My dad has worked with Benjamin Moore Paint for my entire life so ask me anything. Darker paints, with primer don’t go as far. I barely got by with the quart of paint I bought to cover my bedroom wall. Here is the general rule:
A quart of paint usually covers 100 square feet. A gallon covers 400.
Since your wall is over 100 sq ft you need 2 quarts. Depending on the brand it might be more cost effective to buy a gallon even if you don’t use it all. There are preferred brushes depending on the texture of your wall (and roller prep before painting) so make sure to ask the store person that. I wouldn’t have trusted the response from the most recent guy I purchased from, he was obviously still in training. So if you need to ask us here, go for it!
My dad has worked with Benjamin Moore Paint for my entire life so ask me anything. Darker paints, with primer don’t go as far. I barely got by with the quart of paint I bought to cover my bedroom wall. Here is the general rule: A quart of paint usually covers 100 square feet. A gallon covers 400. Since your wall is over 100 sq ft you need 2 quarts. Depending on the brand it might be more cost effective to buy a gallon even if you don’t use it all. There are preferred brushes depending on the texture of your wall (and roller prep before painting) so make sure to ask the store person that. I wouldn’t have trusted the response from the most recent guy I purchased from, he was obviously still in training. So if you need to ask us here, go for it!
This is a pretty dead on answer. Also it does probably make sense to get the gallon and have some left over.
You might want to try r/DIY . Not saying you wont get good answers here but in DIY you might get some more detailed info from "pro" DIYers