What is 24-hour rule in WhatsApp Business API?

Understand the 24-hour messaging window rule and how it affects your replies and template usage.

The 24-hour rule (service window) lets you send free-form replies only within 24 hours of a user’s last message. Outside the window, you must use an approved template to restart the conversation.

Key takeaways

Inside 24 hours: you can reply with session messages (no template required).

Outside 24 hours: you must send a template to reopen the conversation.

Marketing, utility, and authentication templates each start a billable conversation.

What the 24-hour window means

The clock starts when a user messages you. You can send session replies for 24 hours from that timestamp without using a template.

When the window closes

You cannot send free-form messages after 24 hours.
To reach out, send an approved template (marketing, utility, or authentication).
A new conversation charge begins when you send that template.

Best practices

Set reminders before the window closes to ensure timely replies.
Use quick replies/bots to acknowledge users instantly.
Keep utility templates ready for follow-ups after the window.

FAQs

Can I send media in the session window?

Yes. Within 24 hours, you can send free-form text or media without a template.

Does the clock reset with each user message?

Yes. Each new user message restarts the 24-hour session window.

Can I send a marketing template after 24 hours?

Yes, any approved template type can reopen the conversation; the category sets the billing.