Internal storage still 10806 mb after wipe/format

Hello,

I have wipe my internal storage because after installing custom rom i only have for about 2 GB free internal storage....
But after I wipe it, in TWRP there's only 10806 MB free of internal storage?!? Is this normal?

I install the custom rom again and then the system use 5,45 GB I think this is too much??

I hope someone can help me :)

Greeting,

Niels

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