There is no honest single answer to how many websites on one VPS. The number of sites is a poor measure. A site with no visitors uses almost nothing, and one busy shop can use more memory than many brochure sites. What counts is how many requests run at the same moment, how much memory each request needs, and how much the database keeps in memory.
This page gives a method for the question how much RAM does a VPS need: list the memory consumers, put a number on each by measuring, add them up, and leave headroom. It also maps common site types to the factors that drive RAM and CPU, and shows which of our plans answers which question.
What the vendors actually say about requirements
Official requirement pages are less specific than many hosting guides suggest. They are still the right starting point.
- WordPress: the WordPress.org requirements page recommends PHP 8.3 or newer, MariaDB 10.11 or newer or MySQL 8.0 or newer, Apache or Nginx, and HTTPS support. It states no minimum for RAM or disk.
- WooCommerce: the WooCommerce server recommendations ask for PHP 8.3 or newer, a PHP
memory_limitof 256 MB or higher for WordPress, and MySQL 8.0 or newer or MariaDB 10.6 or newer. Thememory_limitis a ceiling per request, not a typical figure. - Ubuntu Server: the Ubuntu documentation lists, for 24.04 on amd64, a minimum of 1.5 GB RAM for an ISO install (1 GB for cloud images) and suggests at least 3 GB RAM and 25 GB of storage. This describes the operating system alone, before any website runs.
- MySQL: the MySQL manual says the default configuration is designed to start on a virtual machine with about 512 MB of RAM, and that you can raise or lower buffers to fit the machine.
From these sources you can conclude only two things: the operating system needs a base amount, and the application sets a ceiling per request. The rest depends on your sites.
A method to size a VPS for several websites
Step 1. Measure memory per PHP worker
PHP-FPM runs PHP in worker processes. The PHP manual describes three process modes. In static mode the number of workers is fixed. In dynamic mode it moves between spare-server limits. In ondemand mode workers start when requests arrive and stop after an idle timeout. In all modes pm.max_children is the upper limit and also the limit of simultaneous requests served; extra requests have to wait, which is our reading of the limit.
The manual gives no formula for memory. It does offer a way to measure: the access.format setting can log the peak memory a request used. Log it under real traffic and take a typical and a high value for each site. Heavy plugins and large imports raise it.
Step 2. Size the database
The InnoDB buffer pool caches table and index data in memory. The MySQL manual says it can be sized by innodb_buffer_pool_size and recommends 50 to 75 percent of system memory in its discussion of memory use. It also warns that a pool that is too large causes swapping. The MariaDB documentation says the goal is to hold most of the active data, and gives a check: after warm-up, reads from disk should stay below about 1 percent of read requests.
A server that also runs PHP workers cannot give the database that share, so the buffer pool must be smaller. The MySQL manual also lists per-connection buffers, such as the sort buffer, that add memory for each active connection.
Step 3. Add the operating system and other services
Add the base needs of the operating system, the web server, security software and any cache. Take these from measurements on your own machine and not from a table.
Step 4. Leave headroom and test
Do not plan for 100 percent use. The operating system uses spare memory to cache files, which makes sites faster, and a traffic spike needs room. If the server starts to swap, the sizing is too tight. Test with realistic traffic before you move clients.
Worked example: illustrative arithmetic, not a benchmark
The numbers below are assumptions chosen to show the method. They are not measurements of any real site or server. Replace each with a value you measured.
| Item | Assumed value | How it was derived |
|---|---|---|
| Server RAM | 8,192 MB | An 8 GB server. |
| Operating system and services | 1,024 MB | Assumption. Measure your own. |
| Database buffer pool plus connections | 2,560 MB | Assumption: about 2,048 MB for the buffer pool and 512 MB for connections. |
| Headroom for file cache and spikes | 1,600 MB | Assumption: about 20 percent of RAM. |
| Left for PHP workers | 3,008 MB | 8,192 - 1,024 - 2,560 - 1,600. |
| Memory per PHP worker | 80 MB | Assumption: the peak memory you would log with access.format. |
| Maximum PHP workers | 37 | 3,008 / 80 = 37.6, rounded down. |
In this example the server can hold at most 37 PHP requests in progress at once, shared by all sites. It says nothing about how many sites that is. If each request takes a fraction of a second, a small number of workers can serve many visitors. If requests are slow, the same workers fill up quickly. CPU is a second limit: only as many workers as there are vCPUs can compute at the same moment.
With ondemand pools, idle sites do not hold workers, which is why a server with many quiet sites can use little memory. With static pools every site keeps its workers, and memory use grows with the number of sites. Which mode fits depends on your traffic pattern.
Site types and the factors that drive RAM and CPU
| Site type | What drives RAM | What drives CPU | What to measure | Sourced requirement |
|---|---|---|---|---|
| Brochure site (static or light PHP) | Few workers; small database or none | Low unless traffic is high or images are processed | Requests per second, peak worker memory | None stated |
| WordPress with plugins | Memory per PHP request grows with plugins and page builders; database size | PHP execution on uncached pages, search, admin use | Peak memory per request, cache hit rate, slow queries | PHP 8.3 or newer; MariaDB 10.11 or newer or MySQL 8.0 or newer; no RAM minimum stated |
| WooCommerce shop | Higher per-request memory; larger database; carts and checkout are not cacheable in the same way as pages | Checkout, search, order processing, scheduled jobs | Peak memory on checkout, database buffer pool hit rate | PHP memory_limit of 256 MB or higher; PHP 8.3 or newer |
| Node.js app | Heap size of each process; number of processes; in-memory caches | Event loop load and CPU-heavy code | process.memoryUsage() over time, heap limit | Heap limit is based on system memory; measure before tuning |
The columns on drivers and measurements are our own reasoning from the documents named in this page. Only the last column is a direct statement of a source. The Node.js statement is from the Node.js documentation on memory.
Page caching often has a large effect on content sites, because a cached page does not start PHP or query the database. Logged-in users, carts and checkouts often bypass the cache. This is why a shop and a blog of the same size need different servers.
How much RAM does a VPS need? Start from the workload
Use the arithmetic above to find a starting size, then check it against reality in the first weeks. Warning signs that RAM is too low are swap use, workers that are killed or restarted, and a database that reads from disk all the time. Warning signs that CPU is too low are request queues and slow responses while memory is free.
Real capacity depends on traffic, caching and code. Two WordPress sites with the same visitors can differ widely in memory use because of their plugins. Measure your own sites, do not rely on a number from a blog post, including this one.
PFHW plans and the question each answers
All PFHW plans include the control panel with no limit on sites or accounts. The limit is the resources of the server. vCPU and RAM are dedicated, not shared. Prices are in euros per month excluding VAT, billed monthly with no contract.
| Plan | Price per month | vCPU | RAM | Storage | Question it answers |
|---|---|---|---|---|---|
| Starter | €29 | 2 | 4 GB | 50 GB | Is a small set of light sites enough for a first server? |
| Business | €39 | 4 | 8 GB | 80 GB | Do I need more workers and a larger database cache for several WordPress sites? |
| Pro | €59 | 6 | 12 GB | 120 GB | Do I need more CPU for uncached traffic or a first WooCommerce shop? |
| Enterprise | €69 | 8 | 16 GB | 150 GB | Do I need room for many active sites or a busy shop plus a Node.js app? |
| Corporate | €89 | 12 | 24 GB | 200 GB | Do I need a large database cache and many concurrent workers? |
| Max | €99 | 16 | 32 GB | 250 GB | Do I need the most CPU, RAM and storage we offer on one server? |
Source for plan data: cloudacropolis.com/managed-web-server, read on 7 November 2026. Storage is NVMe or SSD on Ceph with three synchronous copies on separate drives. The right-hand column states a question to ask, not a promise about a number of sites. We do not publish a sites-per-plan figure, because it would depend on your sites.
You can start on a smaller plan and see how your sites behave. The managed service includes system metric monitoring, which helps you see memory and CPU use over time. Request a demo and then a trial server to measure your own sites before you decide.
Where PFHW fits, and where it does not
Where it fits
- You host many small and medium sites and want one server with dedicated vCPU and RAM and no per-site limit.
- You want engineers to handle operating system patches, the firewall, network edge configuration and backup administration, while you keep control of the sites.
- You want to test with your real sites on a trial server before you commit.
- You need the data in the EU: Tier III data centre in Vilnius, Lithuania.
Where it does not, or where you should check first
- We cannot tell you a number of sites per plan without measuring your sites.
- The top plan has 16 vCPU and 32 GB RAM. Workloads that need more than one server need a different design; talk to us.
- Email is a separate add-on on its own server and does not use the web server's RAM.
- There is no automatic certificate issuing: certificates are uploaded or bought from us.
- The panel interface is English only at present.
Frequently asked questions
How many websites can I host on one VPS?
It depends on traffic, caching and code, not on a fixed number. Many quiet sites can fit on a small server, while one busy shop can fill a large one. Size by concurrent requests and memory per request, then measure.
How much RAM does a VPS need for WordPress?
The WordPress.org requirements page states no RAM minimum. Add the operating system, the database cache, PHP workers and headroom, using values you measured. WooCommerce recommends a PHP memory limit of 256 MB or higher.
Is 4 GB of RAM enough?
It can be for a few light sites with page caching. It is tight for a shop or many plugin-heavy sites. The Ubuntu documentation suggests at least 3 GB RAM for the operating system alone, so 4 GB leaves little room if you also run a database.
How do I measure memory per PHP worker?
Set the PHP-FPM access.format option to log peak memory per request, as described in the PHP manual, and read the values under real traffic. Use a high value, not the average, when you set the worker limit.
Does adding more vCPUs fix a slow site?
Only if CPU is the bottleneck. Slow queries, missing caching and too few workers are common causes that more vCPUs do not fix. Check where time is spent first.
Is there a limit on sites in PFHW?
No. All PFHW plans include the control panel with no limit on sites or accounts. The practical limit is the CPU, RAM and storage of your server.
Related resources
- Managed web hosting vs shared hosting vs unmanaged VPS
- WordPress Redis object cache
- Node.js and Python hosting
- Agency hosting for multiple clients
- Managed VPS hosting comparison
Sources
- WordPress requirements, WordPress.org
- WooCommerce server recommendations, WooCommerce
- FastCGI Process Manager configuration, PHP manual
- How MySQL uses memory, MySQL 8.0 Reference Manual
- InnoDB buffer pool, MariaDB documentation
- System requirements, Ubuntu Server documentation
- Understanding and tuning memory, Node.js documentation
- Managed Web Server, CloudAcropolis