Understanding the Bitcoin Segwit2x Fork Dates and Block Number
The Bitcoin Segwit2x fork happened at block 494,784. This block occurred on Nov. 17. Anyone with Bitcoin before the block now has equal parts Segwit2x. With forks, the block matters, not the date.
This block can be confirmed on the Segwit2x GitHub.
ON CLAIMING SEGWIT2x: If you were in for that block, you now have 1 Segwit2x for every Bitcoin that was in your possession when the block occurred. You don’t have to claim your Segwit2x coins right away to have ownership of them, if you have your private keys or were in a wallet/exchange that supports the block, you own Segwit2x. As we learn more we will offer directions for claiming coins (see wallet/exchange specific directions on the official sites of the specific wallets and exchanges). See our post-fork update on Segwit2x.
UPDATE: The Segwit2x fork was officially called off on November 8th. However, the Segwit2x fork still occurred (according to Coinbase and other sources). See Coinbase’s update. Block 494,784 was still the snapshot block (as originally announced). That block occurred early morning Pacific Time Nov. 17. Meanwhile, a second iteration of Segwit2x was said to have occurred in December.
HOW TO “BE IN FOR THE SNAPSHOT” ON A HARD FORK: To ensure you get “free coins” when a coin forks, like it did with Segwit2x, you must be in possession of Bitcoin in a wallet or exchange that is embracing the fork, or be in a wallet where you own your private keys BEFORE the block (if your Bitcoins aren’t recorded on the blockchain before the fork, then you won’t have your Segwit2x for example).
TIP: Consider holding your Bitcoin after the fork until there is confirmation that there are no issues (for example issues with Segwit2x not having replay protection).
—– the article below is the original article with minor edits, the above was edited heavily as events unfolded to reflect the current situation —-
In other words, the snapshot block number for Segwit2x is 494,784. Meanwhile, the snapshot date is approximately
Nov. 16 Nov. 17… but that date is subject to change and is only an approximation of when block 494,784 will occur (it has no other significance to the fork aside being a good guess as to when block 494,784 will happen).
That is really all there is too it. If you are in a wallet or exchange that supports the fork at block 494,784, then you will have 1 Bitcoin Segwit2x for every Bitcoin you own.
The only caveat is that each exchange or wallet that doesn’t let you control your private keys directly might have its own rules.
Thus, if you want full and immediate access to Segwit2x coins with no extra rules, then make sure you are in direct control your private keys when block 494,784 occurs (the simplest way to do this is to be in a full node wallet like Bitcoin Core).
NOTE: Given the way the blockchain works, you don’t have to be in Bitcoin early or stay late. That is, you don’t have to be in for block 494,783 or block 494,785. However, this is only true if you control your private keys directly. Third parties, like Coinbase, have special rules that augment that rule. For example, with Coinbase you’ll essentially need to be in 24 hours before the block and after the block, as Coinbase is disabling Bitcoin transactions for 48 hours surrounding the block. Thus, the block still matters with Coinbase, but special rules apply. So to say this once before I say it again, READ THE FAQ of whatever entity you use to better understand the specific rules of that entity.
What happens when the Segwit2x fork occurs? The fork will temporarily (or perhaps even permanently) result in two Bitcoin blockchains (and therefore two different “Bitcoins”). Entities such as Coinbase will list these two different coins under two different names. For Coinbase for example, the current bitcoin blockchain will be refereed to as Bitcoin (BTC) and the forked blockchain as Bitcoin2x (B2X). Each exchange/broker/wallet might handle the fork in a different way. So read the FAQ for the source you use.
TIP: One simple way to keep track of what block we are at is with blockexplorer.com. A block is mined roughly every 10 minutes, but this fluctuates (which is why one can only estimate the exact time a block will occur).