SMS Character Limit: How to Keep Every Text to One Segment

Quick answer: A single SMS holds 160 characters. Add one emoji or special character and the limit drops to 70. Go over it and the text is split into segments of 153 characters (or 67 with an emoji), and you pay for every segment. The phone still shows one message, so most brands never notice they're paying double. Our default: 1 message, 1 billable segment.

Most brands treat SMS length as a copy question.

It's a cost question.

Email makes us a bit lazy here. Sending one more email to 50,000 people costs next to nothing. SMS works more like paid media. Every recipient costs money, and every segment costs money.

So one fire emoji can double or triple the cost of a campaign without anyone on the team noticing.

Here's how the SMS character limit actually works, what eats into it in Klaviyo, and how we keep every text in one segment.

By Emiel Dingemans, Founder of Magicianly

Updated November 2026

What Is the SMS Character Limit?

The SMS character limit is 160 characters per segment when the message only uses the standard GSM-7 character set. If the text contains even one emoji or special character, the whole message switches to UCS-2 encoding and the limit drops to 70 characters.

That isn't a Klaviyo rule. It's how SMS works everywhere. A segment carries 140 bytes of data. Standard characters take 7 bits each, so 160 fit. Unicode characters take 16 bits each, so only 70 fit.

What Is an SMS Segment?

An SMS segment is the unit carriers deliver and platforms bill. When a text is longer than one segment, it's split into several, and the recipient's phone stitches them back together so it looks like one message.

To do that, every segment carries a small header with instructions for putting the message back together. That header takes up space. That's why a split message holds 153 characters per segment instead of 160, or 67 instead of 70.

So a 161-character text isn't "a little over". It's 2 segments: 153 characters in the first and 8 in the second. You pay for both.

Klaviyo lets you write up to 1,600 characters in one text. That doesn't mean you should.

How Many Characters Fit in 2 or 3 SMS Segments?

What Does an Extra SMS Segment Cost?

Every extra segment is another billable message. The cost of a send is simple:

Recipients x segments x your rate per segment

Say you text 50,000 subscribers and your rate is $0.01 per segment. That's just an easy number for the example. Your real rate depends on the country, the number type and your plan, and you can see it in Klaviyo under your billing settings.

Same audience. Same offer. Almost the same message on the phone. Three times the cost.

And that extra cost comes straight out of profit. That's why we never look at SMS revenue on its own. Say a campaign shows $800 in revenue and cost $500 to send. At a 60% contribution margin, that $800 is $480 of contribution. Take off the $500 and the campaign lost $20. And that's assuming every one of those orders was caused by the text.

Doubling your segment count is the fastest way to end up there.

Do Emojis Count Toward the SMS Character Limit?

Yes, and they cost a lot more than one character. One emoji switches the entire message to UCS-2, so the single-segment limit drops from 160 to 70. Many emojis also count as 2 characters on their own.

Here's what that looks like. Take the first example text further down this page, with a short brand name and a shortened link. It's about 150 characters including the opt-out text: 1 segment. Add one fire emoji at the start and it becomes 3 segments.

Our default is no emojis and no special characters. We only use one if the message still fits in 1 segment, or if there's a really strong reason. A fire emoji isn't worth doubling the cost of a send.

Agree on this with the brand upfront, too. Founders often want emojis, or longer and more natural sentences, without knowing what it does to the bill. For when an emoji does fit, see our SMS marketing examples.

Which Characters Trigger the 70-Character Limit?

Anything outside the GSM-7 character set. Emojis are the obvious ones. The sneaky ones look completely normal:

• Curly quotes and apostrophes pasted from Google Docs, Word or Notion. Klaviyo automatically swaps some lookalikes, like curly double quotes, for the standard version before sending, but not every one.
• Some accented letters. é, ñ and ü are fine. á, í, ó, ú and ç aren't.
• Symbols like © and ™.
• Lookalike letters copied from somewhere else, like a Cyrillic "а" that looks exactly like a normal "a".

A few standard characters don't switch the encoding but count as 2 characters each: [ ] { } | ~ ^ and the backslash.

The easiest fix is to type the copy directly in Klaviyo's SMS editor instead of pasting it, and watch the counter. If the count jumps for no clear reason, check Klaviyo's list of special characters.

What Else Counts Toward the Character Limit in Klaviyo?

Everything in the message counts, not just your copy. In Klaviyo that includes:

• Your company prefix. Your brand name at the start of the text. It's optional in some countries and required in others, and for UK numeric sending numbers Klaviyo adds it even if you turn it off.
• Opt-out text. On numbers that can receive replies, Klaviyo adds unsubscribe instructions. The default "Text STOP to opt-out" is 20 characters including the line break.
• Links. Klaviyo shortens links for click tracking, but the short link still takes up characters.
• Personalization. A first name tag is estimated at a fixed length in the preview, but "Alexandra" is longer than "Jordan". Klaviyo itself recommends staying under 155 characters to leave room for that.

So 160 characters is never really 160 characters of copy. That's why we don't count characters by hand. We check Klaviyo's segment count in the preview before every send.

Why Do UK Texts Hit the Limit Faster?

Because of the branded sender ID. A lot of UK brands send texts from their brand name instead of a phone number. A branded sender ID can't receive replies, so customers can't text STOP. Klaviyo automatically adds an unsubscribe link instead, and you can't turn it off.

That link is longer than "Text STOP to opt-out". So the exact same copy can fit in 1 segment in the US and need 2 in the UK. If one campaign goes to both countries, some recipients get the link and others get the instructions, so check the preview for both.

UK texts also cost a lot more per message to begin with. We regularly see UK rates of 3 to 6 times the US rate. So for UK brands we're extra strict: smaller audiences, fewer sends, 1 segment, and an honest look at whether the message needs to be an SMS at all.

How Do You Keep an SMS to One Segment?

This is the checklist we run before any text goes out:

1. 1Write in plain text. No emojis, no curly quotes, no special characters. Type it in Klaviyo instead of pasting from a doc.
2. 2One message, one job. What's happening, why it matters now, and the link. That's it.
3. 3Cut filler. "We're so excited to let you know that our biggest sale of the year has officially started" becomes "Black Friday is live".
4. 4Let the link do the work. We use links that apply the discount code automatically, so the text doesn't need to explain how to use a code.
5. 5Leave room for personalization, or skip the first name.
6. 6Check Klaviyo's segment counter in the preview before you schedule it. Not your own count.
7. 7Only go to 2 segments on purpose, when you're confident the extra cost will earn itself back.

The same rules apply to flows. A welcome or abandoned cart text sends every day, so an extra segment there doesn't cost you once. It costs you on every single send.

What Does a One-Segment SMS Look Like?

Three texts we'd send, each well within 1 segment with a short brand name, a shortened link and the opt-out text:

Sale launch:

[Brand Name]: Black Friday is live. 25% off everything until Monday, already applied at checkout. Shop now: [link] Text STOP to opt-out

Sale ends tonight:

[Brand Name]: Last call. 25% off ends tonight at midnight. Your code is already applied: [link] Text STOP to opt-out

Restock:

[Brand Name]: [Product Name] is back in stock. Grab yours before it sells out again: [link] Text STOP to opt-out

No emojis, no exclamation marks, nothing that needs explaining. Sale launches, last calls, launches and restocks are also the moments we think deserve a text in the first place. More on that in our SMS marketing best practices, and for the busiest week of the year, our Black Friday SMS marketing plan.

Is Basic RCS or MMS a Way Around the SMS Character Limit?

Partly. In the US, Klaviyo bills Basic RCS (text-only RCS) in 160-character segments too, so it isn't unlimited. But Klaviyo counts both text and emojis toward that 160, so an emoji doesn't cut the message to 70 the way it does in SMS. Outside the US, a text-only RCS message over 160 characters is billed as Single RCS, which costs more.

Two things to keep in mind:

• Every RCS message has an SMS fallback for phones and carriers that don't support RCS. That fallback follows normal SMS rules, so keep it to 1 segment as well. Klaviyo lets you edit the fallback separately.
• MMS allows up to 1,600 characters, but it usually costs a lot more per message than SMS. We only use it when we have evidence the image earns back the extra cost. Most of the time, it doesn't.

Our order: Basic RCS where it's available and priced close to SMS, SMS as the baseline everywhere else. For UK and European brands, WhatsApp is a different conversation, which we cover in Klaviyo WhatsApp vs SMS.

So What Is the SMS Character Limit?

• 160 characters for one SMS segment, 70 with any emoji or special character.
• Split messages hold 153 characters per segment, or 67 with an emoji, and every segment is billed.
• Send cost is recipients x segments x your rate, so an extra segment doubles the cost of the whole send.
• In Klaviyo, the prefix, opt-out text, links and personalization all count.
• UK branded sender IDs add an unsubscribe link, which can push the same copy into a second segment.
• Our default: plain text, one job per message, 1 billable segment, checked in Klaviyo's segment counter before every send.