Audio ads for WhatsApp, Instagram and Facebook: length, format and volume

Most small businesses post photos and text on social media. Very few use sound, even though plenty of people watch stories and reels with the sound on, and a voice explaining the offer gets attention a photo doesn't.

The same spot you make for the radio or the sound truck can work on social media and in messaging apps, as long as it's cut and mixed for how people listen on a phone.

Where audio ads work

WhatsApp is less universal in the US than in other countries, but it's widely used by many communities, especially Spanish-speaking customers, immigrant communities and small-business groups. If a good share of your customers already message you there, it's worth using.

Length: shorter than you think

On a phone, people decide in two or three seconds whether to keep listening. For social media and messaging, 15 seconds is often enough, and 30 is the upper limit for most local offers.

At a natural pace, that's:

• 15 seconds: about 35 words.
• 30 seconds: about 70 to 75 words.

Start with the offer or the most interesting thing. The slow build-up that works on the radio doesn't survive the scroll.

Today only at Rosa's Bakery: a dozen glazed donuts for nine dollars. Rosa's Bakery, on Washington Street. Come by before noon.

Format: mono, light and at the right loudness

Mono

Phone speakers are small, and on many phones there's effectively one speaker doing most of the work. A stereo mix with the voice slightly to one side or music spread wide can sound unbalanced. A mono mix sounds the same on every phone.

File size

For messaging apps, a lighter file loads faster and plays immediately, even on a slow connection. A 30-second MP3 at a modest bitrate is small enough to send easily and still sounds clear on a phone speaker. You don't need studio quality for WhatsApp. You need a voice that's clear and a file that opens without waiting.

Loudness

Social platforms normalize audio so that every post plays at a similar level. The common target is around -14 LUFS (LUFS is a measure of perceived loudness). If your file is much quieter, it'll sound weak next to other posts. If it's much louder and distorted, the platform turns it down and the distortion stays.

SpotFacil has an output setting for each of these. For social media, the file is mixed to about -14 LUFS. For WhatsApp, it comes out mono and light. You choose the destination before you download.

Turning audio into a post

Instagram, Facebook and TikTok don't accept audio files alone. You need a video. The simplest version:

1. Take a photo of the product or the storefront.
2. Open the free video editor in your phone or the app itself (Instagram, CapCut, Canva).
3. Add the photo, set the duration to the length of the audio and add the audio file.
4. Add captions with the key words: the offer, the price, the name.

Captions matter. Some people will watch without sound, especially on Facebook. If the captions carry the offer, the post still works.

For more motion, use a few photos or a short clip of the product and lay the spot over it.

Sending on WhatsApp without spamming

WhatsApp is personal. A message that feels like spam gets you blocked or reported, which can limit your account.

Use WhatsApp Business. The free business app lets you set up a profile, catalog, quick replies and broadcast lists.

Only message people who agreed to it. Customers who gave you their number and said yes to offers. Ask at checkout or put a sign by the register.

Use broadcast lists, not groups. A broadcast list sends to each person individually. They only receive it if they've saved your number, which is a good filter. Groups expose everyone's numbers to each other.

Post on Status. WhatsApp Status works like stories. People who have your number see it if they want to. It's the least intrusive way to share an audio offer.

Don't overdo it. One or two promotional messages a week is plenty for most shops. Daily offers belong on Status, not in people's chats.

Pair the audio with text. Send a one-line text with the offer above the audio so people know what it's about before they press play.

This week: chicken thighs 99¢/lb at Garcia's Market. Listen for the details.

Voice note or audio file

WhatsApp treats audio in two ways. A voice note recorded in the app plays with the green waveform and feels personal. An audio file you send from your phone plays the same way in most cases, but may appear as an attachment depending on the format. MP3 files usually play inline. Test by sending one to yourself first.

Text messages and email

Some shops use SMS marketing platforms, which can include a link to the audio or a short video. Commercial texting in the US has its own consent rules, so use a platform that handles opt-in and opt-out, and check its requirements before sending.

For email, a link to the audio or a short video works better than an attachment.

Reusing the same spot everywhere

You don't need a different ad for every channel. Make one script and finish it for each destination:

In SpotFacil, the voice, music and effects stay the same. You change the destination and download again. The first spot, up to 30 seconds, is free.

Frequently asked questions

How long should an audio ad for WhatsApp be?

Between 15 and 30 seconds. Shorter is better for Status and broadcast lists. Put the offer in the first sentence.

What format should I use for WhatsApp audio?

A mono MP3 at a modest bitrate works well: small enough to load quickly and clear enough on a phone speaker. Send it to yourself first to check how it plays.

Can I post audio only on Instagram?

No. Instagram and Facebook need a video. Combine your audio with a photo or short clip in a free editor, and add captions with the offer.

What loudness should social media audio be?

Around -14 LUFS, which is the level most social platforms normalize to. Files that are much quieter sound weak, and files that are too loud get turned down.