Long enough to do the job you have set for it.
It’s got to be long enough to include all of the elements of good copy: to capture their attention, garner their interest, develop their desire, remove doubt, and call them to a clear and specific action that moves them to buy.
Based on the law of averages, the longer the copy can hold the reader’s interest, the likelier you are to convince more of them to act.
The key is holding interest. Each sentence should have a specific purpose. You want the minimum viable copy that is necessary.
Most of the time, short copy does not push the reader far enough along the road to take action. All humans have doubts they have to overcome before they will buy, and the process of persuasion requires mountains of proof for the reader to the level of conviction and trust that allows them to buy.
The rare exception is if the reader is already aware of his problem, what the solution is, and how your product or service can provide resolution. That usually means they’ve been reading your content religiously and over a long period of time.
The point is to meet the reader where they are at, apply the architecture of persuasion, communicate all the relevant information, demonstrate value, answer all the objections, deliver on your headline, and DO ALL THAT IN AS FEW WORDS AS POSSIBLE.
How do you decide the best copy length?
