Confused about the DynamoDB billing

Question

Hi, 
A week ago, I asked the question about DynamoDB but I am still confused with it. (Sorry that I lost that account and con not login in.)
Below pic. is my billing info:
![DynamoDB billing info.](/media/postImages/original/IMMKmLcYoTSMWZLSQwXS_dVQ)
We have only two tables and the setting is showed below:
![table setting](/media/postImages/original/IMa_Ovj5WmQzmA_8N729cBSw)
No other additional info settings and no auto scale. The expected cost that we calculated is $0 because that we did not use more than the free tier.
We set 5 RCU and 5 WCU for the table2. Is that meaning we have 5*60*60=18000 ReadCapitalUnit-Hrs and 18000 WriteCapitalUnit-Hrs? If the answer is right, what is 594 ReadCapitalUnit-Hrs showed in the billing? Does it mean that we run out all the free usage and 594 ReadCapitalUnit-Hrs is our additional usage?
Another question is that if I set a 25 RCU and 25WCU provisioned table, and I have 1,000,000 items recorded in the table, and every item’s size is less than 1 KB.  is that mean every time I read it spend 1,000,000 * 0.5 / 25(consistently read) / 60 /60 = 2.78 hours to read? 
About the write usage, Is 25 WCU meaning that at most 64,800,000(25*60*60*24*30) items can be recorded in one month?
The last question is about the "Estimated cost $2.91 / month" showed in the pic below. Does this amount reduce the free usage?
![在此輸入圖片描述](/media/postImages/original/IM5_mVLYdHTxygfkPNbVOt7w)

Sorry that I have a lot of questions.
Thanks for the help!

Best,
Wilma

Answer

Here's a link to your recent question on the same topic: https://repost.aws/questions/QU4w4PagqNTwWkfeorcmTutw

You were advised to reach out to [Customer Services](https://aws.amazon.com/contact-us/) and use Billing Support. That's the best path when you have a billing question. They can tell you why you see what you see.

Confused about the DynamoDB billing

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