
By a hair's breadth
By a nose hair / By a nose / By a wisker / By a hair / By that much! / Within an ace of

Per un pelo 
Per un soffio
By a nose hair / By a nose / By a wisker / By a hair / By that much! / Within an ace of

Per un pelo 
Per un soffio
Meanings
By a very small distance or amount
Examples
I just barely passed my final exam by a wisker
Ho superato l'esame con il minimo dei voti, ce l'ho fatta per un pelo
The skeet champion missed the 25th skeet by that much, but it was enough to make him lose the championship
Il campione di tiro ha mancato il venticinquesimo piattello per un soffio ma tanto รจ bastato per fargli perdere il titolo
This time I had a very close call; I made it by a hair's breadth!
Questa volta l'ho vista brutta; l'ho scampata per un pelo!
I made the train by a hair: one more minute and I would have missed it
Ho preso il treno per un pelo, ancora un minuto e l'avrei perso