While most people jump to conclusions and speculate, we choose to follow the research on this long-debated topic. The general rule of thumb is that the more expensive and complex your product is, the longer your copy needs to be. Most expert copywriters agree that ad copy needs to be as long as it has to be to present the full story about your product. Sometimes this is 200 words, and other times it can be 5000 words.

If you have the time, we highly recommend you listen to the audio and read the complete study at marketingexperiments.com. Below is a brief excerpt from the study in which the authors summarize their findings:

Again, long copy outperformed short copy; this time by an even greater factor of nearly four to one. Our ROI was a dismal -66% for the short copy page and a very respectable 50% for the long copy page. In general, long copy offers the following advantages:

1. Your visitors will have most of their questions answered and will have less anxiety about ordering from you.

2. Long copy can reduce customer service by qualifying your customers to a greater degree.

3. Long copy with bolded or emphasized points can allow some of your visitors to skim, while others more interested in specifics can find all the information they want. In this sense, long copy gives visitors more options.

4. Long (and interesting) keyword-rich copy often performs well in natural search engines.

The article goes on to mention a few qualifiers on the use of long copy. The bottom line is that long copy should be a good copy, not verbose blather.

KEY POINT: The long vs. short debate often overlooks the most important factor when it comes to website copy: quality. High-quality short copy will outperform poorly-written long copy every time. The best possible copy should be developed and tested before you even begin to worry about the long vs. short debate.
When testing site copy, control your other variables. Page design, layout, graphics, etc. can all affect the performance of a page. So when testing copy, make sure the other page elements remain the same.
Utilize an A-B split test. This will ensure that other factors - such as time, traffic source, and so on - do not skew your results.

Copy should be long enough to do its job effectively, and not a word longer. Long copy for the sake of long copy is not to your benefit. Always keep in mind the primary goal of your website’s copy (to sell your product or service, solicit subscriptions, etc.).

There is really a paucity of research on this issue. But we can tell you from our experience with our campaigns that some businesses, like moving services, need only a form and very brief ad copy. Often, just a few testimonials will do the trick along with a good headline. Many branded commodity products need only minimal ad copy on a shopping cart page.

But if you are selling a high-priced item or if you are selling a service that is unique, you will need to use long ad copy to convey the entire value proposition to your visitors.

Long ad copy tends to work very well when selling the services of a professional. Most people want to establish some degree of trust with that professional before they call on the phone. Landing pages for a law firm will not be effective if you just have a picture and a lead form. You need to clearly show with specific examples and facts that a service professional has the talent, experience, and knowledge to give the value that the visitor is looking for.