What is the maximum length of a Subflow message?

What’s the Maximum Message Length in Subflow?

Subflow uses SMS (Short Message Service) to deliver messages, which follows the GSM (Global System for Mobile Communications) standard. SMS messages are sent in 140-byte segments, typically allowing up to 160 characters per segment using GSM-7 encoding.

🟢 Subflow’s Recommendation

For best performance and deliverability, we recommend keeping your messages under 320 characters, which generally equals 2 message segments. Staying under this limit helps reduce delivery issues and keeps messaging costs low.

✏️ Character Limits & Encoding

• Standard Characters (GSM-7): Up to 160 characters per segment.

• Unicode Characters (like emojis): Use more data, often reducing the per-segment limit to 70 characters.

• Smart quotes, special symbols, and certain formatting characters may also reduce the character limit due to encoding changes.

💡 Pro tip: Avoid emojis unless they’re essential. Use straight quotes (") instead of smart quotes (“ ”) and remove extra formatting to maximize your character count.

🔔 Subflow Character Counter

Subflow includes a built-in character counter that alerts you when your message:

• Exceeds a single segment

• Is approaching maximum character limits

• Might be encoded in Unicode (due to emojis or special characters)

These indicators help you optimize messages before sending.

📄 Need to Send More?

If your content is too long for SMS, consider:

• Linking to a Subflow Page or hosted content

• Sending a shorter summary via SMS with a link to read more