The WhatsApp 24-hour window: how it works and how to plan around it

Almost every surprise in WhatsApp Business comes from one rule. When a customer messages you, a 24-hour window opens in which you may reply with anything. Outside that window you may only send a message built from a template that Meta has reviewed and approved in advance.

This is not a pricing detail. It shapes what the channel is good for, how long approval takes, and why you cannot simply write a campaign the way you would write an email.

What starts and what resets the clock

• The customer messaging you starts it. Every subsequent customer message resets it to a fresh 24 hours.
• You messaging them does not. Sending a template and getting no reply leaves the window firmly closed.
• A reply to your template opens it. Which is why a well-designed template gives a reason to respond — it converts a template conversation into a free-form one.
• Clicking a link is not a reply. It has to be a message.

Inside the window: free-form text, images, documents, whatever the conversation needs. Outside it: templates only, no exceptions, and an attempt to send free-form simply fails.

What template approval actually involves

1. You submit the exact wording, with placeholders for the variables. Review typically takes minutes to a day and can be rejected.
2. You choose a category — marketing, utility or authentication. The category drives both policy and price, and Meta will re-categorise a template it thinks you have labelled wrongly.
3. Changes mean re-approval. A template is not editable in the way an email subject line is.
4. Quality is monitored. Templates that get blocked or reported are throttled or disabled, and a poor quality rating affects the whole number.

Plan for approval in your campaign timeline. A marketing calendar that assumes you can write the message the day before does not work on this channel.

Pricing follows the same structure

Meta has moved conversation-based pricing toward per-message charging for template messages, with rates varying by category and by country. Two consequences that matter more than the exact figures, which change:

• Marketing templates are the expensive category, and the one you will want to use most. Price the campaign per country before designing it.
• Free-form replies inside the window are the cheap part. A channel strategy that gets customers to start conversations is structurally cheaper than one that broadcasts at them.
• Utility templates — order updates, delivery notifications — are cheaper and get read. This is the most under-used part of WhatsApp for shops.

Opt-in is required and it is per channel

Meta's own policy requires opt-in before you send a template, obtained in a place where it is clear the customer is agreeing to receive WhatsApp messages from your business specifically. EU law says the same thing from a different direction: consent must be specific, and an email newsletter tick is not consent for messaging.

• A separate, unticked box naming WhatsApp.
• A recorded timestamp and source, as for every other channel.
• An opt-out honoured across every template, immediately.

What the channel is actually good at

Given the window and the approval process, the strongest uses are the ones with a natural reply:

1. Order and delivery updates that invite a question, which opens the window for support.
2. Back in stock for a specific product somebody asked about.
3. Post-purchase care — a how-to-use message that gets replies, which are the cheapest and most valuable conversations you will have.
4. A narrow, high-value win-back, priced deliberately, not broadcast.

What it is bad at is what email is good at: a weekly newsletter to everybody. The economics and the approval cycle both say so.