Quick Tip: How to increase the console log size in Firefox

Recently I discovered that the console log size in Firefox has a default limit, which prevented me from viewing the full output from a script I was running.

If you find yourself with the same problem, you can change the size of the console log by following these steps.


1) Access the Firefox config file by typing about:config in the browser’s address bar and hitting enter.

2) You will than likely receive a warning message about the risks of changing your browser’s configuration, which you will need to accept before proceeding. Note: Make sure you fully understand the risks of changing any configuration settings before you apply your changes.

3) Search for the preference name devtools.hud.loglimit.console, which should than appear as the only preference in the search results list.

4) Lastly, double click on the preference name and a popup window will allow you to alter the size of the console log from the default value to one you specify.


Screen-shot of changing the console log size in Firefox


2 thoughts on “Quick Tip: How to increase the console log size in Firefox

  1. Doesn’t work. It has a maximum limit you can enter… it will always cut off some of your logs, you have no choice.

    • Hi Joe,

      Thanks for the comment. I just took a look at the about:config and the devtools.hud.loglimit.console preference isn’t listed in the about:config anymore (at least not in Firefox v61). I tried running the following for(var i = 0; i < 11000; i++){console.log(i);} in the console but the log is limited to 10,000 lines.

      I was able to increase the log limit by increasing the devtools.hud.loglimit preference default value from 10,000 to 100,000 and this did allow Firefox to show more than 10,000 lines in the console, however I couldn't find much online about this preference at this time, so I'm not sure if this has a hard limit or what potential side effects this could cause. So update the limit at your own risk.

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