SMS Length Calculator — GSM-7 & Unicode Segments

This page opens the character counter in SMS mode: as you type, it detects the encoding your message will actually use, counts the segments carriers will bill, and shows how many characters remain in the current segment.

The honest math: if every character fits the GSM-7 alphabet (basic Latin letters, digits, common punctuation), one SMS carries 160 characters, and longer texts split into segments of 153 (7 characters go to the stitching headers). But a single character outside that alphabet — an emoji, a smart quote “like this”, or letters from most non-Latin scripts — silently switches the entire message to Unicode (UCS-2), where one SMS holds only 70 characters and split segments hold 67. One stray character can double or triple the cost of a campaign.

The calculator shows the detected encoding live, so you can spot the exact moment your text flips from GSM-7 to Unicode and decide whether that emoji is worth an extra segment. Everything is computed locally in your browser.