@AlexMachin1997 said:

It would be great to get something like "w250_and_h141_bestv2" but for "posters", I've already tried this for mobile but you can't see all the content.

This is not possible for posters, as the width of a poster is smaller that its height. Typicallyn the height is 1.5 x the width.

@AlexMachin1997 said:
Movie or TV image sizes
Hi everyone,
I'm in the process of trying to find some suitable image sizes but I'm having difficulty. So far this is the sizes I'm using:
Backdrops:

• "w533_and_h300_bestv2" for desktop
• "w250_and_h141_bestv2" for mobile

Posters:

• "w220_and_h330_bestv2" for desktop
• "w94_and_h141_face" for mobile

The problem I'm having is trying to get the right sizes for the "posters" on mobile,
is there a list of possible sizes for posters which have both the height and width specified ?

There are some undocumented measurements that are used in the TMDb WEB interface.
These may at any time be discontinued if there is a change in the layout of the website.
Perhaps some you are using are from this group.

The official list of sizes can be found here.
https://api.themoviedb.org/3/configuration?api_key=THE_KEY

A chart of official image sizes.

Image Size

See here
https://developers.themoviedb.org/3/configuration/get-api-configuration

Download Supported Image Sizes (For use with HTML, App, programming etc ...)

|  poster  | backdrop |  still   | profile  |   logo   |
| :------: | :------: | :------: | :------: | :------: |
| -------- | -------- | -------- |    w45   |    w45   |
|    w92   | -------- |    w92   | -------- |    w92   |
|   w154   | -------- | -------- | -------- |   w154   |
|   w185   | -------- |   w185   |   w185   |   w185   |
| -------- |   w300   |   w300   | -------- |   w300   |
|   w342   | -------- | -------- | -------- | -------- |
| -------- | -------- | -------- |   h632   | -------- |
|   w500   | -------- | -------- | -------- |   w500   |
|   w780   |   w780   | -------- | -------- | -------- |
| -------- |  w1280   | -------- | -------- | -------- |
| original | original | original | original | original |  

Original Size is the size of the uploaded image.
It can be between Min Res (Minimum Resolution) and Max Res (Maximum Resolution).
See these values below.

Upload Supported Image Sizes (in pixels)

| API name |      Item       |   Min Res  |   Max Res   | Aspect Ratio |  
| :------: | :-------------: | :--------: | :---------: | :----------: |  
|  poster  |     Poster      |  500 x 750 | 2000 x 3000 |   1 x 1.5    |  
| backdrop |     Fanart      | 1280 x 720 | 3840 x 2160 | 16 x 9 (1.77)|  
|   still  | TV Show Episode | 1280 x 720 | 3840 x 2160 | 16 x 9 (1.77)|  
|  profile |    Cast/Crew    |  300 x 450 | 2000 x 3000 |   1 x 1.5    |