Adding personalisation markers that contain data fields or Liquid markup to your SMS messages is a great way to communicate directly with your customers – in fact, due to the personal nature of SMS, most users expect a higher level of personalisation.

But before using your personalisation markers, it's essential to be aware of how personalisation can increase the overall message length and cost of your SMS sends.

One SMS message segment has a maximum character count of 160 characters. Every time the character count of the SMS message is more than 160 characters, it is sent and charged as two SMS message segments – these segments are combined and appear as one message on your customer’s phone, but they are still billed individually.

You've written a 155-character SMS message to send to your contacts. You've started the message with some personalisation by adding the FIRSTNAME data field. On the message preview; it looks like this:

Hey, @FIRSTNAME@.

At this point, we can't give you an accurate character count for your message, because the character count is different for every contact depending on the length of their first name.

To keep things simple, imagine you only have two contacts in your list: Amar and Charlotte. Because Charlotte has over double the number of characters in her name, the SMS message to her has more characters. The breakdown below demonstrates how the character count, message count, and overall billing cost is affected by the personalisation added to these two SMS messages.

Don't avoid using personalisation, but be aware of the possible additional cost when adding personalisation markers.

If you do use personalisation, try to keep messages short and know the maximum length of the data fields or Liquid markup you're adding. If you can't keep it short, be happy that although it may cost more, adding the personal touch can make your message more effective.