How to calculate RAM allocation for a web server?

Question

ubuntu

Given: VPS with 4GB of RAM (you can take 8). Ubuntu 18.04, PHP7.3, MariaDB, a Wordpress/Woocommerce store where you have to keep quite a few plugins. nginx + php fpm

How much RAM to give PHP? How Much Muscle? You can also set the constant and peak size of the RAM for WordPress itself - how much to allocate?

The base of the store is small, about 85 megs, but there are quite a lot of requests, in the admin panel it can reach up to 700-800. The maximum load usually falls on PHP.

Answer 1

And what are you going to share?
All that is needed will divide the memory itself

Answer 2

The more memory, the better. The web server - by the residual principle, PHP - to have enough to execute all the scripts with the estimated attendance.

Answer 3

If the base is small, then a lot of memory is not needed.
I think 1gb is enough for a VPS, 300mg is enough for a database, 500mg is enough for growth.
The bottleneck can be in the number of cores. You need at least 2, preferably 4.
300 is also enough for cache php.
PS. The main thing IMHO here is not megabytes, but the setting.
Change, test, draw conclusions. Test platforms in bulk, ranging from ab (apache2utils) to yandex tank.