I just having hard time getting info on how Antenna gain affect the signal levels. I just wonder how much signal level change i would get moving from 24.5Dbi antenna to 33Dbi one, as i heard with 33Dbi antenna wireless links are able to extend more than 50km, so let me give you example right now i have signal levels of 63tx/58rx with 24.5 Dbi antenna gain, if i move to 33dbi antenna is it easy to calculate like 33-24.5=8.5 so it will reflect to 63-8.5=54.5/58-8=49.5 Dbm? or is it calculated different?
https://en.wikipedia.org/wiki/Antenna_gain#Example_calculation
Looks like some rocket science 
See also https://www.simplewifi.com/pages/antenna-basics
According to their table it seems for your 14km you need a “Parabolic Grid 24 dBi Directional Antenna”, or better.
But they also say “As a rule of thumb to remember, high dBi rating = further distance covered, but not area.”
Regarding calculation: I think it’s unfortunately not that simple like in your calculation, but I’m not an expert in this field; just guessing.
This is indeed the math. If the TXpower is allowed in your regulatory domain. The EIRP will be 8.5 dBm higher if the same TXpower at the radio is maintained. So normally by setting the antenna gain at 33 dBi the TXpower is reduced with 8.5 dBm to obtain the same EIRP (limit region dependent, typically 30 dBm, the radio will me set at -3dBm, but might run at 2dBm because that’s the lowest possible power setting of the chipset). The signal received at the other end will then be the same, but this antenna will be 8.5 dBi more sensitive for reception.
There is a link calculator : https://mikrotik.com/calculator
And selection guides: https://i.mt.lv/cdn/rb_files/antenas-160404123306.pdf
thanks for answers, i tried to use Link calculator but i have no info of AP device im connecting so i just guessed it has 33dbi gain. and sadly if i choose my device which is ldf-5 it doesnt let me change antenna gain to 33dbi so ive chosen mant30 on both sides which let me choose gain sensitivity and output power and got -48Dbm but i guess its for perfect conditions. signal restrictions in turkey not very strict and i live in a rural area and there only a few houses between that 14km link. so im thinking to set my device to superchannel for getting max signal possible, but if i can get a good connection with lower txpower i may lower it. Only thing i want is stable ping between the access point and me.
Good day.