Amazon announced Kindle Unlimited, a new service that gives unlimited access to 600.000 books for $9.99/month.

The number sounds impressive, but even reading 1% of those books is close to a utopia. Underestimating and assuming that reading a book takes 1 day, reading 6.000 will take about 16 years. Moreover, so many choices can lead to SADD (Streaming Attention Deficit Disorder) - instead of reading a book from beginning to end, the reader gives up part way up and picks a new one, hoping to find something more exciting. This is a behavior observed only when the cost of change is less than the expected gain. In this case the cost is 0 (if you exclude the monthly fee) so surfing from book to book is extremely easy.

However, I’ve got excited while reading about the new service because it might help me save some money. Therefore, I’ve decided to do some math and figure out if this service is a good deal for me.

I like to read books and I do it in a particular way:

  • I only have one active book at a time. Otherwise, I cannot focus.
  • I do not buy books in advance unless they are on a great sale (75%+ discount).
  • I never start a new book until I finish the current one, unless it is really, really bad.
  • I don’t use audiobooks. The Amazon service includes them as part of the subscription.

For the calculation I am going to use the books that I read in the last 31 months (since Jan 2012). I’ve listed the books that I read in 2012 and 2013 but I am also giving a sneak peek into the books I read in 2014. What interests me is if the new Amazon service is a better deal for me than buying individual books. The rational buyer’s decision is very simple: if the cost of this new service is less than the cost of not having it then it is worth buying.

The table below shows the books that I read in the last 31 months. The price in the “Price today” column represents how much the book costs now (7/18/2014). The price in the “Paid” column is what I actually paid for that particular book. I paid less than the normal price for some of the books because I got them on discount or even for free from the public library.

Book title Price today Paid
The Adventures of Sherlock Holmes $0 (Free) $0 (Free)
Alice’s Adventures in Wonderland $0.99 $0 (Free)
A Journey to the Center of the Earth $0 (Free) $0 (Free)
We Die Alone: A WWII Epic of Escape and Endurance $9.99 $0.99
Bull Street $3.99 $1.99
The Snowball: Warren Buffett and the Business of Life $12.18 $0 (Library)
The Art of Being Unreasonable: Lessons in Unconventional Thinking $13.99 $11.99
Get A Financial Life: Personal Finance in Your Twenties and Thirties $9.08 $3.65
I Will Teach You To Be Rich $7.69 $2.24
The Accounting Game: Basic Accounting Fresh from the Lemonade Stand $9.99 $9.99
The Millionaire Next Door: The Surprising Secrets of America’s Wealthy $9.99 $0 (Library)
Fooled by Randomness: The Hidden Role of Chance in Life and Markets $9.37 $0 (Library)
The Intelligent Investor $5.29 $11.99
Total (2012) $92.55 $42.84
One Up On Wall Street: How To Use What You Already Know To Make Money In $9.12 $9.99
The 7 Habits of Highly Effective People: Powerful Lessons in Personal Change $9.99 $0 (Prime)
Harry Potter and the Philosopher’ Stone $5.99 $0 (Prime)
Harry Potter and the Chamber of Secrets $7.99 $0 (Prime)
Harry Potter and the Prisoner of Azkaban $7.99 $0 (Prime)
Harry Potter and the Goblet of Fire $9.99 $9.99
Harry Potter and the Order of the Phoenix $9.99 $9.99
Harry Potter and the Half-Blood Prince $9.99 $9.99
Harry Potter and the Deathly Hallows $9.99 $9.99
Broken Genius: The Rise and Fall of William Shockley $8.99 $8.98 (Paperback)
The Box: How the Shipping Container Made the World Smaller and the World Economy Bigger $9.48 $13.58 (Paperback)
Forrest Gump $9.99 $9.89
The Millionaire Mind $9.99 $0.99
Total (2013) $119.49 $83.39
For a Song and a Hundred Songs: A Poet's Journey through a Chinese Prison $5.99 $5.99
Moonwalking with Einstein: The Art and Science of Remembering Everything $8.62 $9.56
Caves of Steel (The Robot Series Book 1) $5.99 $5.99
The Naked Sun (The Robot Series Book 2) $5.99 $5.99
The Robots of Dawn (The Robot Series Book 3) $5.99 $5.99
The Ghost Map: The Story of London's Most Terrifying Epidemic--and How It Changed Science, Cities, and the Modern World $9.79 $8.59
The Four Pillars of Investing: Lessons for Building a Winning Portfolio: Lessons for Building a Winning Portfolio $16.50 $1.99
The Professor and the Madman $11.16 $1.99
Total (2014) $70.03 $46.09
Total (31 months) $310 $172.32

* Free = free book on Amazon. Prime = lent through Amazon Prime. Library = lent from the public library. Paperback = bought the physical book.

** The prices don’t include taxes

As you can see I spent $172.32 for all the books I read in the last 31 months. The Kindle Unlimited services is $310 for the same period. My average spending per month was ~$5.55. Also, in none of the two full years I’ve spent more than the cost of the yearly subscription.

Simply said getting the Amazon Kindle Unlimited service is not a rational decision for me and, for the time being, I will not subscribe to it.