QGIS runs on multiple platforms: Windows, Mac OS, Linux, Unix and Android. To install QGIS, you need to download the installer for your operating system from the QGIS website. The installer includes QGIS and a number of associated packages and libraries. To see what libraries and packages are installed with your version of QGIS, please check the terms of license prompt before you install. You can save a copy of the terms of license as well. You should download the latest release or the long term release based on personal preference; the latest release has more rich features, but the long term release is the most stable.

For Windows, you will have the option of using the OSGeo4W network installer or downloading the QGIS standalone installer. Most versions of Windows are 64-bit, so it is recommended to install the 64-bit installer. You can check your version of Windows by typing "system information" in the Windows search box and clicking on the system information icon or by opening File Explorer and right-clicking on This PC > Properties. Under System Type, you will see the version of Windows.
 

Using the OSGeo4W Network Installer

OSGeo4W is a binary distribution of open source GIS software. Using the OSGeo4W Network Installer allows you to install either the binary or source code version of QGIS along with other open source tools and their dependencies.  Using this is recommended if you want to install older versions of QGIS on Windows 8 or 10.

 

Using the Desktop Express Install

If you want to install the latest release of QGIS, then choose Desktop Express Install. 

You will then be prompted to choose a download site. Choose any site based on your preference.

 

 

At the next window, keep everything checked. You will want to install QGIS, GDAL, and GRASS GIS. After that, QGIS will begin to download. You will be prompted to agree with the terms of Non-Open Source License Agreements several times for the packages you are installing. Read the license agreement and click "I agreed with above license terms".

 

Click Next. QGIS and related packages will begin to download. it might take some time to install QGIS and its associated packages this way.

 

You will get a prompt that installation was successful after installation is completed.

 

Using the QGIS Standalone Installer

Note: These installation instructions are for QGIS 3.12. Some of the prompts you see might be different for later versions.

1. In your Downloads folder, click on the QGIS Installer. You will be prompted if you want to allow this app to make changes to your device. Click Yes.

2. This will prompt the Setup Wizard. Click Next.

3. Read the License Agreement and if you agree, click I Agree.

 

4. Choose an Install location. It is recommended that you keep the default location.

 

 

5. Choose the components you want to install and click Install. This might take a while.

 

 

6. Chose whether you want to reboot now or manually reboot later and then click Finish.

 

For Mac, you will need to download the QGIS macOS Installer then click on the installer in Downloads folder on your dock. The filename should be qgis-macos-pr.dmg or something similar. You will be prompted to move QGIS to your Applications folder.

 

 

Drag the QGIS icon to your Applications folder and QGIS will be copied to the Applications folder. Click on QGIS either from the Launchpad or go to Finder > Applications. You might not be able to start QGIS due to security reasons and might get this message:

 

 

 

 

Please refer to this article on how to safely open apps on your Mac.