Body language isn't 70%. Here's what the research actually says.

DRAFT for Fred to edit.

Sales trainers will tell you body language is 70% of communication. Others quote 7% words, 38% tone and 55% body. Engineers in the audience usually smell a rat. They’re right to.

Where the numbers come from

“Body language is 70%” traces back to the anthropologist Ray Birdwhistell, who estimated that words carry no more than 30 to 35% of meaning. It was an estimate, with no data behind it.

“7% / 38% / 55%” comes from Albert Mehrabian’s two small studies in 1967. People heard single words, like “dear” or “terrible”, said in a tone that contradicted them, or saw a face, and judged only whether the speaker liked them. Mehrabian has said himself that the figures don’t apply to communication in general.

What does hold up

1. When the channels conflict, voice and body win. If your words say “I’m confident” and your voice rises like a question, people believe the voice.
2. Voice carries more than we think. In a University of Chicago study, recruiters who heard a job pitch rated the candidate as more intelligent and more hireable than recruiters who read the same words.
3. When everything lines up, words carry the content. In technical work, what you say still matters most. It just has to be delivered in a way people believe.

A better way to think about it

Communication is made of three parts: words, voice and body. Words decide what people know. Voice decides whether they believe you. Body decides whether they trust you. Words alone aren’t enough, and you don’t need a fake percentage to prove it.

Try it: say “We can finish by Friday” four times, stressing a different word each time. Same words, four messages. Then record it in the practice room.