<p>'minRelayTxFee' is the node's minimum reward (BTC/KB) for a transaction "transmission" (relay). In the p2p network there could be a node (A) with a
minRelayTxFee setted at 0,0001 and a node (B) with a minRelayTxFee setted at 0,0003. In the case of a transaction of 2 KB with a fee of 0,0002 , 
this tx will be included in the A's mempool and not in the B's mempool.</p>

CC BY-SA 3.0
2016-08-24T15:51:12.790Z
2016-08-24T15:51:12.790Z
Antony Zappacosta
<p>The <code>minRelayTxFee</code> specifies a feerate acting as a lower bound for a node's mempool. A node will not admit unconfirmed transactions below that feerate to its mempool and thus will not relay them to its peers. The <code>minRelayTxFee</code> is a configuration setting and can be specified by each node operator independently. The value only impacts unconfirmed transactions, transactions included in a block are processed even when they do not meet the <code>minRelayTxFee</code>. Note that contrary to its name's implication, the <code>minRelayTxFee</code> is not an absolute fee, but a feerate.</p>
<p>The current default value for the <code>minRelayTxFee</code> in <a href="https://github.com/bitcoin/bitcoin/blob/97153a702600430bdaf6af4f6f4eb8593e32819f/src/validation.h#L63" rel="noreferrer">Bitcoin Core</a> is 1000 satoshi/kB (= 1 sat/B). A node operator may specify a different value via the startup parameter <code>-minrelaytxfee=&lt;amt&gt;</code> or the configuration parameter <code>minrelaytxfee=&lt;amt&gt;</code> which takes an <code>&lt;amt&gt;</code> in [BTC/kB].</p>
<p>The <code>minRelayTxFee</code> also serves as the basis to calculate the minimum cost increments for replacement transactions per BIP-125 (Opt-in RBF). It was also previously used to calculate the <a href="https://bitcoin.stackexchange.com/q/10986/5406">dust limit</a> which has since been decoupled into a separate feerate called <a href="https://github.com/bitcoin/bitcoin/blob/0.19/src/policy/policy.h#L50" rel="noreferrer"><code>DUST_RELAY_TX_FEE</code></a> with a default value of 3000 sat/kvB (H/T <a href="https://bitcoin.stackexchange.com/users/100290/darius">Darius</a>).</p>
<p><code>minRelayTxFee</code> should not be confused with:</p>
<ul>
<li><code>minTxFee</code>, which is a wallet configuration setting that sets a lower bound when creating new transactions</li>
<li><code>mempoolminfee</code>, which is an independent lower bound for mempool acceptance that dynamically increases when the <a href="https://bitcoin.stackexchange.com/a/96070/5406">mempool limit is exceeded</a></li>
</ul>
<p><a href="https://bitcoin.org/en/release/v0.13.0" rel="noreferrer"><code>Bitcoin Core 0.13.0</code></a> introduced a new, optional <code>feefilter</code> P2P message, which will tell neighboring nodes not to send transactions below the filter's feerate. Older nodes do not communicate their minimum feerate, but rather just drop incoming transactions that doesn't pass it.</p>
<p>You may retrieve the current values for your node by calling the <a href="https://bitcoincore.org/en/doc/0.19.0/rpc/blockchain/getmempoolinfo/" rel="noreferrer"><code>getmempoolinfo</code></a> RPC.</p>

CC BY-SA 4.0
2021-04-08T20:10:34.267Z
What's the default value of `feefilter`? I searched the code but didn't find an obvious constant. Also didn't see it mentioned in the BIP. ty
Donn Lee
CC BY-SA 4.0
2021-04-08T21:30:07.080Z
@DonnLee: It's a protocol message between peers setting a lower bound on the feerate for transaction forwarding: https://en.bitcoin.it/wiki/Protocol_documentation#feefilter
Murch
CC BY-SA 4.0
2016-08-24T20:40:13.537Z
2021-07-20T18:49:25.637Z
2021-07-20T18:49:25.637Z
Murch
<p>What is the <code>minRelayTxFee</code>?<br>
What is it used for, what's the default value and how does the value change?</p>

<transaction-fees><terminology><mempool>
What is the minRelayTxFee?
Murch
# What is the minRelayTxFee?

(Asked by: username_0 on 2016-08-24)

What is the `minRelayTxFee`?  
What is it used for, what's the default value and how does the value change?

**Tags:** transaction-fees, terminology, mempool


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## 2 answers

### Answer by username_0 on 2016-08-24. Score: 21 | Accepted answer

The `minRelayTxFee` specifies a feerate acting as a lower bound for a node's mempool. A node will not admit unconfirmed transactions below that feerate to its mempool and thus will not relay them to its peers. The `minRelayTxFee` is a configuration setting and can be specified by each node operator independently. The value only impacts unconfirmed transactions, transactions included in a block are processed even when they do not meet the `minRelayTxFee`. Note that contrary to its name's implication, the `minRelayTxFee` is not an absolute fee, but a feerate.

The current default value for the `minRelayTxFee` in [Bitcoin Core](https://github.com/bitcoin/bitcoin/blob/97153a702600430bdaf6af4f6f4eb8593e32819f/src/validation.h#L63) is 1000 satoshi/kB (= 1 sat/B). A node operator may specify a different value via the startup parameter `-minrelaytxfee=<amt>` or the configuration parameter `minrelaytxfee=<amt>` which takes an `<amt>` in [BTC/kB].

The `minRelayTxFee` also serves as the basis to calculate the minimum cost increments for replacement transactions per BIP-125 (Opt-in RBF). It was also previously used to calculate the [dust limit](https://bitcoin.stackexchange.com/q/10986/5406) which has since been decoupled into a separate feerate called [`DUST_RELAY_TX_FEE`](https://github.com/bitcoin/bitcoin/blob/0.19/src/policy/policy.h#L50) with a default value of 3000 sat/kvB (H/T [Darius](https://bitcoin.stackexchange.com/users/100290/darius)).

`minRelayTxFee` should not be confused with:

* `minTxFee`, which is a wallet configuration setting that sets a lower bound when creating new transactions
* `mempoolminfee`, which is an independent lower bound for mempool acceptance that dynamically increases when the [mempool limit is exceeded](https://bitcoin.stackexchange.com/a/96070/5406)

[`Bitcoin Core 0.13.0`](https://bitcoin.org/en/release/v0.13.0) introduced a new, optional `feefilter` P2P message, which will tell neighboring nodes not to send transactions below the filter's feerate. Older nodes do not communicate their minimum feerate, but rather just drop incoming transactions that doesn't pass it.

You may retrieve the current values for your node by calling the [`getmempoolinfo`](https://bitcoincore.org/en/doc/0.19.0/rpc/blockchain/getmempoolinfo/) RPC.

> **Comments:**
> **username_2**: What's the default value of `feefilter`? I searched the code but didn't find an obvious constant. Also didn't see it mentioned in the BIP. ty  
> **username_0**: @username_2: It's a protocol message between peers setting a lower bound on the feerate for transaction forwarding: https://en.bitcoin.it/wiki/Protocol_documentation#feefilter  

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### Answer by username_1 on 2016-08-24. Score: 7

'minRelayTxFee' is the node's minimum reward (BTC/KB) for a transaction "transmission" (relay). In the p2p network there could be a node (A) with a
minRelayTxFee setted at 0,0001 and a node (B) with a minRelayTxFee setted at 0,0003. In the case of a transaction of 2 KB with a fee of 0,0002 ,
this tx will be included in the A's mempool and not in the B's mempool.


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