Understanding SMS segments and costs
Why a long text counts as multiple messages, and how the composer helps you keep messages tidy.
A standard SMS holds 160 characters. Anything longer is split into multiple “segments” that each count, and bill, as a separate message.
This is a quirk of how SMS itself works, not a Rezi rule. The protocol, designed in the 1980s, carries 160 characters per message; everything since has been workarounds. Modern phones hide the seams by stitching segments back together on screen, so your guest sees one long message, but the network (and the billing) still counts each segment separately. Knowing the thresholds turns message length from a mystery into a choice.
| Message length | Segments | Notes |
|---|---|---|
| 1-160 characters | 1 | Standard single message |
| 161-306 characters | 2 | Split adds overhead, so the threshold drops to ~153/segment |
| Emoji or special characters | More | Some characters switch the message to a format that holds only 70 per segment |
The two gotchas worth knowing
First, the overhead drop: once a message exceeds 160 characters, every segment needs stitching information, shrinking usable space to about 153 characters each. So 161 characters costs two segments, the second one nearly empty, the worst value in texting. Second, the encoding switch: a single emoji, or certain typographic characters like curly quotes pasted from a word processor, flips the entire message to a different encoding that fits only 70 characters per segment. One stray character can more than double the segment count of a long message.
Why this matters mostly for broadcasts
For one-on-one conversation, segments are a rounding error, reply length is whatever the answer needs. The math gets real in broadcasts: a 2-segment message to a 150-recipient list is 300 segments instead of 150, and if an emoji flipped the encoding, it could be 600. The composer’s live counter exists exactly for this moment, glance at it before sending to a big audience.
Watch the counter
The broadcast composer shows a live character counter and warns you right before you cross a segment boundary. Trimming a few words can cut a 2-segment message back to 1.
Writing tight without sounding terse
Most notices fit one segment after honest editing: lead with the fact (“Water off Tue 9am-1pm, building-wide pipe repair”), cut the throat-clearing (“We wanted to let you know that…” costs 35 characters and says nothing), and let Rezi handle follow-up questions individually instead of pre-answering everything in the blast. If the content genuinely needs two segments, that’s fine, clarity beats compression, just make it a decision rather than an accident.
Do segments matter for the AI’s replies to guests?
Do guests see the message broken into pieces?
Are incoming messages from guests segmented too?
Should I avoid emoji entirely?
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