What’s the best format of a hard disk for a clean installation of Mojave’s?

The best format for a clean install is Mac OS X Extended (aka HFS+).

The Mojave installer will automatically convert the drive to APFS if it is an SSD, however by starting off as HFS+ you give it a chance to get started, determine if a firmware upgrade is needed first, install the firmware, and then carry on with the installation of Mojave.

If you try installing on an APFS volume before the firmware has been upgraded the Mac may not have the required firmware support and will fail to boot to the next stage.

Welcome to the Apple Support Communities!

I understand you are going to erase your hard drive and install macOS Mojave on it. The resource below explains the different options for formatting the hard drive based on what was installed on it prior, and what you intend to do with it. macOS Mojave will install on a drive formatted for either macOS Extended Journaled or APFS.
How to erase a disk for Mac
How to upgrade to macOS Mojave​
Take care.

Below I have mentioned a complete process step by steps on how to upgrade your Mac with latest macOS Mojave without facing any data loss problems:-

1.First check your Mac computer system compatibility:-

Being a Mac user, you can easily upgrade to Mojave from Mac OS X Mountain Lion or later on any of the following Mac models. Your Mac should have at-least 2GB of RAM and 15 GB of free available storage space.

2.Make a data backup-most important

Before installing any new Mac operating system,it is always a good practice to take complete Mac backup either using Time machine or any 3rd party tool (depending on your choice).

3.Connect your Mac with proper internet connection and power

Make sure that your Mac computer is connected with proper internet and power connection. Since it takes time to download and install new Mac OS.

4.Finally download macOS Mojave

Now, download macOS Mojave from this Apple link.

5.Start Mac installation

After downloading the OS, the installer will open up automatically. Click Continue and then follow the onscreen instructions.

6.Update

Finally, after the Mojave installation; you will be notified when the new updates are available. A Mac user can also check these updated manually.

HFS+ for rotational drives, and APFS for SSD and internal flash storage.

I have read elsewhere since my previous post that Mojave is in charge, and will format everything as APFS, including Fusion drives, internal HFS+, and external drives that are HFS+.

Hello alex_h1,

I am interested to install macOS Mojave on HFS+ formatted drive. Do you know how can i do it?