Why my Reflection from scene capture cube is always 2~3 times larger than the real world

When I used scene capture cube to get the mirror effect to my StaticMesh in UE4, I found the scale of content in reflection (came frome a HDR picture which generate by scene capture cube and cube render target) ,for example,I put a box in front of the StaticMesh used cube render target map in its emessive,the reflection is 2~3 times larger than the real box. I wonder how can I control the size of the reflection? Thanks~

I also want to know!

Might be a bit of a necro, but it’s probably the size of ur plane.

If u make the plane bigger, the image gets scaled to fit it, bigger plane = bigger picture. Not sure how to fix it though, increasing FOV or increasing distance between the scene capture and the plane it’s projecting to are the first 2 things i can think of.

Maybe something like this: