A text message has a size limit. When your message is longer than that limit, the carriers break it into pieces called segments. Each segment is billed separately. This article explains what counts as a segment, why the count goes up, and what you can do to keep it low.
Where to see the segment count
When you build an SMS campaign, type your message into the message box. As soon as there is text in the box, a few details appear right below it:
A badge showing the message type, either SMS or MMS.
A short explanation line.
A characters count.
The full breakdown shows in the Estimated cost panel, which lists:
Message type (SMS or MMS)
Price per message (per SMS or per MMS)
Characters length
SMS segments
Current audience (how many people)
Total cost
The SMS segments number is what gets multiplied across your audience to estimate cost.
How segments are counted
The segment count depends on how long your message is and which characters you use.
If your message uses only standard text characters (letters, numbers, and common punctuation):
A message of 160 characters or fewer is 1 segment.
A longer message is split into segments of 153 characters each.
If your message includes a special character such as an emoji or certain accented or symbol characters, the whole message switches to a different encoding, and the limits drop:
A message of 70 characters or fewer is 1 segment.
A longer message is split into segments of 67 characters each.
So a single emoji can move your message from 1 segment to 2 or more, even if the text looks short.
Why a short message can still be more than one segment
A few things commonly push the count up:
Emojis and special characters. One emoji switches the whole message to the lower 70 and 67 character limits. The estimate panel shows a warning: "Warning: you have a special character like an emoji, remove it for lower cost."
Some symbols count as two characters. Characters like
^,{,},\,[,~,],|, and€each take up the space of two characters even in a standard message.Merge fields. If you use Merge Fields to insert a person's name or other details, the real length depends on the value that gets filled in for each recipient. A long first name or address can make a message longer than it looks while you are typing.
Line breaks count too. Every line break is a character.
When the message switches to MMS
The campaign builder will automatically switch your message to MMS in two cases:
You attach an image or video. MMS is required to send media.
Your text is long enough that sending it as multiple SMS segments would cost more than one MMS. This happens at 3 or more segments, because three SMS segments cost more than a single MMS.
When this happens for cost reasons, the message type shows "(auto-switched for cost savings)" and the panel shows a line like "Saves $0.01 by using MMS instead of 3 SMS segments." You do not need to do anything. The builder picks the cheaper option for you.
How to reduce segments
Shorten the message. Aim to keep standard-text messages at or under 160 characters to stay at 1 segment.
Remove emojis and special characters. Replacing an emoji with plain text can drop you back to the higher 160 character limit.
Watch the characters count. It updates live below the message box as you type.
Account for merge fields. Remember that inserted values can be longer than the placeholder. Leave some room.
Avoid symbol-heavy text. Symbols like
{,},[,],~, and|each use double the space.
The maximum message length
A single text message can be up to 1,600 characters. If you go over that, you will see a red warning: "Message exceeds the 1600 character limit. Please shorten your message." You will need to shorten the message before you can send it.