<p>A transaction is not a fixed size. Removing one large one will have no impact on the count, but removing ten thousand small ones will.</p>

CC BY-SA 4.0
2021-01-05T12:59:57.643Z
Oh! I get it! And large ones are primarily defined by MANY inputs and/or MANY outputs, right? This starts to make sense, thanks! Still kinda strange, that this results in such a huge variation across blocks.
cryptoNoob
CC BY-SA 4.0
2021-01-05T13:31:51.047Z
Additionally, this graph only has a data point every minute, and sometimes more than one block is found in a minute.
Murch
CC BY-SA 4.0
2021-01-05T14:01:33.393Z
Oh, fair point Murch, this better explains HUGE drops
cryptoNoob
CC BY-SA 4.0
2021-01-05T12:57:43.657Z
2021-01-05T12:57:43.657Z
Claris
<p>Not every drop is because of a block. Some are dropped because they have been in the mempool for 14 days and it's time for them to be dropped (this is set using <code>mempoolexpiry</code> in Bitcoin Core)</p>
<p>But yes, this graph shows a large drop because of a block.</p>

CC BY-SA 4.0
2021-01-05T14:05:10.593Z
oh this is also a good point, thanks, interesting
cryptoNoob
CC BY-SA 4.0
2021-01-05T14:03:11.373Z
2021-01-05T14:03:11.373Z
MCCCS
<p>I was just browsing the following mempool visualization and couldn't come up with a good explanation why the drops in unconfirmed transaction count are not of pretty much constant height but vary wildly.</p>
<p>My assumption is that every drop represents a newly mined block. Why are there apparently some blocks which contain very few or almost no transactions while others in contrast contain a relatively large number of transactions?</p>
<p>My only theory that miners are just too stupid to include all the available maximum fee transactions up to the maximum block size they can find seems .. too stupid to be true.</p>
<p>Please explain! Thanks :)</p>
<p><a href="https://i.sstatic.net/rf4N1.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/rf4N1.png" alt="enter image description here" /></a></p>

<transactions><mempool>
Why are the drops in mempool unconfirmed transaction count not of constant height?
cryptoNoob
# Why are the drops in mempool unconfirmed transaction count not of constant height?

(Asked by: username_0 on 2021-01-05)

I was just browsing the following mempool visualization and couldn't come up with a good explanation why the drops in unconfirmed transaction count are not of pretty much constant height but vary wildly.

My assumption is that every drop represents a newly mined block. Why are there apparently some blocks which contain very few or almost no transactions while others in contrast contain a relatively large number of transactions?

My only theory that miners are just too stupid to include all the available maximum fee transactions up to the maximum block size they can find seems .. too stupid to be true.

Please explain! Thanks :)

[![enter image description here](https://i.sstatic.net/rf4N1.png)](https://i.sstatic.net/rf4N1.png)

**Tags:** transactions, mempool


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## 2 answers

### Answer by username_1 on 2021-01-05. Score: 1 | Accepted answer

A transaction is not a fixed size. Removing one large one will have no impact on the count, but removing ten thousand small ones will.

> **Comments:**
> **username_0**: Oh! I get it! And large ones are primarily defined by MANY inputs and/or MANY outputs, right? This starts to make sense, thanks! Still kinda strange, that this results in such a huge variation across blocks.  
> **username_2**: Additionally, this graph only has a data point every minute, and sometimes more than one block is found in a minute.  
> **username_0**: Oh, fair point username_2, this better explains HUGE drops  

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### Answer by username_3 on 2021-01-05. Score: 0

Not every drop is because of a block. Some are dropped because they have been in the mempool for 14 days and it's time for them to be dropped (this is set using `mempoolexpiry` in Bitcoin Core)

But yes, this graph shows a large drop because of a block.

> **Comments:**
> **username_0**: oh this is also a good point, thanks, interesting  

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