SMS Character Counter

The 160-character limit comes from the GSM-7 encoding standard used by the original SMS protocol. Each GSM-7 character takes 7 bits, and a single SMS data block holds 140 bytes — which works out to exactly 160 characters (140 × 8 ÷ 7). It's an artifact of 1980s telecom engineering that's stuck around.

The moment you include an emoji (or any character outside GSM-7), the entire message switches to Unicode encoding. The limit per segment drops from 160 to 70 characters. So a 140-character message with no emoji sends as 1 SMS, but adding a single emoji pushes it to 2 or 3 segments depending on total length.

GSM-7 uses 7 bits per character and covers basic Latin text, digits, and common punctuation — giving you 160 characters per SMS. Unicode uses 16 bits per character and covers every language and emoji, but only fits 70 characters per SMS. Unicode messages cost more in bulk because they require more segments for the same length of text.

When an SMS spans multiple parts, each part includes a small header (called a UDH — User Data Header) that tells the receiving device how to reassemble them in order. That header consumes 7 bytes (GSM-7) or 6 bytes (Unicode) of each segment, leaving 153 or 67 characters for actual content.

The most effective thing is to remove emojis — that alone often drops you back to GSM-7 encoding and doubles your character budget. After that: shorten URLs with a URL shortener, avoid curly quotes (replace with straight ones), trim filler phrases, and check that no accented characters are slipping in.