<p><a href="https://bitcoin.stackexchange.com/users/2306/nick-odell">Nick Odell</a> answers <a href="https://bitcoin.stackexchange.com/questions/1823/what-is-the-maximum-size-of-a-transaction">the original question</a>: </p>

<blockquote>
  <p>The maximum transaction size is the size of the block. <a href="https://github.com/bitcoin/bitcoin/blob/3c098a8aa0780009c11b66b1a5d488a928629ebf/src/consensus/tx_verify.cpp#L166" rel="noreferrer">Source</a>.</p>
</blockquote>

<p>and</p>

<blockquote>
  <p>Transactions larger than 100 kilobytes (including witness at a 75% discount rate) are non-standard. <a href="https://github.com/bitcoin/bitcoin/blob/3c098a8aa0780009c11b66b1a5d488a928629ebf/src/policy/policy.h#L24" rel="noreferrer">Source 1</a>. <a href="https://github.com/bitcoin/bitcoin/blob/3c098a8aa0780009c11b66b1a5d488a928629ebf/src/net_processing.cpp#L661-L665" rel="noreferrer">Source 2</a>.</p>
</blockquote>

<p>so the case that you are describing will not occur as transactions lager than the blocksize will be sorted out. </p>

CC BY-SA 4.0
2019-03-04T12:14:18.037Z
2019-03-04T12:14:18.037Z
Rene Pickhardt
<blockquote>
  <p>what happens if size of a transaction is larger than maximum block size?</p>
</blockquote>

<p>Then the transaction can never be included in a block. </p>

<p>There is no mechanism for dividing it up into multiple blocks, or anything like that. Any block that includes it would be invalid, since the block would become too large for the network's rules.</p>

<p>This may be of interest: <a href="https://blockstream.info/block/000000000000000003dd2fdbb484d6d9c349d644d8bbb3cbfa5e67f639a465fe" rel="noreferrer">Block 364292</a> is 999.9kb, but it only has two transactions: the coinbase transaction, and a massive consolidation transaction with thousands of inputs. I believe that pre-segwit, thats about the largest transaction you could possibly include in a block.</p>

CC BY-SA 4.0
2019-03-04T12:29:18.417Z
2019-03-04T12:29:18.417Z
chytrik
<p>Assuming a <strong>transaction size</strong> is <code>T</code> Bytes, while <strong>maximum block size</strong> is <code>B</code> Bytes, such that <code>T&gt;B</code>.</p>

<p>What happens for this transaction?</p>

<p>It will be divided into two smaller parts and will be stored in two separate blocks? Or it will not be confirmed at all? Or A dynamic block size could be used ?</p>

<p><strong>P.S.</strong> Although, actually maximum block size is <strong>1 MB</strong> and seems to be enough for every transaction; however, we would like to know the strategy of the Bitcoin in such a situation. </p>

<p><strong>Note:</strong> Since in <a href="https://bitcoin.stackexchange.com/a/1824/41513"><strong>addressed answer</strong></a> is mentioned: "What limits transaction size is cost." the question does not seem to be the same, where my question is not what is the maximum size of a transaction, but is what happens if size of a transaction is larger than maximum block size.</p>

CC BY-SA 4.0
2019-03-04T12:09:57.757Z
Possible duplicate of [What is the maximum size of a transaction?](https://bitcoin.stackexchange.com/questions/1823/what-is-the-maximum-size-of-a-transaction)
Rene Pickhardt
CC BY-SA 4.0
2019-03-04T12:19:50.163Z
@Rene Pickhardt , Since in addressed answer is mentioned: _"What limits transaction size is cost."_ the question does not seem to be the same, where my question is not what is the maximum size of a transaction, but is what happens if size of a transaction is larger than maximum block size. Thanks
Questioner
CC BY-SA 4.0
2019-03-04T16:58:53.837Z
I feel this is not enough substance to be an answer, but generally things don't "happen" with a block. Transactions are included in blocks, or not, and the result must satisfy the network's rules. If there is no way to include a transaction in a block in a way that satisfies the rules, by definition it can't be included.
Pieter Wuille
CC BY-SA 4.0
2019-03-04T17:43:58.363Z
yeah I saw this which is the reason why I also referred to an answer from there. Also the rest of the community seems to agree with you. I wasn't sure but I guess that is why it is not one moderator deciding but a voting (:
Rene Pickhardt
<transaction-weight><block-weight>
What happens if "transaction size" is larger than "maximum block size"?
Questioner
# What happens if "transaction size" is larger than "maximum block size"?

(Asked by: username_0 on 2019-03-04)

Assuming a **transaction size** is `T` Bytes, while **maximum block size** is `B` Bytes, such that `T>B`.

What happens for this transaction?

It will be divided into two smaller parts and will be stored in two separate blocks? Or it will not be confirmed at all? Or A dynamic block size could be used ?

**P.S.** Although, actually maximum block size is **1 MB** and seems to be enough for every transaction; however, we would like to know the strategy of the Bitcoin in such a situation.

**Note:** Since in [**addressed answer**](https://bitcoin.stackexchange.com/a/1824/41513) is mentioned: "What limits transaction size is cost." the question does not seem to be the same, where my question is not what is the maximum size of a transaction, but is what happens if size of a transaction is larger than maximum block size.

**Tags:** transaction-weight, block-weight

> **Comments:**
> **username_1**: Possible duplicate of [What is the maximum size of a transaction?](https://bitcoin.stackexchange.com/questions/1823/what-is-the-maximum-size-of-a-transaction)  
> **username_0**: @username_1 , Since in addressed answer is mentioned: _"What limits transaction size is cost."_ the question does not seem to be the same, where my question is not what is the maximum size of a transaction, but is what happens if size of a transaction is larger than maximum block size. Thanks  
> **username_2**: I feel this is not enough substance to be an answer, but generally things don't "happen" with a block. Transactions are included in blocks, or not, and the result must satisfy the network's rules. If there is no way to include a transaction in a block in a way that satisfies the rules, by definition it can't be included.  
> **username_1**: yeah I saw this which is the reason why I also referred to an answer from there. Also the rest of the community seems to agree with you. I wasn't sure but I guess that is why it is not one moderator deciding but a voting (:  

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## 2 answers

### Answer by username_3 on 2019-03-04. Score: 6 | Accepted answer

> what happens if size of a transaction is larger than maximum block size?

Then the transaction can never be included in a block.

There is no mechanism for dividing it up into multiple blocks, or anything like that. Any block that includes it would be invalid, since the block would become too large for the network's rules.

This may be of interest: [Block 364292](https://blockstream.info/block/000000000000000003dd2fdbb484d6d9c349d644d8bbb3cbfa5e67f639a465fe) is 999.9kb, but it only has two transactions: the coinbase transaction, and a massive consolidation transaction with thousands of inputs. I believe that pre-segwit, thats about the largest transaction you could possibly include in a block.


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### Answer by username_1 on 2019-03-04. Score: 5

[Nick Odell](https://bitcoin.stackexchange.com/users/2306/nick-odell) answers [the original question](https://bitcoin.stackexchange.com/questions/1823/what-is-the-maximum-size-of-a-transaction):

> The maximum transaction size is the size of the block. [Source](https://github.com/bitcoin/bitcoin/blob/3c098a8aa0780009c11b66b1a5d488a928629ebf/src/consensus/tx_verify.cpp#L166).

and

> Transactions larger than 100 kilobytes (including witness at a 75% discount rate) are non-standard. [Source 1](https://github.com/bitcoin/bitcoin/blob/3c098a8aa0780009c11b66b1a5d488a928629ebf/src/policy/policy.h#L24). [Source 2](https://github.com/bitcoin/bitcoin/blob/3c098a8aa0780009c11b66b1a5d488a928629ebf/src/net_processing.cpp#L661-L665).

so the case that you are describing will not occur as transactions lager than the blocksize will be sorted out.


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