cPanel & WHM System Requirements for a VPS

Before you order a server for cPanel & WHM, check that it meets cPanel's requirements. A server that is too small installs fine and then struggles as soon as mail scanning and backups start. This guide explains each requirement in plain terms and how to pick a sensible VPS size.

Note: You install cPanel on your own Linux VPS and buy the licence from cPanel or a partner. Licence prices and tiers change, so check cPanel's website for current terms.

Before you start

Decide roughly how many cPanel accounts and websites you will host, and whether you will run email on the server.
Have cPanel's official system requirements page open. The figures below match cPanel's documentation at the time of writing, but cPanel updates them with new releases.

Supported operating systems

cPanel & WHM supports a short list of 64-bit Linux distributions. At the time of writing, cPanel's documentation lists:

AlmaLinux 8, 9 and 10. AlmaLinux 10 needs cPanel version 132 or later, and AlmaLinux 9 needs 114 or later.
Rocky Linux and CloudLinux releases, each with its own requirements page.
Ubuntu 24.04 LTS. cPanel supports Ubuntu LTS releases in step with its own LTS versions and retires older ones.

Some points that catch people out:

ARM is not supported. The server must be x86_64.
Debian is not supported, and neither are non-LTS Ubuntu releases.
On Ubuntu, the only nameserver option is PowerDNS.

Tip: For a new server, choose the newest OS on cPanel's list that your software supports. It gives you the longest time before an OS upgrade.

Hardware: RAM, disk and CPU

cPanel's published figures for AlmaLinux and Ubuntu are:

CPU: 1.1 GHz minimum (2 GHz recommended on Ubuntu).
RAM: 2 GB minimum, 4 GB recommended, and at least 3 GB if you plan to use ClamAV virus scanning.
Disk: 20 GB minimum, 40 GB recommended. Installs and updates need at least 5 GB free in /usr/local/cpanel.
Inodes: on a single-partition server, at least 1,000,000 inodes, plus 50,000 for every cPanel account you plan.

These are the levels at which cPanel will install. They are not the levels at which a busy server runs well.

Clean install, static IP and hostname

A freshly installed OS

cPanel must go on a fresh operating system. Do not install a web server, database or mail server first, because the installer sets up its own versions. There is no uninstaller, so removing cPanel means reinstalling the OS.

A static public IP

The server needs a static IPv4 address. Addresses handed out by DHCP are not allowed, and IPv6-only servers are not supported. A VPS has a static public IP shown in your VPS provider's control panel.

An FQDN hostname

The hostname must:

be a fully qualified domain name, such as server.example.com;
resolve to the server's IP;
be 60 characters or fewer;
differ from every website domain on the server.

Firewall and SELinux

cPanel recommends turning off the OS firewall (firewalld or UFW) before installing, then adding a cPanel-aware firewall such as CSF. On AlmaLinux and Rocky Linux, SELinux must be disabled.

How to size a VPS for cPanel

Use these as starting points, not promises. Load depends on traffic, PHP code and mail volume.

Personal or test server (a few sites, little mail): 2 vCPU, 4 GB RAM, 60 GB or more of disk.
Small agency or reseller (10–30 sites, email on the server): 4 vCPU, 8 GB RAM, 120 GB or more of disk.
Larger hosting (50 or more accounts, spam and virus scanning): 6–8 vCPU, 16 GB RAM or more, with disk sized at about twice the current site data to leave room for backups.

Things that raise the requirement:

Email. SpamAssassin and ClamAV use a lot of memory per message.
Local backups. Each backup can need as much space as the accounts themselves.
WordPress with heavy plugins. More PHP-FPM workers need more RAM.

Tip: Start one size up from where you think you need to be. Moving accounts to a larger server later is much more work than resizing early.

Check it works

After you order and before you install, confirm the server matches:

Bash

cat /etc/os-release
uname -m
nproc
free -h
df -h /
df -i /
hostname -f

Look for a supported OS name, x86_64, the expected CPU and RAM, at least the planned disk space and inode count, and an FQDN for the hostname.

Troubleshooting

Installer says the OS is unsupported: the release is not on cPanel's current list. Reinstall with a supported one.
Installer stops on low disk space: /usr/local/cpanel needs at least 5 GB free during install and updates. Choose a bigger disk.
Server slows down once email starts: spam and virus scanning use RAM. Add memory or move mail to a dedicated provider.
Hostname rejected: it is the same as a website domain or does not resolve. Use a subdomain like server.example.com with its own A record.

Next steps

Install on the RHEL family: install cPanel & WHM on AlmaLinux.
Install on Ubuntu: install cPanel & WHM on Ubuntu 24.04.
Weighing up options first: cPanel vs Plesk.

Was this guide helpful?

Still stuck?

Ask MdmHost AI for a quick answer, or open a ticket and our team will take a look. We are here 24/7.

Ask MdmHost AI Open a ticket