TL;DR:

SMS character limits define the maximum payload size per text, ensuring proper routing, carrier compliance, clear messaging, and predictable delivery costs.

• Standard Cap: GSM-7 encoding allows 160 characters per SMS.
• Unicode Impact: Emojis and special symbols reduce limits to 70 characters.
• Segment Splitting: Multi-part messages cost extra due to underlying header data.
• Cost Efficiency: Concise copy prevents unintended segment costs and protects ROI.

 

Understanding how SMS character limits work can help you write messages that are clear, efficient, and less likely to be split into multiple segments.

Every mobile network globally relies on standardized character constraints, which dictate exactly how your copy gets processed and delivered. When a message exceeds these parameters, carriers automatically divide the text, potentially doubling or tripling your delivery costs without warning.

This guide covers the key factors that affect SMS length and how to make the most of the space available. By mastering message encoding and payload limits, you can protect your marketing ROI and deliver clean, high-impact messages every time.

SMS Character Count Explained

Every mobile network globally relies on standard protocols to handle message payloads. A single, standard SMS using standard character encoding has a hard limit of 160 characters. This default encoding is known as GSM-7 (Global System for Mobile Communications), which includes basic Latin letters, numbers, and a selection of common symbols.

Encoding Type	Standard Limit	Concatenated Segment
GSM-7	160 characters	153 characters / SMS
Unicode (UCS-2)	70 characters	67 characters / SMS

When you insert a non-standard character–such as an emoji, an accented letter, or non-Latin script–the entire message shifts from GSM-7 to Unicode (UCS-2) encoding. Because Unicode characters require more data per symbol, the single-message limit instantly drops from 160 down to 70 characters.

If your message exceeds the standard character limit, mobile carriers do not block it; instead, they split it into multiple text segments. However, these “concatenated messages” require extra routing headers (User Data Headers or UDH) to ensure the recipient’s handset seamlessly reassembles the text. These headers take up space, reducing the available payload per segment:

• GSM-7 Multi-part: Each segment is capped at 153 characters (rather than 160).
• Unicode Multi-part: Each segment is capped at 67 characters (rather than 70).

For example, a 170-character message in GSM-7 standard text won’t fit into one SMS. It gets split into two segments (153 characters + 17 characters), and you are billed for two separate messages.

Knowing your exact SMS character count ensures you avoid paying double for just a few extra characters.

Best Practices to Maximize SMS Character Count

Optimizing your messaging strategy requires balancing clear communication with structural efficiency. Even minor tweaks to formatting or phrasing can prevent unnecessary segment splits, lowering campaign costs while ensuring deliverability.

• Use GSM-7 characters whenever possible.
  Stick to the standard alphabet, standard numbers, and basic punctuation. Avoiding obscure symbols ensures your message stays at the 160-character baseline per segment.

• Avoid unnecessary emojis and special characters.
  Adding a single emoji converts the entire message payload to Unicode, instantly reducing your standard limit from 160 to 70 characters. If you must use emojis, ensure the high engagement rate justifies the extra segment costs.

• Keep messages concise and focused.
  Stick to a single clear value proposition and one specific call-to-action (CTA). Cut out extra adjectives or redundant details that do not add immediate value to the reader.

• Use abbreviations sparingly.
  While shortening words saves space, overusing “textspeak” or non-standard shorthand undermines brand authority and alienates readers. Stick to universally understood terms when necessary.

• Check text message characters before sending.
  Always run your draft through a character counter or SMS preview tool within your dashboard to detect hidden Unicode formatting or unexpected segment splits before broadcasting.

• Minimize unnecessary spaces and line breaks.
  Multi-line formatting adds extra hidden characters to your total count. Use single spaces and concise punctuation to separate ideas cleanly without inflating payload size.

• Plan longer messages to reduce the number of SMS segments.
  If a message exceeds 160 characters, target the 306-character mark (two GSM-7 segments) rather than spilling into a third segment by just three or four extra letters.

• Use Unicode only when necessary.
  Reserve Unicode for instances where specific non-Latin character sets (such as Cyrillic, Chinese, or Arabic) or critical brand elements are strictly required for communication.

By applying these structural refinements, you can consistently deliver high-impact copy while keeping campaign overheads fully optimized.

Take Control of Your SMS Deliverability and Costs

Mastering SMS character limits isn’t just about trimming unnecessary words—it’s about taking complete control over your marketing ROI, routing efficiency, and delivery success. A single stray emoji or hidden formatting error can silently multiply your messaging costs, transforming a straightforward broadcast into an expensive multi-part payload.

If you’re looking for a reliable, transparent partner to power your customer communications, consider Semaphore. Designed to bypass complex telecom contracts and cumbersome setups, our messaging platform offers continuous payload queueing, clear message logging, and instant API integration.

 

Explore Semaphore’s flexible SMS solutions today to keep your messaging scalable, compliant, and cost-efficient.

FAQ

 

• What is the character limit for a single SMS?

A single standard SMS contains up to 160 characters using GSM-7 encoding. If your message contains non-standard symbols or emojis, the single-message limit drops to 70 characters due to Unicode encoding. 

 

• What is the difference between GSM-7 and Unicode SMS?

GSM-7 uses standard 7-bit encoding designed for basic Latin letters, numbers, and common punctuation. Unicode (UCS-2) uses 16-bit encoding to support non-Latin scripts, accented letters, and modern emojis, taking up significantly more data per character. 

 

• Why do emojis affect SMS character limits?

Emojis are complex 16-bit symbols that force mobile carriers to switch the entire message payload from GSM-7 to Unicode encoding. This encoding shift instantly reduces your available payload from 160 down to 70 characters per text. 

 

• Which characters can reduce the SMS character limit?

Emojis, non-Latin alphabets, and special accented characters drop your text cap to 70 characters. Additionally, extended GSM-7 symbols like brackets [ ], braces { }, or the euro sign € count as two characters each. 

 

• How are longer SMS messages split into segments?

Messages exceeding single-text limits are split into multi-part segments using User Data Headers (UDH) so recipient devices can reassemble them correctly. These extra header data lower the payload to 153 characters for GSM-7 and 67 characters for Unicode per segment.