Purpose of (1 + headroom) / (high_water_mark) , can i avoid this in my ram sizing?

Hello Team,

Could you pls tell me what is the purpose of below in sizing : (1 + headroom) / (high_water_mark)

What is 1 in above Formula ?

My Total metadata is = ~ 8GB
But when am doing 8GB * (1+0.25)/(0.7) = 14 GB (Its directly doubling the ram requirement)

select ((((50+50+64)*27052304)*1.75/1024/1024)*2); = 14808 MB =14 GB

Please tell me how to avoid the use of this - > (1 + headroom) / (high_water_mark) , is it ok to ignore this ?

Regards,
Ash