SMS Segments Explained: Why One Text Can Cost 3x (Unicode, Emojis and Smart Quotes)

Key Takeaways:

• Text messaging is billed in segments, not messages. Your SMS credits, and the carrier surcharge on top of them, are charged per segment.
• One segment holds 160 characters in standard GSM-7 encoding, or only 70 characters if the message contains even one non-GSM character (Unicode).
• Once a message is split, each segment holds less: 153 characters (GSM-7) or 67 characters (Unicode).
• A single curly apostrophe pasted from Word or Outlook, a typographic dash or an emoji can switch the entire message to Unicode, turning a 1-segment text into 2 or 3.
• In 2026, carrier surcharges of roughly $0.0035 to $0.005 apply to every segment, so an unnoticed Unicode character multiplies both your credits and your carrier fees.
• TXTImpact's Unicode detection tool and the gateway's Replace Common Unicode Characters option help catch and fix these characters automatically.

If you have ever wondered why a text that looked like "one message" used three credits, the answer is the message segment. Segments are the currency of the texting world: every plan, credit balance and carrier invoice is ultimately counted in them. Understanding how they work is the easiest way to cut your cost per message without sending a single fewer text.

This guide explains what a segment is, how GSM-7 and Unicode change the math, how a simple copy-and-paste from Word or Outlook can silently triple your cost, and how to stop it.

What is an SMS segment?

An SMS is a tiny data packet. Under the original standard it can carry 140 bytes, which works out to:

• 160 characters if the text uses the 7-bit GSM alphabet (GSM-7), or
• 70 characters if the text needs the 16-bit Unicode (UCS-2) alphabet.

Anything longer is cut into several packets, called segments (or message parts), which the recipient's phone stitches back together so they read it as one message. To make that reassembly possible, each segment of a longer message gives up a few bytes to a header. That is why the per-segment limits shrink once a message is split:

So a 161-character GSM-7 message does not use "one message and a bit". It uses two segments, and a 71-character Unicode message does the same.

How segments become SMS credits

On TXTImpact, one text credit covers one outbound SMS segment to a US recipient, so the credit math follows the segment math directly. Here is how message length maps to credits:

Multiply by your audience and the stakes are clear. A 160-character message to 10,000 contacts uses 10,000 credits. If that same message contains one Unicode character, it becomes 3 segments and uses 30,000 credits. For the full credit rules, including MMS, RCS and surveys, see How do TXTImpact Text Credits Work?

The hidden trap: one character switches the whole message

The rule that catches almost everyone is this: encoding applies to the entire message, not just the odd character. A single emoji, curly quote or non-GSM symbol converts the whole body to Unicode, and the 160-character limit becomes 70 (or 67 per segment once split).

Here is a real-looking example. Both versions look identical on screen:

Hi Sam, don’t miss our Fall Sale – 20% off everything this weekend only! Show this text in-store. Reply STOP to opt out.

The first version has a curly apostrophe (’) and an en dash (–), the kind a word processor inserts automatically. It is 120 characters long, but because it is Unicode it needs 2 segments (120 divided by 67, rounded up). The second version uses a plain apostrophe (') and a plain hyphen (-). Same 120 characters, same look to the reader, but it fits in 1 segment. That is a 2x cost for nothing.

Where these characters sneak in

Most people never type a special character on purpose. They arrive through copy and paste:

• Microsoft Word and Outlook AutoCorrect. Typing a straight apostrophe or quote in Word or Outlook converts it to a curly "smart" character. Typing "--" becomes an em dash, and "..." becomes a single ellipsis character.
• Web pages and PDFs. Text copied from a site or document often carries non-breaking spaces, bullets, trademark symbols and typographic quotes that are invisible in the text box.
• Email signatures and templates. Autogenerated emails routed to text can carry decorative characters from the template.
• Spreadsheets and CRMs. Names with accents or imported product descriptions can introduce characters outside the GSM alphabet.

Which characters break GSM-7?

Here are the usual suspects, grouped by what happens:

The last row is a sneaky one. A 159-character message plus one euro sign is 161 GSM-7 characters, and needs 2 segments. TXTImpact's SMS characters limit page lists the full GSM 03.38 alphabet and extension set.

Emojis: fun, but they are priced as Unicode

Emojis are effective for engagement, but they come at a premium. Each emoji forces the entire message into Unicode, and most emojis occupy 2 of the 70 character positions (some occupy 4), as noted on our emoji text message page.

For example, take this 127-character GSM-7 message:

Hi Sam, our Fall Sale is on! 20% off everything this weekend only. Show this text in-store and save big. Reply STOP to opt out.

It fits in 1 segment. Add a single leaf emoji at the end and the message becomes Unicode and slightly longer (130 character positions), so it needs 2 segments. One tiny emoji just doubled the cost of every send.

That does not mean you should never use emojis. It means you should use them knowingly: budget for the extra segments, keep the message short enough to still fit in a single Unicode segment (70 characters), and test before you send.

Why it matters even more in 2026: carrier surcharges are per segment

Carriers do not bill you per message. They bill per segment. Public carrier schedules state that SMS surcharges are billed per segment, and in 2026 those surcharges have gone up at AT&T ($0.0035), T-Mobile ($0.0045), Verizon ($0.005) and others. We break down the timeline in our guide to 10DLC carrier surcharges in 2026.

Because the surcharge repeats for each segment, a Unicode surprise multiplies it. Take a 160-character message that accidentally contains one smart quote, sent to 10,000 recipients. It becomes 3 segments each:

That is roughly $470 to $500 more for a campaign that looks exactly the same to the reader. The per-credit rate here is illustrative, based on TXTImpact's published Business plan; check the pricing page for current rates, and confirm how carrier fees appear on your invoice.

How to keep your messages at one segment

1. Type, don't paste. Compose directly in the messaging platform's editor. If you draft in Word or Outlook, paste into a plain-text editor first to strip smart quotes and special characters.
2. Turn off AutoCorrect for drafts. Disable "smart quotes" and automatic dash and ellipsis replacement in your word processor if you often draft SMS copy there.
3. Check the counter before you send. TXTImpact's free SMS testing tool shows word count, character count and live segment math (GSM-7 vs Unicode) so you see the segment count before it is billed.
4. Use the Unicode detection tool. Available from the Tools menu in the dashboard, it finds the exact symbols that push a message into Unicode, so you can swap them for GSM characters. See the help article.
5. Shorten links. A long URL eats characters and can push you into a second segment. TXTImpact's built-in branded short links free up room.
6. Choose emojis on purpose. Use one where it earns its place, and keep the message under 70 characters or accept the multi-segment cost.
7. Consider MMS for long content. If your message is long, an MMS (2 credits) can be cheaper than 4 or more SMS segments. For email-to-text, TXTImpact automatically converts emails over 160 characters to MMS at 2 credits. Learn more about MMS messaging.

How TXTImpact helps: Replace Common Unicode Characters

You should not need to proofread every message for invisible characters, especially when messages come from automated systems, email, Outlook or API calls that you do not control. That is where the TXTImpact SMS gateway's Replace Common Unicode Characters option comes in.

When enabled, the gateway swaps common look-alike Unicode characters, such as curly quotes, typographic dashes and similar symbols, with their plain GSM equivalents before the message is sent. The reader sees essentially the same text, but the message stays GSM-7, so it keeps the 160-character limit and uses fewer segments and credits.

This is especially useful when:

• Staff paste copy from Word, Outlook or a web page into mass texting campaigns.
• Alerts and notifications come in through email-to-text or the SMS gateway API from systems that generate typographic characters.
• Teams send from Outlook and the email body carries AutoCorrect characters.

If you genuinely need Unicode, for example to message customers in Arabic, Chinese, Hindi or Russian, or to include emojis, you can turn the option off or leave Unicode support to do its job. The goal is to avoid paying the Unicode premium by accident, not to remove it when you want it.

Segment cheat sheet

Conclusion: Count the Segments, Keep the Savings

Every texting bill has a hidden ruler behind it, and it is not the one you see on screen. You see one message. The carrier sees segments: 160 characters of plain text, or just 70 the moment a curly quote, a pasted dash or a cheerful emoji sneaks in. That tiny shift is how a campaign that should cost about $240 turns into one that costs about $720, without a single word of the copy changing.

The good news is that none of this is mysterious, and almost all of it is fixable. Type in plain characters. Treat Word and Outlook as places to draft ideas, not to copy from. Spend your emojis the way you would spend a marketing budget: on purpose. Check the count before you press send, and let the gateway's Replace Common Unicode Characters option catch what your eyes cannot.

In 2026, when every segment carries both a platform credit and a carrier surcharge, the shortest message is not just the clearest one. It is often the cheapest. Write as if every character has a price tag, because now it does.

Want to see your own segment counts and costs? Start a free 15-day trial, compare plans, or book a demo.

Carrier fees and character-set behavior can vary by carrier and handset. This article is general information; confirm current figures with your provider.

Frequently Asked Questions

What is an SMS segment?

A segment is one packet of a text message. A single segment holds up to 160 GSM-7 characters or 70 Unicode characters. Longer messages are split into multiple segments of 153 (GSM-7) or 67 (Unicode) characters each, and the recipient's phone reassembles them.

Why did my text use more than one credit?

Either it is longer than 160 characters, or it contains a character outside the GSM-7 alphabet, such as a curly quote, an en dash, an emoji or a non-Latin letter, which switches the entire message to Unicode and cuts the limit to 70 characters.

Why does copying from Word or Outlook cause problems?

Word and Outlook automatically replace straight quotes, hyphens and three dots with typographic versions. These look the same but are not in the GSM-7 alphabet, so they convert your whole message to Unicode.

Do emojis cost more to send?

Yes. An emoji switches the message to Unicode, which allows only 70 characters per segment, and most emojis use 2 character positions. A message that fit in one segment can become two or three.

Do carrier surcharges apply to each segment?

Yes. Carrier SMS surcharges are billed per segment, so a 3-segment message carries three carrier fees as well as three platform credits.

How can I check how many segments my message uses?

Use the character and segment counter in TXTImpact's free SMS tools or the Unicode detection tool in your dashboard before sending.

What does the Replace Common Unicode Characters option do?

It automatically swaps common look-alike Unicode characters, such as curly quotes and typographic dashes, for plain GSM equivalents so your message stays GSM-7 and uses fewer segments.

A Final Word from TXTImpact

At TXTImpact, we have spent more than 20 years watching the messaging industry change. SMS is still one of the most powerful ways for businesses to engage customers, users and employees. At the same time, it comes with a cost. Knowing how it works, from message segments to carrier surcharges, is the best way to avoid surprise bills and set your texting program up for success.