Upgrade times listed are different than actual time needed

Im pretty sure iron mine takes longer than 11 hours to upgrade, iron is the longest timewise for all resource upgrades.

Just checked... Level 13->14 takes me 24 hours and some minutes, with lvl 20 main

My be it's right time. but i see one time before click upgrade button and other time after click. And the difference is greater, the greater the level of the main building.
when main level 20:

when main level 20

sc12.jpg (50.12 KiB) Viewed 1157 times

and
when main level 2:

when main level 2

sc34.jpg (47.12 KiB) Viewed 1157 times

I think, these times must be always equal.

I also have this problem, have done since I started playing and am now level 14