<p><strong>SegWit2x</strong> is a combination of both <strong>SegWit</strong> and a <strong>2MB hardfork</strong> (to activate three months after SegWit). </p>

<p><strong>SegWit2x</strong> uses a different 'bit' for signaling (bit 4 instead of bit 1) than <strong>SegWit</strong>.</p>

<p><strong>SegWit</strong> (BIP141) is not activated at the moment because it requires <strong>95% of the mining hashrate</strong>, and not enough miners support <strong>SegWit</strong> at the moment, because some miners want a hardfork to increase the blocksize. To work around this the proposal of BIP148 allows users to force the miners to mine <strong>SegWit</strong> blocks by orphaning other blocks after August 1, 2017. BIP149 is a similar proposal, but will activate 11 months later. The vast majority of the core developers <a href="https://en.bitcoin.it/wiki/Segwit_support" rel="noreferrer">prefer BIP141 but most find BIP148 and BIP149 acceptable alternatives</a>. </p>

<p><strong>SegWit2x</strong> differs in implementation because of the activation of the <strong>2MB hardfork</strong> and the lower activation threshold of <strong>80% of the mining hashrate</strong>. <strong>SegWit</strong> (BIP141/BIP148/BIP149) itself has been developed by dozens of developers for over a year, has been tested extensively and has been ready for activation for some time now. It also has been successfully activated in Litecoin already. <strong>SegWit2x</strong> however is being developed at the time of writing by just a few non-core developers, although <strong>SegWit2x</strong> aims to be 'minimalistic', some people still consider this a risk because there is only a few months for development and only 2 weeks for testing.</p>

<p>At the time of writing the percentage of blocks signaling support for <strong>SegWit2x</strong> is at <strong>78% of the mining hashrate</strong>: 
<a href="https://blockchain.info/charts/nya-support" rel="noreferrer">https://blockchain.info/charts/nya-support</a></p>

CC BY-SA 3.0
2017-06-22T19:46:15.120Z
+1 While I feel that this answer is accurate, it could be improved by adding corroborating evidence for "some miners want a hardfork", "tested extensively", and "some people still consider this a risk".
Murch
CC BY-SA 3.0
2017-06-26T23:29:21.427Z
bit 4 of version?
Sig Touri
CC BY-SA 3.0
2017-06-27T06:42:09.843Z
@SigTouri: Bit 4 of the version bits. See [What are version bits?](https://bitcoin.stackexchange.com/q/39216/5406)
Murch
CC BY-SA 3.0
2017-07-13T08:49:58.127Z
So which BIP is SegWit 2x?
Josh
CC BY-SA 3.0
2017-07-18T01:15:59.687Z
@Josh SegWit2x is BIP91 which forces signaling for BIP141 but only 80% is required (versus 95%), combined with BIP102 - a hard fork to 2MB to happen 144*90 blocks after SegWit activates
Albert S
CC BY-SA 3.0
2017-10-15T00:00:06.803Z
Is my understanding correct? Segwit was activated on **August 23rd 2017** [c.f. article from CoinDesk](https://www.coindesk.com/50-blocks-segwit-bitcoins-coming-upgrade-blockchain-game-changer/), and the switch to 2MB will happen at the end of November [c.f. article from Forbes](https://www.forbes.com/sites/laurashin/2017/07/25/why-november-will-be-the-real-test-for-bitcoin/#3b1f60734c91)
Adriano
CC BY-SA 3.0
2017-06-21T03:23:42.553Z
2017-06-23T15:13:08.487Z
2017-06-23T15:13:08.487Z
Wouter
<p>Today everybody got the news about the potential segwit2x adoption. However, I am trying to understand:
while both of them based on the same segwit principals how they are different? Is it about the blocksize, signaling or is it about the implementation?</p>

<segregated-witness><segwit2x>
How is segwit2x different from segwit?
Sig Touri
# How is segwit2x different from segwit?

(Asked by: username_0 on 2017-06-20)

Today everybody got the news about the potential segwit2x adoption. However, I am trying to understand:
while both of them based on the same segwit principals how they are different? Is it about the blocksize, signaling or is it about the implementation?

**Tags:** segregated-witness, segwit2x


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## 1 answers

### Answer by username_1 on 2017-06-21. Score: 29 | Accepted answer

**SegWit2x** is a combination of both **SegWit** and a **2MB hardfork** (to activate three months after SegWit).

**SegWit2x** uses a different 'bit' for signaling (bit 4 instead of bit 1) than **SegWit**.

**SegWit** (BIP141) is not activated at the moment because it requires **95% of the mining hashrate**, and not enough miners support **SegWit** at the moment, because some miners want a hardfork to increase the blocksize. To work around this the proposal of BIP148 allows users to force the miners to mine **SegWit** blocks by orphaning other blocks after August 1, 2017. BIP149 is a similar proposal, but will activate 11 months later. The vast majority of the core developers [prefer BIP141 but most find BIP148 and BIP149 acceptable alternatives](https://en.bitcoin.it/wiki/Segwit_support).

**SegWit2x** differs in implementation because of the activation of the **2MB hardfork** and the lower activation threshold of **80% of the mining hashrate**. **SegWit** (BIP141/BIP148/BIP149) itself has been developed by dozens of developers for over a year, has been tested extensively and has been ready for activation for some time now. It also has been successfully activated in Litecoin already. **SegWit2x** however is being developed at the time of writing by just a few non-core developers, although **SegWit2x** aims to be 'minimalistic', some people still consider this a risk because there is only a few months for development and only 2 weeks for testing.

At the time of writing the percentage of blocks signaling support for **SegWit2x** is at **78% of the mining hashrate**:
<https://blockchain.info/charts/nya-support>

> **Comments:**
> **username_2**: +1 While I feel that this answer is accurate, it could be improved by adding corroborating evidence for "some miners want a hardfork", "tested extensively", and "some people still consider this a risk".  
> **username_0**: bit 4 of version?  
> **username_2**: @username_0: Bit 4 of the version bits. See [What are version bits?](https://bitcoin.stackexchange.com/q/39216/5406)  
> **username_3**: So which BIP is SegWit 2x?  
> **username_4**: @username_3 SegWit2x is BIP91 which forces signaling for BIP141 but only 80% is required (versus 95%), combined with BIP102 - a hard fork to 2MB to happen 144*90 blocks after SegWit activates  
> **username_5**: Is my understanding correct? Segwit was activated on **August 23rd 2017** [c.f. article from CoinDesk](https://www.coindesk.com/50-blocks-segwit-bitcoins-coming-upgrade-blockchain-game-changer/), and the switch to 2MB will happen at the end of November [c.f. article from Forbes](https://www.forbes.com/sites/laurashin/2017/07/25/why-november-will-be-the-real-test-for-bitcoin/#3b1f60734c91)  

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