SMS for Shopify in 2026 is a real channel — not a 2018-era novelty. The average revenue-per-subscriber on a well-run SMS list ranges $2-$8/month, compared to $0.80-$1.20 on email. The catch: SMS is a per-message channel with regulatory teeth, so getting the tool choice wrong costs more than getting email wrong.
This guide is the decision tree we use when a Shopify store asks “which SMS platform should we ship with”. Real numbers from running SMS programs across three different stores at 1k, 8k, and 25k subscribers.
1. The choice in one sentence
If SMS is a primary channel with dedicated growth strategy → Postscript. If SMS is a secondary upsell on top of email → Omnisend bundled or Klaviyo SMS add-on.
That’s the choice in one sentence. The rest of this guide is the math behind it.
2. The volume math
SMS pricing is per-segment (a 160-character chunk for plain SMS, 70 for MMS or non-GSM characters). Compare cost at three volume tiers on a US-only Shopify store:
| Subscribers | Monthly segments | Postscript | Klaviyo+SMS | Omnisend bundled |
|---|---|---|---|---|
| 1,000 | ~3,000 | $99/mo (Starter) | $50/mo SMS + $35 Klaviyo email = $85 | $25/mo Standard (covers SMS) |
| 8,000 | ~22,000 | $299/mo (Growth) | $200/mo SMS + $135 Klaviyo = $335 | $79/mo Pro |
| 25,000 | ~75,000 | $599/mo (Growth+) | $570/mo SMS + $260 Klaviyo = $830 | $230/mo Pro+ |
At every volume tier, Omnisend’s bundled SMS is the cheapest sticker price. Postscript is competitive at 8k+ subscribers when you account for capability (opt-in widgets, two-way inbox, AI features). Klaviyo’s SMS add-on is the most expensive across the board — only worth it if you’re already on Klaviyo for the segmentation depth.
The catch with the cheap option: Omnisend’s bundled SMS is functionally adequate, not best-in-class. Reply-handling is one-way oriented; subscriber acquisition tools are basic vs. Postscript’s purpose-built widgets. If SMS is a real channel for you, the cheap option has hidden costs in lost growth and lost conversation depth.
3. Subscriber acquisition: the hidden differentiator
The reason Postscript costs more is that it ships better tools for collecting subscribers. This is where most SMS platform comparisons skip the most important variable.
Postscript-specific acquisition tools:
- Two-tap consent widget (TCPA-compliant by default, optimized conversion rate)
- Scroll-triggered and exit-intent popups
- PDP-embedded inline opt-in forms
- Keyword opt-ins via SMS short codes
- Reply-keyword opt-in confirmations
- Tap-to-text widget for mobile
- Checkbox at checkout with regulatory text auto-inserted
Omnisend bundled tools:
- Checkbox at checkout
- Inline form embed (one style)
- Popup form (shared with email)
Klaviyo SMS add-on:
- Email-form-with-SMS-secondary widget (decent)
- Popup with phone field (good)
- Checkbox at checkout
If your acquisition strategy is “checkbox at checkout, occasional popup” — the bundle covers it. If your acquisition strategy involves dedicated growth campaigns, social-media-driven opt-ins, or campaign-specific widget targeting — Postscript pays back.
4. Compliance: the boring part that can ruin your day
US SMS has real legal teeth: TCPA carries $500-$1,500 per violation, class-action lawsuits are common. Don’t take shortcuts.
Mandatory:
- 10DLC carrier registration for any US-based store. Takes 3-7 business days. Postscript automates registration; Klaviyo and Omnisend mostly do too, but verify before your first send.
- Double opt-in for marketing SMS. Customer texts back to confirm before they’re on the list. Postscript enforces this by default; Klaviyo and Omnisend require you to configure it correctly.
- STOP / HELP keyword auto-handling per CTIA spec. All three tools handle this.
- Quiet hours (default 8am-9pm local time). All three tools support this; default settings vary.
- Audit log retained 7 years minimum. All three retain.
The most common failure mode we see across stores: configuring single opt-in instead of double (faster list growth, lower legal protection). Don’t. If a TCPA suit lands, the difference between “we confirmed via double opt-in” and “we assumed they opted in via checkbox” is the difference between dismissal and settlement.
- Postscript handles all five compliance items correctly by default — no thinking required
- Klaviyo / Omnisend handle 10DLC and quiet hours by default; double opt-in needs verification
- All three tools survive TCPA audits when configured correctly
- Mis-configured opt-in flow on any tool is a real legal exposure
- International compliance (GDPR, UK PECR) varies by tool — verify before sending outside US/CA
- 10DLC trust score affects deliverability; bad registration choices linger for months
5. The decision tree
Plot your store on three axes:
- Is SMS a primary channel? = weekly campaigns + dedicated list growth + two-way replies treated as conversations.
- Annual segment volume? = subscribers × messages per subscriber × 12 months.
- What email platform are you already on? = Klaviyo, Omnisend, Mailchimp, or none.
Apply this tree:
- Primary channel + 50k+ segments/year + any email: Postscript
- Primary channel + under 50k segments/year + any email: Klaviyo SMS add-on (if you’re on Klaviyo) or Postscript Starter (otherwise)
- Secondary channel + already on Omnisend: Omnisend bundled
- Secondary channel + already on Klaviyo: Klaviyo SMS add-on
- Secondary channel + already on Mailchimp: Switch to Omnisend (Mailchimp SMS is US/CA only and shallow)
90% of stores fit one of those branches.
6. The migration cost (don’t pick wrong)
Switching SMS platforms after launch is painful. Specifically:
- 10DLC re-registration: 3-7 business days, during which you can’t send. Time-sensitive launches get hurt.
- Subscriber re-consent risk: If you migrate without doing it correctly, you might lose 30-50% of your list to the new tool not recognizing them as opted-in. We’ve seen this go wrong.
- Flow re-build: Cart-abandonment SMS automations don’t port cleanly between tools. Plan a full re-build.
- Historical analytics gap: New tool starts with zero analytics history.
Plan to stay on whichever tool you pick for 18 months minimum. Pick for where you’ll be at 12-18 months, not where you are today.
7. Concrete picks by store profile
For the impatient:
- New Shopify store, under 500 SMS-eligible subscribers: Omnisend free tier with bundled SMS. Wait until 1,500-2,000 subscribers before reconsidering.
- $10k-30k MRR with growing SMS list, already on Omnisend: Omnisend Pro with bundled SMS. Saves ~$200/mo vs. moving to Postscript.
- $30k-100k MRR with SMS as a real strategy: Postscript Growth. The acquisition and AI features pay back.
- $100k+ MRR with established SMS program: Postscript Scale tier OR Klaviyo SMS at Klaviyo Plus pricing. Negotiate.
- B2B-ish Shopify or international-heavy: Klaviyo SMS add-on — best multi-country compliance handling.
For deep tool-level detail, our reviews:
8. What this looks like at the 12-month mark
If you ship SMS correctly:
- Subscriber list growing 3-5% per month from PDP / popup traffic
- Annual revenue from SMS hits $2-$5 per subscriber per month at steady state
- Send cost stays under 8% of attributed revenue
- Reply rate on conversational SMS sits at 10-15% (a real two-way channel)
If after 12 months your numbers are below these benchmarks, the issue is usually opt-in strategy, not the tool. Buy the audit before you buy the migration.
Postscript
SMS marketing specialist — built exclusively for Shopify.
from $100/mo
Last updated: May 2026.