SMS Character Limit Checker

GSM-7 vs Unicode encoding

SMS messages send using one of two character encodings. GSM-7 is the original, more efficient encoding, packing each character into 7 bits and allowing up to 160 characters in a single message. If a message contains even one character outside the GSM-7 set, the entire message switches to Unicode (UCS-2) encoding, which uses 16 bits per character and cuts the single-message limit down to 70 characters. This is an all-or-nothing switch, one unsupported character forces the whole message to the lower limit.

How segmentation works

Once a message exceeds its single-message limit, carriers split it into multiple segments for delivery, each carrying a bit less text than the single-message limit to leave room for the metadata that lets a phone reassemble the pieces in order. GSM-7 multi-part segments hold 153 characters each, while Unicode multi-part segments hold 67 characters each. Most SMS platforms bill per segment, so a message needing 3 segments typically costs roughly three times a single-segment message.

Common characters that force Unicode without you noticing

Curly quotation marks and apostrophes pasted from a word processor, em dashes, most emoji, and many accented or non-Latin characters all fall outside the GSM-7 set. A message that looks short and simple can silently jump from a 160-character limit to a 70-character limit, and therefore from one segment to two or three, just because of a single curly apostrophe carried over from a copy and paste.

Want this done for you? Rankite offers monthly SEO management and SEO strategy session.