SMS & MMS Character Count Explained

Understanding how character counts work for SMS and MMS messages is essential for managing your text messaging campaigns effectively. Character limits determine how your messages are encoded, how many segments they're split into, and ultimately how they're billed. This article breaks down everything you need to know about character limits, encoding types, special characters, and best practices to help you get the most out of every send.

Table of Contents

• SMS Character Limits
• MMS Character Limits
• What Is Message Segmentation?
• Understanding GSM-7 vs. Unicode Encoding
• Special Characters and Common Pitfalls
• How Character Count Affects Billing
• Best Practices for Managing Character Count
• Character Count Quick-Reference Table
• FAQs

SMS Character Limits

SMS (Short Message Service) messages are text-only messages with character limits that depend on the type of encoding used:

• GSM-7 Encoding (Standard): Up to 160 characters per single message. This encoding covers standard English letters, numbers, and most common punctuation.
• Unicode (UCS-2) Encoding: Up to 70 characters per message. This encoding is automatically triggered when your message contains emojis, accented characters (e.g., ê, â, é), or other non-standard symbols.

Since Wunderkind's link shortener typically uses approximately 23 characters, we recommend keeping your body copy to:

• ~137 characters for standard GSM-7 messages
• ~47 characters for Unicode messages (those containing emojis or special characters)

💡 Tip: Required legal and opt-out language (e.g., "Reply STOP to unsubscribe") also counts toward your character limit and cannot be removed.

MMS Character Limits

MMS (Multimedia Messaging Service) messages include media such as images, GIFs, or videos alongside text. The text portion of an MMS has a significantly higher character limit:

• GSM-7 Encoding: Up to 1,600 characters when the entire message consists of standard GSM characters.
• Unicode (UCS-2) Encoding: The character limit is reduced when emojis or other non-GSM characters are used.

Because of the generous text limit, brands rarely hit the MMS character cap. However, keep in mind:

• Image file size matters. For optimal deliverability, keep image files under 200KB. The maximum upload size is 500KB — anything larger may be degraded by carriers.
• Supported MMS file types include JPG, PNG, and GIF.

What Is Message Segmentation?

When your message exceeds the character limit for its encoding type, it is automatically split into multiple segments. Here's how it works:

• A GSM-7 message over 160 characters is divided into segments of approximately 153 characters each (the remaining characters are used for concatenation headers that allow the segments to be reassembled).
• A Unicode message over 70 characters is divided into segments of approximately 67 characters each.

The good news: On modern smartphones, multi-segment messages still appear as a single, seamless message to the recipient.

The important part: Each segment is billed as a separate message. So a 162-character GSM message would be billed as two messages, not one.

Understanding GSM-7 vs. Unicode Encoding

Your message's encoding type is determined automatically based on the characters you use. Even a single non-GSM character will switch the entire message to Unicode encoding, which cuts your character limit significantly.

GSM-7 (Standard Encoding)

Supports the following characters at 160 characters per segment:

• Letters A–Z (upper and lowercase)
• Numbers 0–9
• Common punctuation: . , ! ? ' " - / ( ) : ; @ & + = % $ # * and space

GSM-7 Extended Characters (Count as 2 Characters)

Certain characters are part of the GSM-7 extended set and use two character slots each:

{ } [ ] \ ~ ^ | €

Unicode (UCS-2 Encoding)

Triggered when your message includes any of the following:

• Emojis (e.g., 🎉, 💡, 🛒)
• Accented or non-Latin characters (e.g., ê, â, é, ñ, ü)
• Special typographic characters (e.g., the single-character ellipsis …, smart quotes " ", em dashes —)

⚠️ Important: The encoding switch applies to the entire message, not just the character that triggered it. One emoji in a 150-character message means the whole message is encoded as Unicode and will be split into multiple segments (at 70 characters per segment).

Special Characters and Common Pitfalls

Some characters can unexpectedly increase your costs. Here are the most common pitfalls to watch for:

The Ellipsis Trap

The single-character ellipsis (…) is a Unicode character. If you use it, your entire message switches to Unicode encoding, potentially doubling your send cost. Replace it with three regular periods (...)to stay in GSM-7 encoding.

Emojis

Using even one emoji switches the message to Unicode, reducing your limit from 160 to 70 characters. While emojis can be engaging, testing has shown they have neither a positive nor negative impact on conversion rates or revenue, so consider whether the added cost is worth it for your campaign.

Compound Emojis

Some emojis are actually composed of multiple characters joined together (e.g., 🧑‍💻 or 👨‍👩‍👧‍👦). These compound emojis may count as more characters than expected and can behave unpredictably in character counters.

Copy-Pasted Text

Text copied from word processors (like Microsoft Word or Google Docs) may contain hidden Unicode characters such as smart quotes (“ ” instead of "), em dashes (— instead of -), or non-breaking spaces. Always compose your message directly in the campaign builder or double-check pasted text.

How Character Count Affects Billing

Understanding character count is directly tied to understanding your messaging costs.

SMS Billing

Each message segment counts as one billable SMS send. If your message exceeds the character limit, you are billed for each additional segment:

MMS Billing

MMS messages are billed differently. The image (or GIF/video) counts as one MMS send, and the accompanying text is billed as one or more SMS sends based on the same character count rules described above.

💡Tip: MMS sends cost more than SMS sends. If your campaign doesn't require an image, consider using SMS to reduce costs. A healthy mix of both SMS and MMS tends to drive the best engagement.

Best Practices for Managing Character Count

Follow these guidelines to keep your messages effective and cost-efficient:

• Aim for ~137 characters (GSM-7) or ~47 characters (Unicode) to leave room for the shortened link and any required legal language.
• Include your brand name in every message — this is a compliance requirement and helps recipients identify who the message is from, since texts are sent from a numeric short code.
• Use the message preview in the campaign builder to verify your character count and see how the message will appear before sending.
• Avoid unnecessary emojis if staying within the GSM-7 limit is important for your budget. If you do use emojis, keep your total copy to 47 characters or fewer.
• Replace Unicode look-alikes with GSM equivalents — for example, use three periods (...) instead of the ellipsis character (…), and use straight quotes instead of smart quotes.
• Use line breaks strategically to improve readability and make your link stand out. In the Wunderkind campaign builder, press Shift + Return to create a line break.

Character Count Quick-Reference Table

Note: When a message exceeds the single-segment limit, concatenation headers reduce usable characters to ~153 (GSM-7) or ~67 (Unicode) per segment.

Example: A 300-character GSM-7 message becomes 2 parts (153 + 147); a 150-character Unicode message becomes 3 parts (67 + 67 + 16).

FAQs

Why was my message billed as 2 (or more) sends?

Your message likely exceeded the character limit for its encoding type. For GSM-7 messages, the limit is 160 characters; for Unicode messages (containing emojis or special characters), the limit is 70 characters. Any message that goes over the limit is split into multiple segments, and each segment is billed separately.

Why did my character count drop to 70?

Your message contains at least one character that requires Unicode encoding — most commonly an emoji, an accented character, or a special typographic symbol like a smart quote or ellipsis. Even a single Unicode character switches the entire message to Unicode encoding, reducing the limit from 160 to 70.

Do links count toward the character limit?

Yes. Links are automatically shortened by the Wunderkind platform to approximately 23 characters, and this counts toward your total character limit.

Does opt-out and legal language count toward the character limit?

Yes. Required compliance language such as "Reply STOP to unsubscribe" counts toward your character limit and cannot be removed.

What's the difference between SMS and MMS pricing?

MMS messages cost more than SMS messages. When you send an MMS, you are billed for the media (image/GIF/video) as one MMS send, plus the text portion is billed as one or more SMS sends based on character count. For specific pricing details, please reach out to your Customer Success Manager.

Can I preview how my message will look before sending?

Yes. When building an On-Demand campaign in Connect, you can use the message preview to see your character count and how the message will appear on a mobile device. You can also send test messages to up to 10 phone numbers before finalizing your campaign.

For additional questions about character counts, billing, or text messaging best practices, please reach out to your Customer Success Manager.