The WhatsApp 24-Hour Window Explained (2026)

The WhatsApp 24-hour window is the period — starting from the moment a customer messages your business — during which you can reply with free-form (session) messages instead of pre-approved templates. It is also called the customer service window.

WhatsApp's model is built to protect users from spam: businesses cannot freely message people whenever they want. But when a customer reaches out first, they have clearly opted into a conversation, so WhatsApp opens a 24-hour service window in which your business can respond naturally — with text, images, buttons, lists, and more — without needing a template for every message.

Understanding this window is essential because it controls two things at once: what kind of message you can send and, in many cases, what it costs. This guide breaks down exactly what opens and closes the window, the difference between session messages and templates, and how to use the window to run cheaper, faster support. For the full pricing picture, see conversation vs. per-message pricing.

The window opens whenever a customer sends a message to your WhatsApp Business number. Every inbound message from that customer resets the clock to a fresh 24 hours.

Things that open or refresh the window:

• A customer sends you a text, photo, voice note, or any message.
• A customer taps a quick-reply or call-to-action button in your message.
• A customer replies to an automated template you sent.
• A customer messages you from a Click-to-WhatsApp ad or a wa.me link.

The trigger is always customer-initiated contact. Your own outbound messages do not open the window — only the customer's reply does. The moment that inbound message lands, you have 24 hours from that timestamp to respond freely.

The window closes automatically 24 hours after the customer's last message, unless they message again to reset it. Nothing you send keeps it open beyond that point.

Key facts about closing:

• The clock runs from the customer's most recent inbound message, not the first one.
• If the customer replies at hour 20, the window extends a fresh 24 hours from that reply.
• Your outbound messages do not extend the window.
• Once 24 hours pass with no new customer message, the window is closed.

After closing, you cannot send free-form messages. To re-engage the customer you must send a pre-approved template message, which is charged per message at its category rate and, once they reply, can reopen a service window.

Inside the window you send session (free-form) messages; outside it you must send pre-approved templates. This is the single most important distinction in WhatsApp messaging.

Session messages (inside the window):

• Free-form — any text, media, buttons, or lists you like.
• No pre-approval needed.
• Ideal for real conversations: answering questions, sending quotes, sharing files.

Template messages (outside the window, or to start a conversation):

• Must be pre-approved by Meta before use.
• Required to message a customer who hasn't contacted you in the last 24 hours.
• Used for notifications, reminders, marketing, and re-engagement.

Think of it this way: templates start or restart conversations; session messages continue them. If you are new to templates, our API guide and features page cover the building blocks.

Here is the practical difference between operating inside and outside the 24-hour window.

The takeaway: respond while the window is open, and you keep both your messaging flexible and your costs low.

Service messages exchanged inside the 24-hour window are free from Meta for the first 1,000 per number each month, while messages outside it are charged per Meta's category rate plus PayPerWA's flat fee. The window is therefore one of the biggest levers on your messaging bill.

Breaking down the cost on PayPerWA:

• Service messages in the window — Meta charge is free for the first 1,000 a month per number (Meta's service rate applies beyond that); PayPerWA's flat ₹0.20 (or $0.004 on USD wallets) per message applies to chatbot replies, and replies typed in the PayPerWA inbox carry no PayPerWA fee.
• Templates (outside the window or to start a chat) — Meta charges its category rate, e.g. India Marketing ₹0.86 or Utility ₹0.115; other countries vary — see our rates. PayPerWA adds its flat fee on top.
• No subscription — you pay per message, broken out transparently as Meta's charge + PayPerWA's flat fee.

Because Meta does not charge for the first 1,000 service messages a month per number inside the window, fast replies to inbound customer messages are the cheapest messaging you can do. See the full breakdown on our pricing page.

The cheapest way to run WhatsApp support is to reply to customers promptly while their 24-hour window is open, so you stay on service messaging (free from Meta for the first 1,000 a month per number) instead of paid templates. A few habits make a big difference.

Tactics to maximise the window:

• Respond fast — handle inbound queries within the 24 hours so you can use free-form session messages.
• Resolve in one window — gather details, answer, and close the loop before the clock runs out.
• Use buttons to invite replies — a quick-reply button that the customer taps both helps them and resets the window.
• Batch follow-ups — if you need to follow up after the window closes, do it with a single relevant template rather than several.
• Route to agents quickly — a fast handoff keeps the conversation (and the service window) alive.

For automated support, a chatbot that replies instantly keeps customers inside the window without manual effort.

The window shapes everyday support flows in concrete ways. Here are three common scenarios.

Example 1 — Order question. A customer messages "Where is my order?" at 2 PM. The window opens. Your team (or chatbot) replies with the live status, a tracking link, and a "Need anything else?" button — all session messages, free from Meta within the first 1,000 a month per number — before 2 PM the next day.

Example 2 — Window closed, re-engagement needed. A customer asked about a product two days ago and never replied. The window is long closed. To follow up, you send a single approved Utility or Marketing template ("Your item is back in stock"). When they reply, a fresh 24-hour window opens and you continue free-form.

Example 3 — Click-to-WhatsApp ad. A prospect taps your ad and messages "Tell me more". The window opens immediately, so your bot can answer questions, send a brochure, and qualify the lead — all within the free entry point window: reply within 24 hours and Meta charges nothing for up to 7 days.

The most common mistakes are misjudging when the window resets, trying to send free-form messages after it closes, and over-relying on templates when a fast reply would have been free (up to 1,000 service messages a month per number).

Watch out for these:

• Assuming your outbound messages keep it open — only the customer's inbound messages reset the clock.
• Letting the window lapse — delayed replies force you into paid templates for what could have been free in-window replies (the first 1,000 a month per number).
• Trying to free-form after closing — the message will fail or require a template; build your flows around this.
• Spamming templates — sending multiple templates to reopen a chat is costly and risks quality ratings.
• Ignoring opt-out — even inside a window, respect customers who ask to stop.

Design your support so the customer's natural replies keep the window alive, and reserve templates for genuine re-engagement.

PayPerWA automatically tracks each customer's 24-hour window and tells you whether you can send a session message or need a template — so you never have to calculate timestamps yourself. The platform manages the mechanics.

What PayPerWA does behind the scenes:

• Tracks the last inbound message per contact and knows when each window opened and will close.
• Indicates in the inbox whether a free-form reply is allowed or a template is required.
• Charges no PayPerWA fee on service replies your team types in the inbox (Meta is free for the first 1,000 a month per number, then charges its service rate), and applies Meta's category rate on templates.
• Lets chatbots reply instantly to keep customers inside the 24-hour window.
• Shows costs broken out as Meta's charge + PayPerWA's flat fee, with no subscription.

The result is cheaper support, fewer mistakes, and clear visibility. Create a free account to try it, or read the docs for how the window is exposed in the API.