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How to write a 30-second audio ad

How many words fit in 30 seconds, where the brand goes, why one message and one call to action, and how to write for someone who can only hear the ad. With a worked example.

Hristijan Chris Jankulovski5 min read

A 30-second audio ad is one message, read calmly, with the brand named in the first sentence and the call to action as the last. That's the whole craft in one line. The rest is about keeping to it when you have more to say than 30 seconds can hold.

How many words fit in 30 seconds?

The platforms give two answers. Spotify's ad spec page says "no more than 65 words for a 30-second ad". Its best-practices guide and Google's audio ads help both say 60 to 80.

Treat those as ceilings for a quick, energetic read. For a calm voice with room to breathe between sentences, and a call to action that lands on its own, plan on about 45 to 50 words. That's a rule of thumb, not a platform rule, and the only way to check it is to read your script aloud against a timer at the pace you want it voiced. If you rush to make it fit, it's too long.

A 15-second ad holds about half: two or three short sentences.

Name the brand in the first five seconds

Spotify's guide is specific here: ads that mention the brand in the first five seconds "drive stronger favorability, message association, and intent", and it suggests making the brand name the last word of the opening sentence. A listener who drifts off after the first line should still know who it was.

Say the name again before the end. On a screen, the logo sits there for the whole ad. In audio, the name exists only while it's being said.

One message

Thirty seconds holds one idea. Spotify's guide suggests focusing on "one or two key messages and takeaways"; in practice, if you can't say what the ad is about in one sentence, the listener can't either. Pick the one thing (the taste, the offer, the problem it fixes) and give every sentence to it.

End on one call to action

Amazon's audio ad guidelines put it plainly: end with a clear statement of the action you want, with "one action per creative". Make the call to action the last sentence, keep it short, and make it something a listener can do later from memory: a name to search, an offer to ask for. Amazon also bans references to clicking, which makes sense, since nobody can click a sound.

Write for the ear

A reader can glance back; a listener can't. So:

  • Short sentences. One idea each. A sentence you need to breathe in the middle of is two sentences.
  • Concrete words. "Crunchy garlic and slow-fried chilies" plays better than "a premium flavor experience". The listener should be able to picture it.
  • No lists of numbers. A price, maybe. Specs, percentages, phone numbers and long web addresses don't survive one hearing.
  • Spell out how to say it. If the brand or a product name could be misread, write it the way it should sound for the voice.
  • Let the music sit under the voice. An instrumental bed that doesn't compete with the words; vocals in the music fight the script.

A worked example

A 30-second ad for a fictional chili crisp brand, 45 words:

Fonda chili crisp is the jar you'll reach for every night. Crunchy garlic, slow-fried chilies, and just enough heat. Spoon it over noodles, eggs, rice, even vanilla ice cream. It's made in small batches, and you can taste it. Order a jar of Fonda today.

The brand closes the opening sentence and comes back in the last line. Every sentence is about one thing, the taste. Nothing needs to be seen to make sense. And the last sentence is the only thing the listener is asked to do.

How Terrads writes audio ads

Terrads makes 15- and 30-second audio ads from your brand library: one voice over music, the way this post describes. You pick the length, the voice and the music's mood, and Terrads writes the scripts, up to three from different angles. Each is written to name the brand in its first sentence and again later, and to end on the call to action.

Nothing is voiced or charged until you've read the script. While you edit it, the script box tells you whether it fits the length ("Fits · about 27 s") or how far it runs over and what to cut. When you approve, you get the ad as an MP3, plus 9:16 and 1:1 videos of the same spot for the feeds where audio runs as video. Audio ads are in English for now.

Sources

Guidance quoted from each platform's page on 15 October 2026. For lengths, file types and loudness by platform, see audio ad specs by platform.