Increase Sales, Conversions, And Profits With The “Rule Of Odds”

Why do we believe that in all matters the odd numbers are more powerful?
–Pliny the Elder, Natural History

I came across an interesting post yesterday by Dan Tudor about how using odd numbers is more profitable than using even numbers. After a little digging there seems to be a “rule of odds” in composition, which may serve as a general theory to the rule of three I mentioned in the past.

Copywriter Gymi Slezinger proposed a theory that

Even numbers have balance and closure. They don’t need you. Odd numbers have something hanging. There is urgency in them.”

When crafting a story you introduce conflict and then present a resolution to that conflict. A typical story will even propel you through to the end with a series of smaller conflicts and resolutions within the overall major conflict/resolution. The next time you read a thriller notice that many chapters will come to resolution prior to the last page of the chapter and then start another mini conflict to get you to turn the page.

Odd numbers carry the conflict and tension. Even numbers resolve the conflict. Odd numbers become more exciting and compelling as a result of the tension they inherently create.

The “rule of odds” in composition suggests that an odd number of subjects is more aesthetically pleasing and more interesting than an even number of objects. There is something to the asymmetry of odd numbers that people prefer to the symmetry of even numbers.

I’ve come across the rules of odds and threes time and again when studying both design and writing, but until today I hadn’t come across the idea that human-generated random numbers are usually odd.

When you ask a person to pick a random number, they’ll usually choose an odd number that doesn’t end in 5. As a side-effect, many human-generated random numbers are prime.

Oddly enough when I think of all the times someone has asked me to pick a random number I usually do choose an odd number. There’s probably a good party trick in there someplace where you predict what number someone “randomly” chooses.

Using The Rule Of Odds

The Psychology of Pricing mentions that “studies show that odd numbers are more commonly associated with lower prices than even numbers.” Make sure your prices end in an odd number. $9.99 instead of $9.98.

An obvious place to use odds is in lists. List 3 benefits instead of 4, 9 instead of 10. You may have noticed recently that the top 7 lists are now the new linkbait list number as opposed to top 10 lists. 10 resolves. 7 builds tension and excitement.

Group your tables in odd numbers of columns and/or rows and follow the rule of thirds when composing images for your site.

Divide your posts into an odd number of sections with an odd number of headings. Divide your pages into an odd number of groupings. Use three levels of membership instead of two or four. Let your sales run for seven days instead of two weeks.

Whatever you are doing keep asymmetry and odd numbers in the back of your mind. Those uneven numbers may just lead to more readers, conversions, and profits.

Uneven numbers are the gods’ delight.
–Virgil, The Eclogues


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  1. In relation to pricing, I have seen a few articles stating that ending a price with the odd number 7 somehow subconsciously makes the price seem smaller to people – even more effective than ending with 9. e.g., pricing something at $19.97 instead of $19.99. You might also notice that many of the “sales pages” (one page sales letters online) price their products at $37.77 or something similar.

  2. Chris I’ve seen that a lot too about the number 7. I’ve seen 7 mentioned because many consider it a lucky number. I get the feeling that’s cultural though, because I think there are cultures who see 7 as unlucky too. It would be an interesting experiment for anyone selling products. Change the $19.99 or $19.95 to $19.97 and see what happens.

    One of the articles I was reading on price while writing this post (I can’t remember if it’s the one I linked to or not) suggested that the number 9 was actually the best to use.

    What all the articles agreed on was that most people end up only paying attention to the first few digits of any price and drop the rest. So $9.99 because $9, which sounds cheaper than $10 even though it’s really not.

  3. Ha, that’s funny because I’ve always considered 7 my lucky number, and usually choose it when having to blurt out a ‘random number.’ This is a great study, perfect to be applied to almost anything. Thanks!

    • I don’t think you’re alone in considering 7 a lucky number. This would probably be hard to observe in yourself, but do you think you end up being more inclined to buy something when there’s a 7 in the price?

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