How an SMS is counted

SMS is billed by the part. This is what a part is and why it is not simply the message length divided by 160.

The rule

A standard message is one part up to 160 characters. Past 160, the message is split, and each part carries 153 characters rather than 160 because the rest is used to tell the receiving phone how to reassemble them.

Messages containing characters outside the standard set are counted differently: 70 characters for one part, 67 per part after that.

The part everyone gets wrong

Ten characters cost two rather than one, even though they look like one on your screen. They are the square brackets, the curly braces, the backslash, the tilde, the pipe, the caret and the euro sign.

So a 158-character message full of curly braces is three parts, not one. If you counted characters and we billed parts, you would open a ticket about it, and you would be right to.

That is why the product counts parts the way the messaging standard counts them, rather than dividing by 160.

What proves it worked

The compose screen shows the part count before you send. Send it, then look at your usage. Same number.

Test it with a message just over 160 characters, and again with one containing a couple of curly braces. Both are the cases where an approximation and the real rule disagree.

Practical consequences

A signature costs parts. Twenty characters of name and agency on the end of a 150-character message makes it two parts, for every recipient, every time.

Links matter. A long tracking link can push a one-part message to two on its own.

Emoji are outside the standard set. One emoji anywhere in a message drops the whole message to the 70-character part size, not just the part it appears in.

Where the count appears

On the message before you send, on the usage view during the month, and on the invoice line at the end of it. All three come from the same number rather than from three calculations, so they cannot disagree.