Two separate things affect your message length: whether a character is in the GSM character set, and whether it is an extended character that occupies two slots.
Characters that switch the message to Unicode #
Anything outside the standard GSM character set, including:
- Indian language text — Hindi, Marathi, Tamil, Telugu, Bengali and so on
- Emoji and symbols such as ✓, ★, →
- Curly quotes and dashes — ‘ ‘ ” ” – — which Word, Google Docs and Excel insert automatically in place of plain ones
- Accented letters not in the GSM set
- Rupee and other currency symbols apart from a few the GSM set includes
One such character makes the entire message Unicode, cutting the limit from 160 to 70.
Characters that count as two #
These are in the GSM set, so they don’t force Unicode, but each takes two character slots:
[ ] \ ^ { } | ~ € and every line break.
A message with five line breaks has already spent ten characters on formatting.
Seeing exactly what you have #
Open Extra > SMS Length Calculator and paste your message. The Detailed View of SMS Build-up shows every character as a coloured square: green for a normal GSM character, red for one that needs Unicode. The red squares are the ones to replace. The page also lists the full GSM character set for reference.
The quickest fix for accidental Unicode #
Retype quotes, apostrophes and dashes directly in the panel rather than pasting them, or paste into a plain-text editor first. The send box replaces curly quotes with plain ones automatically, but other pasted characters pass through untouched.