SMS and MMS Character Limits Per Segment

Here is a guide to understand the math behind the calculations shown on the message composer


  Max Character Length Per Segment
Text message 160 characters
Text message with emoji 70 characters
Text message with image 1600 characters
Text message with image and emoji 1000 characters


The numerator in our calculations = company short name + characters you type in the message composer + URL


There are 192 characters in this message. Here is how we calculated it:

  • Company short name = MercerMain:
    • 12 characters with the space at the end
  • Characters you type in the message composer = Great! If you are most interested in receiving discounts and news from Celebs: reply 1, Athletes, reply: 2, Musicians, reply: 3, YouTubers, reply: 4
    • 149 characters with the space at the end
  • URL:
    • 31 characters

Since this is a text message with no image or emojis, 160 characters is the limit per segment. Thus this message would cost 2 segments 

When using dynamic variables (example: ), keep in mind that we can't guarantee specific character counts. The actual number of segments you will be billed for will be greater than or less than the preview number displayed

What is the History Behind SMS Message Length?

SMS is a standardized communication protocol that enables devices to exchange short text messages and was defined as part of the 1985 GSM protocol. Voyage doesn't control these rules. Originally it was designed to "fit in between" existing signaling protocols which is why SMS length is limited to 160 seven-bit characters. It was subsequently codified into the SMPP signalling protocol that transmits SMS and is limited to precisely 140 bytes (or 1120 bits).