it's usually two sizes up...but you can never really be sure to be honest. I'm size 8 in the us, but pakistan 9, 10, and sometimes even 11 in pak. sorry couldn't help ya out more.
in pakistan they either have sizes in 40s or 10s...
i am a size 7 in the uk, and here i am either a 40 or 11.
You being a size 5 uk are a size 38 or 9 in pakistan...