Hello

On average, how many words are needed for a one-minute TV/radio ad?

Thank you

In only twenty seconds one can say a lot. You might find thirty seconds more than ample time to get the message across.
TV is a different ball game because of the complexity of pictures.
Since I'm familiar with radio only I can't give a guesstimate because you may say a lot but after the chopping of unwanted sentences you'll find ten seconds enough for the whole message.
I can only suggest you visit university radio stations as they will give more accurate guesses than anyone here. They might also allow you record the advert if you ask nice enough.

meobizy:
In only twenty seconds one can say a lot. You might find thirty seconds more than ample time to get the message across.
TV is a different ball game because of the complexity of pictures.
Since I'm familiar with radio only I can't give a guesstimate because you may say a lot but after the chopping of unwanted sentences you'll find ten seconds enough for the whole message.
I can only suggest you visit university radio stations as they will give more accurate guesses than anyone here. They might also allow you record the advert if you ask nice enough.

Thanks a lot for this brilliant suggestion, bro