FREE SMS Length Calculator

Short Message Service (SMS)

Short Message Service is a standard protocol that lets devices send and receive text messages. It was designed to use the spaces between other signals, which explains why messages are limited to 160 characters (using 7-bit encoding), or 140 bytes. SMS was first standardized in 1985 as part of GSM, and later built into the SMPP protocol that carries SMS messages.

What’s a Segment in a text message?

A single SMS message technically supports up to 160 characters, or up to 70 if the message contains one or more Unicode characters (such as emoji or Chinese characters).

If your messages exceed 160 characters, additional credits/SMS will be used or counted. Larger text messages are split into 153-character "segments" and sent individually, then re-assembled by the client's (recipient's) device.

SMS are billed for every message segment sent. If, for example, you send a message that is 140 characters long, you will be charged for one segment. If you send a message containing more than 160 characters to the same phone number, say 170 characters, your text message will now cost 2 segments.

Note: Keep messages under 320 characters for best deliverability.

Note: Some messaging platforms may only support messages up to 1600 characters.

SMS message length and character encoding

When SMS messages include non-GSM-7 characters (like Chinese script or emoji), they must use UCS-2 encoding. These messages can contain a maximum of 70 characters in a single, non-segmented message. If your UCS-2 message exceeds 70 characters, it will automatically split into multiple 67-character segments.

GSM-7 encoded messages

• 0-160 Characters: 1 segment
• 161-306 Characters: 2 segments
• 307-459 Characters: 3 segments

• And so on...

UCS-2 encoded messages

• 0-70 Characters: 1 segment
• 71-141 Characters: 2 segments
• 141-212 Characters: 3 segments

• And so on...

GSM-7 characters

A text message containing regular letters and numbers will be encoded using GSM-7.

GSM-7 example:

@ £ $ ¥ è é ù ì ò Ç Ø ø Å å Δ _ Φ Γ Λ Ω Π Ψ Σ Θ Ξ ESC Æ æ ß É ! " # ¤ % & ' ( ) * + , - . / 0 1 2 3 4 5 6 7 8 9 : ; < = > ? ¡ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Ä Ö Ñ Ü § ¿ a b c d e f g h i j k l m n o p q r s t u v w x y z ä ö ñ ü à

Unicode characters

A text message containing emojis or special characters like the Chinese script will be encoded using UCS-2 (known as Unicode characters). Even just one unicode character will change the encoding of your SMS.

Emojis can add personality to your SMS, but keep in mind they trigger Unicode encoding, reducing the limit to 70 characters per message.

Emoji unicode example:

😀 😁 😂 🤣 😃 👌

Non-emoji unicode example:

¢ ¦ ¨ © ª « ¬ ® ¯ ° ± ¹ ² ³ ´ µ ¶ · ¸ ¹ º » ¼ ½ ¾ À Á Â Ã È Ê Ë Ì Í Î Ï Ð Ò Ó Ô Õ × Ù Ú Û Ý Þ á â ã ç ê ë í î ï ð ó ô õ ÷ ú û ý þ ÿ

Basic best practices for SMS reminders and follow-ups

Sending too many messages too frequently can cause frustration and be seen as spam. For best results, consider the following:

• Make sure you have your client's consent to send them SMS and that they have opted in to receive them.
• Limit reminders to one per week. Use your Reminder Schedule to set up your reminders.
• If you need to send more reminders, stagger them over a few days.
• Keep messages concise, clear, and to the point.
• Adding your client’s name makes your message more personal, impactful, and likely to get a response.
• Send a test message to your phone to ensure your message is formatted correctly.
• Add a call-to-action (CTA) to your message to encourage a response.
• Read up on local and global SMS marketing laws and regulations.

Why SMS character count matters to your business?

The length of your message affects both cost and deliverability.

• Messages over 160 characters (or 70 characters if they include Unicode, like emojis) are split into multiple segments.
• Each segment is billed as a separate SMS.
• Longer messages can also increase the chance of transmission or formatting issues.

By keeping your SMS concise, you save money and ensure smoother delivery.

How do you avoid your SMS being split into multiple segments?

Here are some best practices for keeping SMS within a single segment:

• Stay under 160 characters (or 70 if using Unicode/emoji).
• Avoid special characters. Symbols and non-GSM characters can trigger Unicode encoding.
• Keep your SMS within the limit by using shorter words and reworking punctuation or sentence flow.
• Use ChatGPT or other AI tools to help you write shorter messages.
• Keep in mind that variables (like names or links) often expand in the final SMS, using more characters than expected.
• Use emojis sparingly.
• Keep your message simple and to the point.
• Use the SMS Length Calculator to check encoding and segmentation in real time.

Why should businesses use SMS for notifications and reminders?

Pairing SMS with email creates a multi-channel strategy to reach clients more effectively.

SMS notifications and reminders offer several key advantages for businesses. They provide a direct and immediate way to reach people, since most carry their phones at all times. Their concise, targeted format makes them ideal for delivering time-sensitive updates such as appointment reminders, service alerts, confirmations, or important notices. SMS also has very high open and read rates, which means your message is far more likely to be seen than through other channels. When used effectively, SMS notifications help improve reliability, reduce missed appointments, and strengthen trust by keeping customers informed in real time.

Why use this SMS length calculator tool?

This SMS length calculator tool is designed to help businesses and individuals calculate the length of their SMS messages. It is a useful tool for anyone who needs to send SMS messages, as it can help them ensure that their messages are within the character limit and avoid being split into multiple segments.

This tool is especially usefull for users looking to send SMS via Twilio (or other such SMS providers), Mailchimp, and OkaySend. It shows encoding type, character usage, and segmentation in real-time, so you can avoid costly text messages.