<p><strong>Scripts to find it out yourself + preprocessed data</strong></p>
<p>I have uploaded scripts that extract most of the data you ask at: <a href="https://github.com/cirosantilli/bitcoin-strings-with-txids" rel="nofollow noreferrer">https://github.com/cirosantilli/bitcoin-strings-with-txids</a> including the top 10k transactions for each category.</p>
<p>Those scripts rely on <a href="https://github.com/alecalve/python-bitcoin-blockchain-parser" rel="nofollow noreferrer">https://github.com/alecalve/python-bitcoin-blockchain-parser</a> which parses the blockchain data offline and without the need for a running local server.</p>
<p>The scripts could quickly update the data at any time efficiently from the last snapshot, and this is what I've found when I last updated on February 2021:</p>
<ul>
<li><p>byte size: list at <a href="https://github.com/cirosantilli/bitcoin-strings-with-txids/blob/master/data/tx_size_bytes" rel="nofollow noreferrer"><code>data/tx_size_bytes</code></a>: <a href="https://www.blockchain.com/btc/tx/bb41a757f405890fb0f5856228e23b715702d714d59bf2b1feb70d8b2b4e3e08" rel="nofollow noreferrer"> bb41a757f405890fb0f5856228e23b715702d714d59bf2b1feb70d8b2b4e3e08</a> (Jul 2015) with 999,657 bytes, it regroups a bunch of smaller outputs into one big one. The values are small, so it's likely made for the data and not value.</p>
<p>This transaction is sometimes dubbed &quot;The Megatransaction&quot;, and is mentioned e.g. at:</p>
<ul>
<li><p><a href="https://en.bitcoin.it/wiki/July_2015_flood_attack" rel="nofollow noreferrer">https://en.bitcoin.it/wiki/July_2015_flood_attack</a>:</p>
<blockquote>
<p>The July 2015 flood attack was a large &quot;stress test&quot; of the Bitcoin network. The possibly distributed attack has provoked hundreds of thousands of transactions, leaving over 80,000 in the mempool at one time. The attack is subsequent to stress tests executed in June.</p>
</blockquote>
</li>
<li><p><a href="https://bitcoin.stackexchange.com/questions/59986/longest-time-verifying-block">Longest-time-verifying block</a>: unsurprisingly it also took the longest to verify</p>
</li>
</ul>
</li>
<li><p>number of inputs: <a href="https://github.com/cirosantilli/bitcoin-strings-with-txids/blob/master/data/tx_nins" rel="nofollow noreferrer"><code>data/tx_nins</code></a>: <a href="https://www.blockchain.com/btc/tx/f2e197a6d8d088b13afd0f99d4027da36a9413b9f3d7730ba5278132ebc950a7" rel="nofollow noreferrer">f2e197a6d8d088b13afd0f99d4027da36a9413b9f3d7730ba5278132ebc950a7</a> (Aug 2015) + 8 other tied with 20,000</p>
</li>
<li><p>number of outputs: <a href="https://github.com/cirosantilli/bitcoin-strings-with-txids/blob/master/data/tx_nouts" rel="nofollow noreferrer"><code>data/tx_nouts</code></a>: <a href="https://www.blockchain.com/btc/tx/dd9f6bbf80ab36b722ca95d93268667a3ea6938288e0d4cf0e7d2e28a7a91ab3" rel="nofollow noreferrer">dd9f6bbf80ab36b722ca95d93268667a3ea6938288e0d4cf0e7d2e28a7a91ab3</a> (Jan 2016) with 13,107 outputs. Some of them have been spent, so it is not all just data embedding</p>
</li>
</ul>

CC BY-SA 4.0
2021-04-13T21:04:46.897Z
2023-05-08T07:38:41.717Z
2023-05-08T07:38:41.717Z
Ciro Santilli OurBigBook.com
<p>The largest transaction by size to date was the <a href="https://blockchair.com/bitcoin/transaction/bb41a757f405890fb0f5856228e23b715702d714d59bf2b1feb70d8b2b4e3e08" rel="nofollow noreferrer">Mega Transaction</a> mined by f2pool on 7 July 2015:
It was 999,657 bytes, had 5,569 inputs and 1 output.</p>
<p>The transaction filled a complete block by itself and that block was widely cited as taking 25 seconds to validate. The transaction caused a lot of discussion back then, and prompted e.g. this <a href="https://rusty.ozlabs.org/?p=522" rel="nofollow noreferrer">blog post about the Mega Transaction's validation time by Rusty Russell</a>.</p>

CC BY-SA 4.0
2019-01-18T01:02:01.197Z
2020-08-30T18:19:08.470Z
2020-08-30T18:19:08.470Z
Murch
<p>i found transactions with 20,000 inputs
<a href="https://blockchain.info/tx/cf1032c2213e6faea04f1813aa6890e7f588bb378cb98e7425aec83c11d4457c" rel="nofollow noreferrer">cf1032c2213e6faea04f1813aa6890e7f588bb378cb98e7425aec83c11d4457c</a>
<a href="https://blockchain.info/tx/30b3b19b4d14fae79b5d55516e93f7399e7eccd87403b8dc048ea4f49130595a" rel="nofollow noreferrer">30b3b19b4d14fae79b5d55516e93f7399e7eccd87403b8dc048ea4f49130595a</a>
<a href="https://blockchain.info/tx/f2e197a6d8d088b13afd0f99d4027da36a9413b9f3d7730ba5278132ebc950a7" rel="nofollow noreferrer">f2e197a6d8d088b13afd0f99d4027da36a9413b9f3d7730ba5278132ebc950a7</a>
<a href="https://blockchain.info/tx/8dabbf51f78c1e7286866af1de403118c5ddbe57ca93b54859245916d2bf1063" rel="nofollow noreferrer">8dabbf51f78c1e7286866af1de403118c5ddbe57ca93b54859245916d2bf1063</a>
<a href="https://blockchain.info/tx/740ac533882221099e7202bbdafbb99ec589c6e74fd2fe7ca1274b46ea4f0a96" rel="nofollow noreferrer">740ac533882221099e7202bbdafbb99ec589c6e74fd2fe7ca1274b46ea4f0a96</a>
<a href="https://blockchain.info/tx/dd6067e71c04cb62f8e5aa52ecc99b01ffcd551a52727d046a2fabb14eb39b4d" rel="nofollow noreferrer">dd6067e71c04cb62f8e5aa52ecc99b01ffcd551a52727d046a2fabb14eb39b4d</a></p>

CC BY-SA 3.0
2018-02-08T19:15:36.010Z
2018-02-08T19:15:36.010Z
Albert S
<ol>
<li><p>The largest single transaction to date is 465,554 bytes.  It's hash is <a href="https://blockchain.info/tx/659135664894e50040830edb516a76f704fd2be409ecd8d1ea9916c002ab28a2" rel="noreferrer">659135664894e50040830edb516a76f704fd2be409ecd8d1ea9916c002ab28a2</a>.</p></li>
<li><p>The same transaction has the largest number of inputs: 2,585.</p></li>
<li><p>Two transactions tie for the largest number of outputs: <a href="https://blockchain.info/tx/623463a2a8a949e0590ffe6b2fd3e4e1028b2b99c747e82e899da4485eb0b6be" rel="noreferrer">623463a2a8a949e0590ffe6b2fd3e4e1028b2b99c747e82e899da4485eb0b6be</a> and <a href="https://blockchain.info/tx/5143cf232576ae53e8991ca389334563f14ea7a7c507a3e081fbef2538c84f6e" rel="noreferrer">5143cf232576ae53e8991ca389334563f14ea7a7c507a3e081fbef2538c84f6e</a> both have 3,075 outputs</p></li>
<li><p>The same two transactions have the largest number of inputs plus outputs, although they only have a single input so the total is 3,076 inputs plus outputs.</p></li>
</ol>

<p>Note, however, that the blockchain has been used to store information by manipulating output addresses so it is more than likely that the transactions listed in 3) are not "real", in that they do not contain spendable outputs.</p>

CC BY-SA 3.0
2015-01-06T21:02:45.873Z
Limits on transaction sizes suggest that it would be hard to create a transaction this big nowadays. There is a 100K limit on "standard" transactions [See here](https://github.com/bitcoin/bitcoin/blob/master/src/main.h#L57)
Richard Kiss
CC BY-SA 3.0
2013-06-09T12:42:31.053Z
2013-06-09T12:42:31.053Z
jgm
<p>Disregarding value, but instead going by size in the protocol, what are the largest transactions so far in the history of Bitcoin, in terms of:</p>

<ol>
<li>byte size</li>
<li>number of inputs ("vin")</li>
<li>number of outputs ("vout")</li>
<li>total number of inputs and outputs</li>
</ol>

<transactions><blockchain>
By byte size and number of inputs/outputs, what are the largest transactions in the block chain so far?
Quizzical
# By byte size and number of inputs/outputs, what are the largest transactions in the block chain so far?

(Asked by: username_0 on 2013-06-08)

Disregarding value, but instead going by size in the protocol, what are the largest transactions so far in the history of Bitcoin, in terms of:

1. byte size
2. number of inputs ("vin")
3. number of outputs ("vout")
4. total number of inputs and outputs

**Tags:** transactions, blockchain


---

## 4 answers

### Answer by username_4 on 2013-06-09. Score: 5 | Accepted answer

1. The largest single transaction to date is 465,554 bytes. It's hash is [659135664894e50040830edb516a76f704fd2be409ecd8d1ea9916c002ab28a2](https://blockchain.info/tx/659135664894e50040830edb516a76f704fd2be409ecd8d1ea9916c002ab28a2).
2. The same transaction has the largest number of inputs: 2,585.
3. Two transactions tie for the largest number of outputs: [623463a2a8a949e0590ffe6b2fd3e4e1028b2b99c747e82e899da4485eb0b6be](https://blockchain.info/tx/623463a2a8a949e0590ffe6b2fd3e4e1028b2b99c747e82e899da4485eb0b6be) and [5143cf232576ae53e8991ca389334563f14ea7a7c507a3e081fbef2538c84f6e](https://blockchain.info/tx/5143cf232576ae53e8991ca389334563f14ea7a7c507a3e081fbef2538c84f6e) both have 3,075 outputs
4. The same two transactions have the largest number of inputs plus outputs, although they only have a single input so the total is 3,076 inputs plus outputs.

Note, however, that the blockchain has been used to store information by manipulating output addresses so it is more than likely that the transactions listed in 3) are not "real", in that they do not contain spendable outputs.

> **Comments:**
> **username_5**: Limits on transaction sizes suggest that it would be hard to create a transaction this big nowadays. There is a 100K limit on "standard" transactions [See here](https://github.com/bitcoin/bitcoin/blob/master/src/main.h#L57)  

---

### Answer by username_1 on 2021-04-13. Score: 2

**Scripts to find it out yourself + preprocessed data**

I have uploaded scripts that extract most of the data you ask at: <https://github.com/cirosantilli/bitcoin-strings-with-txids> including the top 10k transactions for each category.

Those scripts rely on <https://github.com/alecalve/python-bitcoin-blockchain-parser> which parses the blockchain data offline and without the need for a running local server.

The scripts could quickly update the data at any time efficiently from the last snapshot, and this is what I've found when I last updated on February 2021:

* byte size: list at [`data/tx_size_bytes`](https://github.com/cirosantilli/bitcoin-strings-with-txids/blob/master/data/tx_size_bytes):  [bb41a757f405890fb0f5856228e23b715702d714d59bf2b1feb70d8b2b4e3e08](https://www.blockchain.com/btc/tx/bb41a757f405890fb0f5856228e23b715702d714d59bf2b1feb70d8b2b4e3e08) (Jul 2015) with 999,657 bytes, it regroups a bunch of smaller outputs into one big one. The values are small, so it's likely made for the data and not value.

  This transaction is sometimes dubbed "The Megatransaction", and is mentioned e.g. at:

  + <https://en.bitcoin.it/wiki/July_2015_flood_attack>:

    > The July 2015 flood attack was a large "stress test" of the Bitcoin network. The possibly distributed attack has provoked hundreds of thousands of transactions, leaving over 80,000 in the mempool at one time. The attack is subsequent to stress tests executed in June.
  + [Longest-time-verifying block](https://bitcoin.stackexchange.com/questions/59986/longest-time-verifying-block): unsurprisingly it also took the longest to verify
* number of inputs: [`data/tx_nins`](https://github.com/cirosantilli/bitcoin-strings-with-txids/blob/master/data/tx_nins): [f2e197a6d8d088b13afd0f99d4027da36a9413b9f3d7730ba5278132ebc950a7](https://www.blockchain.com/btc/tx/f2e197a6d8d088b13afd0f99d4027da36a9413b9f3d7730ba5278132ebc950a7) (Aug 2015) + 8 other tied with 20,000
* number of outputs: [`data/tx_nouts`](https://github.com/cirosantilli/bitcoin-strings-with-txids/blob/master/data/tx_nouts): [dd9f6bbf80ab36b722ca95d93268667a3ea6938288e0d4cf0e7d2e28a7a91ab3](https://www.blockchain.com/btc/tx/dd9f6bbf80ab36b722ca95d93268667a3ea6938288e0d4cf0e7d2e28a7a91ab3) (Jan 2016) with 13,107 outputs. Some of them have been spent, so it is not all just data embedding


---

### Answer by username_2 on 2019-01-18. Score: 2

The largest transaction by size to date was the [Mega Transaction](https://blockchair.com/bitcoin/transaction/bb41a757f405890fb0f5856228e23b715702d714d59bf2b1feb70d8b2b4e3e08) mined by f2pool on 7 July 2015:
It was 999,657 bytes, had 5,569 inputs and 1 output.

The transaction filled a complete block by itself and that block was widely cited as taking 25 seconds to validate. The transaction caused a lot of discussion back then, and prompted e.g. this [blog post about the Mega Transaction's validation time by Rusty Russell](https://rusty.ozlabs.org/?p=522).


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### Answer by username_3 on 2018-02-08. Score: 0

i found transactions with 20,000 inputs
[cf1032c2213e6faea04f1813aa6890e7f588bb378cb98e7425aec83c11d4457c](https://blockchain.info/tx/cf1032c2213e6faea04f1813aa6890e7f588bb378cb98e7425aec83c11d4457c)
[30b3b19b4d14fae79b5d55516e93f7399e7eccd87403b8dc048ea4f49130595a](https://blockchain.info/tx/30b3b19b4d14fae79b5d55516e93f7399e7eccd87403b8dc048ea4f49130595a)
[f2e197a6d8d088b13afd0f99d4027da36a9413b9f3d7730ba5278132ebc950a7](https://blockchain.info/tx/f2e197a6d8d088b13afd0f99d4027da36a9413b9f3d7730ba5278132ebc950a7)
[8dabbf51f78c1e7286866af1de403118c5ddbe57ca93b54859245916d2bf1063](https://blockchain.info/tx/8dabbf51f78c1e7286866af1de403118c5ddbe57ca93b54859245916d2bf1063)
[740ac533882221099e7202bbdafbb99ec589c6e74fd2fe7ca1274b46ea4f0a96](https://blockchain.info/tx/740ac533882221099e7202bbdafbb99ec589c6e74fd2fe7ca1274b46ea4f0a96)
[dd6067e71c04cb62f8e5aa52ecc99b01ffcd551a52727d046a2fabb14eb39b4d](https://blockchain.info/tx/dd6067e71c04cb62f8e5aa52ecc99b01ffcd551a52727d046a2fabb14eb39b4d)


---

