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Consider the transaction 948a427.. which has 3341 confirmations as of now:
We can see that the time the relay is received at 8:36:30 and it has one confirmation at 08:50:04 (after 14 minutes).
How do we find out the exact time when it has 3 confirmations?
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The first confirmation was in block 298902, so the third confirmation was with block 298904, which is timestamped as 2014-05-03 09:42:49 (66 minutes after it was first received).
However, this timestamp is later than the one in the block after it, suggesting that a timestamp was pretty far off. As Matthieu's answer shows, blockcypher.com's API includes the time that they first saw the transaction. This suggests that the actual time three confirmations was reached was around 2014-05-03T09:31:55.867Z, approximately 59 minutes after the transaction was created (since it was relayed by Blockchain.info, I'm assuming the transaction timestamp there is accurate).
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As answered by Tim S. the 3rd confirmation is on block 298904. But the received time on blockchain.info is mostly inaccurate, see:
http://api.blockcypher.com/v1/btc/main/blocks/298902 http://api.blockcypher.com/v1/btc/main/blocks/298904 http://api.blockcypher.com/v1/btc/main/blocks/298905
So 298904 was received at 9:31:55 while 298905 was received at 9:32:04.
That's what I'd thought initially, but that doesn't seem right, because block 298905 is 10 minutes before block 298904... it seems to suggest that I've got 4 confirmations before I had 3?
– Pacerier – 2014-05-23T14:04:25.4631
A timestamp is incorrect, probably the one on 298904. There are certain rules for enforcing timestamp correctness, but they have some leeway. (each block references the one before it, so it's quite impossible to have blocks come in out of order)
– Tim S. – 2014-05-23T14:12:43.907Do you mean that we have to guess the timing of the confirmations? Shouldn't there be a better way, for example, querying blockchain.info of the time when it receives the broadcast? – Pacerier – 2014-05-23T14:16:29.037
Yes, that would be good. No, blockchain.info doesn't appear to record that. In fact, I assumed this is what their "Received Time" field should mean. But apparently it's just a repeat of the "Timestamp" field. Perhaps this is due to a simple mistake, which could be fixed for future (maybe also past) blocks. I'll see if I can report this as a bug... – Tim S. – 2014-05-23T14:43:36.633
1Besides blockchain.info, Are there any other alternatives we can rely on to get this information (timing when block is received)? I do not ask for exact timing, but in-order sequential timing of blocks is crucial. Basically it doesn't make sense if the timing for the 4th confirmation is before the 3rd confirmation.... – Pacerier – 2014-05-23T14:57:29.887
I checked several; they all reported only the timestamp as reported in the block itself. – Tim S. – 2014-05-23T15:19:39.140
So if what I need is sequential timing, I'm out of luck? – Pacerier – 2014-05-23T15:39:42.863
If you want it to be based on existing blockchain explorer sites that I've seen? Yes, you're out of luck. If you hit an API, you might be able to do something, e.g. with bitcoind), e.g. by querying it for the latest block number every x seconds (this could be suitable for future transactions, not past ones).
– Tim S. – 2014-05-23T15:51:11.190blockchain.info also has an API, which probably could tell you something as simple as the block number quite easily (might have more overhead and worse reliability than a local bitcoind server). – Tim S. – 2014-05-23T15:54:45.973
I've just noticed some oddity. Blockcypher claims that it received the transaction broadcast at
– Pacerier – 2014-05-24T18:38:43.7378:50:25http://api.blockcypher.com/v1/btc/main/txs/948a4275c9283110e915cbf51eec6831b4736b01dd2f10f084bb95e46aee1f36, but blockchain.info claims that it received the transaction broadcast at8:36:30.... So it took 14 minutes for blockcypher to receive the broadcast from blockchain.info? (I'd thought usually its a matter of seconds up to a few few minutes at most right?)The timestamps listed by Blockcypher approximately match the timestamps for the block, not the transaction itself. Either they don't try to show the time they first received the transaction, or they didn't happen to see this transaction until it came in the block (although normally, you're right, it should be just seconds before they see it). – Tim S. – 2014-05-24T18:49:38.877
@TimeS, The docs claim that it is the time when they received it, on their servers. Exact words from http://dev.blockcypher.com/#transactions: "When the transaction was received by BlockCypher servers.". Also, I've just tested it with transaction 83b1f... . According to http://time.is/ , I did the payment on blockchain.info at
– Pacerier – 2014-05-24T19:01:22.68318:52:20. Blockchain.info correctly shows the received time as18:52:21http://goo.gl/O1Hif4 and blockcypher correctly shows received time as18:52:21http://goo.gl/xEP8I9 . Why is there a 14 minutes delay in receiving previously?