The Perfect Cookie: Finding the Best Length for Successful Programs

One of the questions frequently asked by advertisers is “how long should my cookie length be?’ For our purposes today, the cookie length refers to the amount of time that a cookie will remain on a user’s machine after they have clicked an affiliate link to an advertiser’s site, unless it’s overwritten by another affiliate’s cookie.

Our research has shown that the majority of affiliate sales occur within 24 hours of the affiliate link being clicked, so how should this impact the cookie length offered to affiliates?

There could be an argument on one hand to reduced cookie length. With the majority of sales occurring within 24 hours, a reduction in the cookie length is highly unlikely to have an impact upon a publisher’s sales and ultimately earnings. However, if there is minimal impact doesn’t it make sense to extend cookie lengths? Again, as the majority of affiliate sales occur within 24 hours, there will be minimal impact on profit levels, but on the flip side, the program will look even more appealing to publishers.

There are some large programs using a 24-hour cookie, but this can be seen as unfair. So is it right that an affiliate has played a deciding role in closing a sale, but will not get rewarded for it unless the customer converted in a 24-hour window? This is even more questionable for advertisers who work on a single-session cookie—one notable online retailer using a single session cookie being Amazon—where an affiliate will only get recognition for generating the sale if the transaction takes place within the same session. In recognition of the affiliate’s role, the industry standard for cookie lengths stands at 30 days and is often accepted as the default length.

Some advertisers will extend their cookie lengths to appeal to publishers. They are safe in the knowledge they will rarely pay out on anything older than 30 days. Interestingly, prior to being bought by Amazon, Zappos had a 365-day cookie in place. This has consequently been reduced to 30 days since the acquisition. While a 365-day cookie may appeal to affiliates, it is questionable the influence an affiliate has had over a transaction that is completed so long after the initial click. Some cookies might outlast the device the transaction took place on!

As it is impossible to know everything about a user’s decision-making process and how long they spend researching their purchases, it is ultimately up to the advertiser to decide on the right cookie length for them. However, we’re in a position to advise advertisers on cookie lengths, and the following points should be considered.

Decision-Making Process—Cookie lengths should reflect the typical consumer decision-making process that is involved. Does the product under consideration require considerable research? If so, then a longer cookie period is required. It would be unreasonable to expect a publisher to close a sale within 24 hours of the initial click if it’s likely to be a more complex purchasing decision. For example, buying a CD could be considered an impulse buy whereas booking a holiday involves much greater thought, discussion, and planning.

Understanding Competitors—There are a number of affiliate programs vying for publisher attention. Publishers will therefore consider a number of metrics when deciding on who to promote. With onsite space at a premium, advertisers could differentiate their campaign by offering increased cookie lengths. Although evidence suggests this will have little impact in terms of actual sales, longer cookie lengths could be seen as positive PR and demonstrate commitment to recognizing affiliates’ worth.

To summarize, there are a number of factors that advertisers need to consider when setting cookie lengths. It’s important to bear in mind the product being sold and how the customer may behave prior to purchasing. Although longer cookie lengths may not have an impact on the number of sales an advertiser will have to pay out on, it can be utilized as positive PR for a program. Transparency is also key—this is not just in terms of how long the cookie length will be, but also extends to deduplication.

Whatever cookie length you decide upon, make sure that it is clearly stated within your program’s description.

About Matt Swan

As promised last week, attached please find the article on the value of strong conversion rates within the performance channel. This article was written by Matt Swan, Client Strategist for Affiliate Window.

3 Responses to The Perfect Cookie: Finding the Best Length for Successful Programs

  1. Gary says:

    I never really thought about these things before. But then again I am pretty new to affiliate marketing. I just recently signed up with Amazon. I cannot believe that they have a one session cookie timeout. You would think people would hate that, but for some reason people still make a ton of money off of them? 

  2. Professional SEO Services says:

    Oh, Really informative for me..!

  3. says:

    Very useful post. would consider to set the cookie length 30 days for affiliate program on our store.