# SMS essentials

How long an SMS can be, how accents and emojis change that, and why a single message can count as more than one SMS.

**Language:** en
**Audience:** platform
**TLDR:** Standard SMS use GSM-7 encoding for up to 160 characters; any accent, emoji, or non-Latin character switches to Unicode and drops the limit to 70 (67 once split), and each extra part is billed as its own SMS. Whether carriers keep your alphanumeric sender abroad or replace it with a number is set by per-country regulation, so use the sender's brand prefix to stay visible where it's swapped.
**Translation key:** platform.channels.sms.sms-essentials
**Search keywords:** sms length, how many characters in an sms, 160 characters, 70 characters, unicode sms, accents emojis sms, gsm-7, ucs-2, sms parts, sms counter, multipart sms, why is my sms two messages, remove unicode characters
**Related pages:** /platform/es/channels/sms/sms-essentials, /platform/en/channels/sms/senders-registration, /platform/en/channels/countries
**Docs index (every page):** https://docs.instasent.com/llms.txt
**This zone's index:** https://docs.instasent.com/platform/en/llms.txt
**This page:** https://docs.instasent.com/platform/en/channels/sms/sms-essentials/ (HTML) · https://docs.instasent.com/platform/en/channels/sms/sms-essentials.md (Markdown)
**Other language (es):** https://docs.instasent.com/platform/es/channels/sms/sms-essentials.md

An SMS looks simple, but two rules decide how long it can be and how many SMS a
single send really costs: how many characters fit in one message, and what happens
when you go over. Knowing them is what keeps your messages short, on-brand and easy
to budget. In short: stick to the basic character set and each message counts as a
single SMS.

## Length and encoding

A standard SMS holds up to **160 characters**. That "standard" is the GSM-7
character set: the Latin letters **A–Z** and **a–z**, the digits **0–9** and common
punctuation — what you type most of the time.

The moment you add a character outside that set — an accent (á, ñ), an emoji, or a
non-Latin alphabet — the message switches to **Unicode** encoding and the limit
drops straight to **70 characters**.

| Encoding         | When it's used                            | Characters per SMS                             |
| ---------------- | ----------------------------------------- | ---------------------------------------------- |
| Standard (GSM-7) | Latin letters, digits, common punctuation | 160                                            |
| Unicode          | Accents, emojis, non-Latin scripts        | 70 (67 per part when split across several SMS) |

## When a message counts as more than one SMS

If your text goes over the limit, it isn't cut off: it's split into several SMS and
sent together, so your contact still reads it as **one message**. The difference
shows up on the bill, because each part counts as **one SMS**: a 200-character
standard message is two SMS,
and a message that tips into Unicode (say, one emoji) can become two as well.
With Unicode the per-SMS limit also tightens when the message splits: a single
Unicode SMS holds **70** characters, but **67 per part** once it spans more than
one SMS, because each part carries the data needed to reassemble them. Knowing
this lets you keep most messages to a single SMS and your costs predictable.

> **Tip**: Watch the **SMS** counter next to the message box while you write. It tells you
> how many SMS each contact will receive before you send.

![The SMS counter and Unicode warning in the campaign editor](/platform/en/channels/images/sms-essentials-1.png)
*The SMS counter and the Unicode warning in the message editor.*

## Avoiding accidental Unicode

Sometimes a single accent or emoji is enough to halve your limit without you
noticing. When that happens, the editor flags it with a banner — **This message
contains unicode characters** — explaining that Unicode caps each SMS at 70
characters instead of 160.

If the Unicode wasn't intentional, use **Remove unicode characters** to swap them
for their plain equivalents automatically (Á → A, ó → o). Your message goes back
to the 160-character standard limit.

## How your sender appears abroad

In some countries carriers replace an alphanumeric sender with a number before
delivering the message. When that happens your contact sees a number instead of your
brand name, and can't tell the SMS is from you. The usual fix is to name your brand
in the **message text** — in international campaigns you sometimes need to and
sometimes don't, depending on the destination.

To handle this without editing every message, set a **Brand prefix** on the
sender. It's a short text Instasent prepends to the message automatically, and
**only in the countries that replace the alphanumeric sender** — so your brand
stays visible there without showing twice where the sender already carries it.
It's a field on the sender itself, configured once in the sender's settings, not
something you add to the body each time.

Which countries replace the sender is a regulatory matter, covered in
[Countries & regulation](/platform/en/channels/countries); senders (and the brand
prefix field) are managed in
[SMS senders & registration](/platform/en/channels/sms/senders-registration).

## Messages in several languages

A campaign can carry several language versions of the same SMS; each contact gets
the version that matches their language, and everyone else gets the default. You
set this up while writing the campaign — see
[Creating a campaign](/platform/en/campaigns/creating-a-campaign).

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This is one page of the Instasent documentation. For the complete machine-readable index of every guide and API reference, fetch https://docs.instasent.com/llms.txt — start there for full context.