There are many different techniques that can be used to effectively block Facebook. You can pick one of the techniques detailed below or combine them together for a more robust approach. 

Block Facebook using a DNS Filter

A DNS Filter is one of the best ways to block content of any type for a device. It can be configured on an individual device or enforced an entire network. Tech Lockdown offers a very simple interface for adding sites and domains to block, in addition to categories of content to restrict.

Adding a website to the Blocklist prevents all configured devices to refuse a connection to the website. This can also work for mobile applications (like Facebook's App). 

In addition to blocking Facebook specifically, you can also block the entire Social Media Category, in addition to many other categories of content.

Block Facebook on a Smartphone

Facebook is most prevalent on a Smartphone, simply because it is the best way to share content with other people. It also allows a person to easily stay "online" and connected at all times, which can lead to an unhealthy obsession with the App. 

Block Facebook on an iPhone

iPhone provides a few built-in options to limit what kinds of apps and websites can be visited and does this through the Screen Time option in Settings. To change Screen Time settings for Facebook:

OpenSettings, and Navigate to the Screen Time option. If necessary, search for "Screen Time". Open the App Limitsoption.

UnderApp Limits, tab Add Limit.

Select the Facebook app, and set the allowed time to the lowest possible value.

Under Screen Time, go to Content & Privacy Restrictions, Content Restrictions, and then Web Content.

Under Web Content, you can either choose the option for:

• Limit Adult Websites, and under Never Allow, add Facebook.com.
• Allowed Websites Only, and make sure that Facebook.com is not added to the Allowed Only These Websites list.

Screen Time offers a decent amount of control over moderating what kind of content an iPhone can access, however, there are more advanced approaches. One of the best options is to create a  "Healthy" or "Dumb iPhone  . This allows a device to be very highly controlled, and as a result, become a lot safer.

Block Facebook on an Android

Android offers a few built-in  parental control options   for restricting their devices. Limiting an App is possible without any extra setup; however, the more advanced option is to use Family Link. Family Link allows you to limit what websites can be accessed, whether new apps can installed, and more.

To set up App Timers, find the setting for Digital Wellbeing and parental controls. 

Here, you are able to add an App limit for Facebook and set it to the lowest possible value. 

In order to do more advanced things, like block the Facebook.com website, you will have to use a third-party app, like Google's Family Link.

Another option is to set up a  "Healthy" or "Dumb Android"  . This allows you to set up much more advanced controls and protections on an Android device.

Blocking Facebook on a Computer

There are two main techniques for blocking Facebook on a computer: the Host File and a Blocking Application.

Block Facebook on a Computer using the Hosts file

One method is to use the Hosts File . The Host File is a file on a computer that can be used to change how the computer interacts online. 

Using the Host File method, add these entries:

0.0.0.0 facebook.com
0.0.0.0 fbcdn.net
0.0.0.0 facebook.net

The Host File is one of the most effective ways to block a website on a device, because it allows you to fully cut off a domain name.

Block Facebook on a Computer using a Blocking Application

Using a Blocking application is an effective approach, and usually more user friendly. However, the instructions might change depending on the application being used. The examples below use Cold Turkey , which is a very effective option that can lock out different websites. There is a paid version of Cold Turkey, but the free version can block websites.

Either create a new block or open an existing block

Add the following entries to your Block:

facebook.com
facebook.com/*
fbcdn.net/*

Lock you Block. You can choose to block it until unlocked again (using a password), or for specific times of the day (like evening or work hours) 

Closing Thoughts

Facebook can a great way to connect with family and friends, however, it may also become a huge time-eater. Sometimes, the best thing to do is just block it entirely. 

The most effective way to block content online is to use a Network Filtering Service. DNS Filter is a great option for filtering different categories of content, such as adult content, malware, social media and entertainment, and much more.  Tech Lockdown  offers DNS filtering, premium guides, and professional support for locking down all kinds of devices.