For every transaction you send in MetaMask, you'll need to pay gas. For a general explainer, see here.

You can easily customize the gas you pay for each transaction according to your circumstances. For example, sometimes you may want to pay more to help your transaction be processed sooner; other times, you may be happy to wait. 

First, let's define the various terms you'll encounter when customizing gas settings:

The gas limit
The gas limit is the maximum amount of gas units you are willing to pay for in order to carry out a transaction or EVM operation.
The max priority fee
The max priority fee goes to the validator, and incentivizes them to prioritize your transaction.
The max fee
The max fee is the total, global amount paid for your transaction: base fee + priority fee.

For PC version: 

 When you start to send a transaction, you'll see an icon above your gas details. This will likely read 'Low', 'Market, or 'Aggressive' depending on the last setting you used:  

 MetaMask Advanced gas market 

Clicking on this button will allow you to choose between these three options. These describe the amount of gas you're choosing to pay, and have these main implications:

  • 'Low' involves paying less for gas, and most likely waiting longer for your transaction to complete.
  • 'Market' sets your gas to reflect the current market rates.
  • 'Aggressive' enables you to be more forceful with your transaction, and have it completed as soon as possible by paying more.

 MetaMask edit gas fee 

Hit 'Advanced' to customize gas parameters directly.

Saving your gas settings for reuse 

The advanced gas fee settings are network-specific, so you can enjoy a personalized and optimized experience for each network you use.

If you want to reuse the settings you've just configured, make sure to check the box that lets you save your settings as the default. Then, simply click 'Save' to ensure your gas settings become the default values for future use.

 MetaMask advanced gas controls save settings

For Mobile:

 When you get to the final screen before sending your transaction, you will see an "Estimated gas fee". To the right, the fee will appear underlined in blue: 
 MetaMask advanced gas controls mobile 

Click on the fee, and a menu will appear with a slider, and another option to click on 'Advanced Options'. The slider lets you pick between three options that describe how much gas you want to pay:

  • 'Low' involves paying less for gas, and most likely waiting longer for your transaction to complete.
  • 'Market' sets your gas to reflect the current market rates.
  • 'Aggressive' enables you to be more forceful with your transaction, and have it completed as soon as possible by paying more.

When you do, this menu will open and you will have the opportunity to customize your gas fully:

 MetaMask advanced gas controls mobile