# SMS character limits and credit usage guide

> Learn how message length and special characters affect SMS segments and credit usage in Caspen.

Source: https://support.caspen.com/settings/billing/sms-character-limits-and-credit-usage-guide
Documentation index: https://support.caspen.com/llms.txt

## Overview

Caspen uses standard SMS rules, which determine how long a message can be before it is split into segments. This is useful to know when writing appointment or class notifications, since longer messages can use more SMS credits.

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## How SMS segments work

#### Standard GSM characters
- 1 segment = **160** characters.
- Long messages use **153** characters per segment.

#### With emojis or special characters
- 1 segment = **70** characters.
- Long messages use **67** characters per segment.

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#### What counts as standard GSM
- Letters, numbers, spaces, and common punctuation (A–Z, a–z, 0–9, . , ! ? ' " : ; ( ) / @ #).

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#### Special characters
Special characters include:

- Curly quotes **“ ”** and **‘ ’**
- Long dashes
- Many accented letters (for example, **é** or **ü**)
- Symbols such as **{ } \[ ] ^ \ |**
- Emojis

Using emojis or special characters reduces how many characters fit in one SMS, which may increase the number of segments (and credits) used.

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## Cost
You use **1 SMS credit per outbound segment**.

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## Tips to reduce SMS costs
- Keep SMS short and clear.
- Use standard GSM characters.
- Limit emojis and special characters where possible, as they can increase cost.
- If you’re curious about credits, try an online SMS segment calculator to estimate usage.