely essential for the SMS and what could perhaps be communicated via a link to a landing page.

Be Concise and To-The-Point

This is where skillful writing comes in.

• Use Common Abbreviations (Judiciously): Abbreviations like “info” (information), “msg” (message), “appt” (appointment), “2FA” (two-factor authentication), “&” (and), “2” (to/too), “4” (for), “UR” (you are/your) can save space. However, avoid overly obscure or unprofessional abbreviations that might confuse your audience.
• Eliminate Filler Words: Cut out unnecessary words and phrases like “in order to,” “it is important to note that,” “due to the fact that.” Get straight to the verb.
• Use Numerals: Use digits (e.g., “5”) instead of spelling out numbers (“five”) to save characters.
• Focus on Strong Verbs: Active voice and strong verbs make messages more direct and concise.

Be Mindful of Special Characters and Emojis

Remember the impact on encoding and segment limits!

• The UCS-2 Switch: Adding even one emoji (😊) or a special character not in the GSM-7 set (like accented letters such as é, ñ, ü, or symbols like ™, ©, ®) will likely switch your entire message to UCS-2 encoding, reducing your single segment limit from 160 to 70 characters.
• Use Sparingly: If staying within a single 160-character GSM-7 segment is critical for cost or simplicity, use emojis and non-GSM-7 symbols very sparingly, or avoid them altogether.
• Test the Impact: Always check your SMS platform’s character counter to see how these characters affect your segment count and encoding type. Some modern emojis can even be multi-byte within UCS-2, taking up more than one “70-character equivalent” space.

Utilize URL Shorteners Wisely

Long URLs can eat up a significant portion of your character limit.

• Shorten Links: Use a URL shortening service.
• Use Branded or Custom URL Shorteners: Instead of generic public shorteners (like bit.ly, tinyurl), use a service that allows you to use your own custom short domain (e.g., yourbrnd.co/offer). This not only saves characters but also looks more professional, builds brand trust, and is less likely to be flagged as suspicious by carrier filters. Public shorteners are often associated with spam and phishing.

Preview and Test Your Messages

Never send blind.

• Use Platform Previews: Most SMS marketing platforms provide a real-time character counter and an estimate of the number of segments your message will use as you type. They often also indicate if the message is GSM-7 or UCS-2.
  • For example, when composing an SMS message within a WordPress environment using an integrated communication toolkit like Send by Elementor, users should look for these essential preview features. A well-designed interface within Send by Elementor would ideally provide a live character count, show the current segment number (e.g., “1/160” or “1/70”), and clearly indicate if a special character has switched the encoding from GSM-7 to UCS-2, dynamically updating the segment limit. This immediate visual feedback is invaluable for web creators and their clients to craft messages that are both cost-effective and clearly within desired length constraints, all without leaving their WordPress dashboard.
• Send Test Messages: Always send test messages to your own phone and, if possible, to devices on different mobile operating systems (iOS, Android) to check:
  • How the message displays.
  • If concatenated messages are reassembled correctly.
  • If links are working.
  • If special characters and emojis render as expected.

Use Landing Pages for More Detailed Information

If you have a lot of information to convey, SMS is often best used as a concise alert or a teaser.

• Include a short, compelling message in the SMS.
• Provide a link to a mobile-optimized landing page on your website where users can find more details, read full terms, or complete a more complex action.

Segment Your Audience for Relevance

Sending highly targeted and relevant messages often means you need less explanatory text or context, allowing you to be more concise.

Character Limits in Different Types of SMS Messages

How you approach the character limit might vary slightly depending on the type of SMS you’re sending.

Promotional Messages

For texts promoting sales, new products, or special offers:

• Brevity is King: You need to grab attention immediately. The message should be punchy, with a clear value proposition (the offer) and a strong call to action (CTA).
• Focus: Highlight the most compelling aspect of the promotion.
• Example: “SALE! 50% off all tees at [YourBrand] ends Sunday! Shop now: [yourbrnd.co/tees] Stop2End” (Concise, clear offer, CTA, link, opt-out).

Transactional Alerts (Order Confirmations, Shipping Updates)

These messages prioritize delivering essential information clearly.

• Key Details First: Include the most important information like order number, status update (e.g., “confirmed,” “shipped”), and any relevant links (e.g., tracking link).
• Can Be Slightly Longer if Necessary: While conciseness is still good, it’s more important to include all necessary transactional details to avoid customer confusion or follow-up inquiries. These might naturally extend to two segments if detailed shipping info or multiple items are listed.
• Example: “[YourBrand] Order #12345 Confirmed! We’ve received your order for 2x Blue Widget, 1x Red Gadget. Est. delivery May 20-22. Track: [yourbrnd.co/track12345]” (This might be close to or just over one GSM-7 segment).

Appointment Reminders

These must be clear and provide all critical details.

• Essential Info: Patient/client name (if appropriate), service provider, date, time, and location. A confirmation request (e.g., “Reply YES to confirm”) is also common.
• Abbreviations Useful: “Appt w/ Dr. Smith on May 17 @ 2PM at 123 Main St. Pls reply C to confirm or R to reschedule.”

Two-Factor Authentication (2FA) Codes / One-Time Passwords (OTPs)

These are almost always very short and to the point.

• Direct and Simple: “Your [YourBrand] verification code is: 123456. Do not share this code.”
• Character limits are rarely a concern for these types of messages.

How Web Creators Can Help Clients Navigate SMS Character Limits

As a web creator, you can provide significant value to your clients by helping them understand and effectively manage SMS character limits.

Educating Clients on Character Encoding and Concatenation

Many clients may not be aware of the technical reasons behind character limits or how easily a message can become multi-segment (and thus more costly).

• Clearly explain the difference between GSM-7 and UCS-2 encoding.
• Show them the impact of using emojis or special characters on the segment count (160 vs. 70 characters, then 153 vs. 67 for concatenated parts).
• Explain how concatenation works and the per-segment billing model.

Designing SMS-Friendly Content Strategies

Guide your clients in developing a mindset for SMS brevity.

• Advise them on how to write concise, impactful copy for their text messages.
• Encourage the use of mobile-optimized landing pages for more extensive information, using the SMS as a “gateway” with a clear link.
• Help them identify essential information versus “nice-to-have” details for SMS.

Choosing and Configuring SMS Tools with Clear Character Counting

When you’re setting up SMS capabilities for a client, especially within a WordPress site, the choice of tool matters.

• Recommend and implement SMS solutions that provide excellent real-time feedback to the user during message composition.
• For example, if a client is using WordPress and you integrate an SMS communication toolkit like Send by Elementor, a key aspect of your setup and training would be to highlight its message composition interface. You would show the client how Send by Elementor (ideally) features:
  • A dynamic character counter that updates as they type.
  • An SMS segment estimator (e.g., “1/2 segments used”).
  • An indicator that shows if the message is currently GSM-7 or has switched to UCS-2 due to a special character, and how that affects the per-segment limit.
• By ensuring the client understands how to use these features within their familiar WordPress dashboard, you empower them to make informed decisions about their message content, control their SMS costs, and optimize for clarity and user experience.

Training Clients on Best Practices for Brevity and Clarity

Provide practical training and resources.

• Share examples of good and bad SMS copy.
• Create a simple checklist or tip sheet for writing effective, short SMS messages.
• Emphasize the importance of testing messages on actual devices before sending campaigns.
• Show them how to use URL shorteners effectively (preferably branded ones).

Conclusion

The SMS character limit – typically 160 characters for GSM-7 encoding or 70 for UCS-2 – is a fundamental constraint of text messaging that every marketer and communicator needs to understand. It’s not just a technical footnote; it directly influences your campaign costs, user experience, and message clarity.

By grasping the nuances of character sets like GSM-7 and UCS-2, understanding how message concatenation works, and embracing best practices for writing concise and impactful copy, you can navigate these limits effectively. Using tools that provide real-time feedback on character counts and encoding within your messaging platform, especially if integrated into your website’s ecosystem like a WordPress solution, further empowers you to optimize every text. Mastering brevity within the SMS character limit isn’t about restriction; it’s about crafting more powerful, efficient, and cost-effective communication that truly resonates with your mobile audience.