Marketing Mythbusters: The Great SMS Length Debate — 160 vs. 320 Characters

Introduction: Why SMS Length Still Sparks Debate

The debate over SMS message length—160 characters vs. 320—has divided marketers for years. Should you stick to the classic one-part SMS for optimal delivery and cost? Or double the space to tell a better story?

As SMS marketing becomes more sophisticated, the real question isn’t just about length—it’s about effectiveness. In this post, we’ll break down the science, psychology, and data behind SMS length and guide you toward smarter campaign choices.

Part 1: The History Behind 160 Characters

SMS started in the 1980s with a 160-character limit. It wasn’t arbitrary:

• 160 was chosen based on research into typical sentence length.

• Networks were optimized to handle these compact messages.

This limit became the industry standard, baked into early devices and billing systems.

Even today, most carriers segment longer messages into multiple parts, each potentially counting as a separate message.

Part 2: Why 160 Characters Still Matters

1. Lower Cost Most SMS providers bill per 160-character segment. A 161-character message may cost double.

2. Simplicity Works Short messages force clarity. One sharp CTA usually converts better than a paragraph.

3. Compatibility and Reliability Older phones or certain international routes may split longer messages awkwardly.

Part 3: The Case for 320 (and Beyond)

While 160 is standard, modern SMS tools support longer messages, and that opens up creative options:

1. Storytelling: Two-part messages allow for context plus a call to action.

2. Emotional Resonance: More space lets you create urgency, excitement, or connection.

3. Branded Experience: Longer messages can include dynamic variables, product descriptions, and landing page teasers.

Example:

• 160: "Get 25% off today only! Use code SPRING at checkout."

• 320: "Flash Sale! 🌟 Get 25% off all items until midnight. Use code SPRING at checkout. Don’t miss your chance to save—shop now at our site."

Part 4: Deliverability & Carrier Behavior

A common myth: longer messages are more likely to be flagged or blocked.

Truth: Message length alone doesn’t hurt deliverability—content quality does.

What matters more:

• Spammy words (FREE!!!, CLICK NOW)

• Use of shortened links

• Sender reputation

That said, some SMS gateways handle multipart messages differently, which may introduce delays or display issues.

Part 5: What the Data Says

Split testing reveals:

• Messages under 160 get a slightly higher delivery rate—but only by ~2–3%.

• 320-character messages see a 12–18% increase in engagement when crafted well.

• Bounce rates and opt-outs are more related to frequency and relevance, not message length.

Part 6: When to Go Short vs. Long

Use 160 when:

• Sending alerts, reminders, or 1-step actions

• Optimizing for cost

• Campaigns rely on speed and simplicity

Use 320 when:

• Promoting a special event or multi-step offer

• You need emotional appeal or brand voice

• Telling a story or giving context matters

Part 7: The Smart Way Forward — Test and Track

There’s no one-size-fits-all. The smartest SMS marketers:

• A/B test message length

• Monitor deliverability across segments

• Track conversions by message version

• Combine SMS with other channels (email, push, social)

Remember: length is a tactic, not a strategy.

Conclusion: Message Quality Beats Message Count

Don’t fall for the myth that shorter is always better—or that longer means more impact.

Your best bet? Start with clarity, focus on value, and choose the format that fits your message, not your assumptions. This blog post was written by a human and AI, working together to bring you the most insightful, efficient marketing advice.