I'm thinking of setting up an e-commerce store selling books for bitcoins, but waiting for the six confirmations to minimize my risk of a double spend attack. Does anyone know of any charts out there that list average confirmation time for the six confirmations to occur? My wish list for these charts: two charts, one that shows average amount of time to get six confirmations without any transaction fee, and another to show average amount of time with a transaction fee.
My concern is that I'm okay with waiting a day or two for the confirmations, but with typical e-commerce being instantaneous, customers would likely be frustrated and leave and I'd get no sales if this is common.
There are two separate questions here:
1. Once mined, the average time for 6 confirmations is, by design, going to be around hour. That is adjusted every, roughly, two weeks by the change in difficultly. The variance is an issue here of course, but it should be within 1-2 hours to get that many confirmations. Again, that is once mined.
2. The other question is what is the average time to get 6 confirmations
including the time between when the transaction is submitted and when it is first mined. That is dependent on a number of factors, including if a fee is paid, the priority of the transaction (which includes the size) etc. This would be the average time of one hour, plus the time waiting for the transaction to be mined. The statistics for how long it takes a transaction to be mined will vary as above. [Edit: e.g. this depends on the number of inputs, the number of bitcoins (e.g. if you are selling an antique book for 1000 Euro (4 BTC from one output), you will get a much faster confirmation than if it is 0.0004 BTC from 50 different outputs because of the priority. etc) ]
A few other notes:
a. if you are truly selling "books for bitcoins" (not ebooks or something electronic), you can afford to wait much longer since you will no doubt have many hours to confirm the transaction prior to shipping. Even if you waited a day to ship, that wouldn't be an issue. You can accept the order when submitted, and ship once the transaction confirms.
b. If you require payments to include appropriate fees, you will get a much faster confirmation. And you can say something like "transactions that do not include fees do not ship until confirmed. Transactions that include fees ship much faster."
Make sense?