SMS pricing has a dirty little unit problem: you're not billed per message, you're billed per segment — and one emoji can triple what a campaign costs without anyone noticing. Since our plans include 5,000 texts a month, we owe you the exact math of what that covers. Here it is, no hand-waving.
Segments in ninety seconds
- Text encoded in GSM-7 (plain letters, digits, most common punctuation) fits 160 characters in one segment.
- Go over 160 and the message is split into concatenated segments of 153 characters each (7 characters go to the glue headers). 161 characters = 2 segments.
- Include any character outside GSM-7 — an emoji, curly “smart quotes” pasted from a doc, an em-dash from a word processor — and the entire message re-encodes as UCS-2: 70 characters per segment (67 each when concatenated).
So: a 150-character promo is 1 segment. The same promo with a 💪 at the end is 3 segments. Same send, triple the cost. (A couple of characters are also “extended GSM” and count double — ~ ^ { } [ ] \ | and the euro sign — a niche trap, but a trap.)
Worked examples
| Message | Encoding | Segments |
|---|---|---|
| 145-char win-back, plain text | GSM-7 | 1 |
| Same message + one emoji (146 chars) | UCS-2 | 3 |
| 240-char announcement, plain text | GSM-7 | 2 |
| 240-char announcement with emoji | UCS-2 | 4 |
What 5,000 segments covers for a real store
Take a store with 1,800 opted-in members, running the lifecycle playbook, all messages kept to one segment:
- Monthly full-list announcement: 1,800
- Lapsing win-backs (say 300 members drift per month): 300
- New-member welcomes (150 signups): 150
- Tier/milestone notes (250): 250
- Two category campaigns (400 each): 800
Total: ~3,300 segments — comfortably inside 5,000, with room for a flash promo. The same program with emoji in every message runs ~9,900 segments: nearly double the included pool, with the difference billed at 2¢ per segment. One character class, triple the send volume. A 4,000-member list doing two full-list sends monthly will exceed 5,000 included no matter what — the extra ~3,000 segments bill at 2¢ each (about $60), which is fine if you know it's coming. The point isn't “never exceed”; it's “never be surprised.”
Operator rules we actually follow
- One segment is the discipline, not a limit. A win-back doesn't need 300 characters. “Hey Dana — your 340 pts = $10 off a restock this week. Reply STOP to opt out.” is 82.
- Emoji only when worth 3x. Occasionally it is — a tier-up celebration, say. Decide on purpose, not by paste.
- Watch for smuggled characters. Copy from a doc and you'll import curly quotes that flip encoding. (Our composer shows the live segment count and estimated cost before you hit send, precisely because this is invisible otherwise.)
- Count the compliance tail. “Reply STOP to opt out” is ~24 characters of every campaign message. Budget copy around it — it's non-negotiable for deliverability and law.
- Segment the audience, not just the message. Four targeted sends beat one blast on cost and conversion; blasting is how included pools evaporate.
Run your own numbers: (list size × full-list sends) + (targeted campaign sizes) × (segments per message). If a vendor quotes “unlimited texts,” ask what happens to throughput when everyone's unlimited — carriers are the ones who answer.
Sizing table: where does your store land?
Assuming the segmented cadence above (not monthly full-list blasts) and one-segment discipline:
| Opted-in list | Typical monthly segments | vs 5,000 included |
|---|---|---|
| 800 members | ~1,600 | Well inside; room for experiments |
| 1,800 members | ~3,300 | Inside, with headroom for one flash promo |
| 3,000 members | ~5,200 | Right at the line — trivial overage (2¢/segment) |
| 5,000 members | ~8,500 | steady overage at 2¢/segment — budget it, or trim full-list sends |
Quick answers
Do inbound texts count? Replies from customers (including STOP) are inbound; billing conventions vary by platform — ours meters outbound campaign segments, which is where the volume lives anyway. Do reminder/transactional texts count against the pool? Yes, everything outbound is a segment; the good news is transactional messages are short and personal, so they're one segment and they never waste. Why not just buy an “unlimited” plan? Because carriers aren't unlimited: your registered throughput and your sender reputation are the true ceiling, and platforms selling unlimited volume tend to be the ones blasting their way into filters. Metered pricing keeps the incentives honest — ours included. What's the single best cost lever? Message length discipline, then audience discipline. A store that writes 82-character win-backs to 300 lapsing members will out-earn one that sends 3-segment emoji novellas to 3,000 people, and it will spend a tenth as much doing it.
One last habit worth building: reconcile the bill against the plan once a quarter. Export the month's campaign log, multiply audiences by segments per message, and compare against what you were charged. It takes ten minutes, it catches encoding drift (someone pasted smart quotes into a template in March and nobody noticed), and it keeps the texting budget a number you decided rather than a number that happened to you.