Nigel Wesson, 32, had been working at the training centre owned by the Chipperfield circus dynasty near Oxford for 10 days when he was attacked by 25-stone Rajah as he reached into his cage to close a partition.
Speaking from his bed at John Radcliffe Hospital in Oxford, he told the Mirror newspaper: "He was going chomp, chomp, chomp after putting all his claws into it. When the arm came off you could hear it ripping with a crunching sound. It really, really hurt - the most painful thing ever."
The former riding instructor, whose calmness in the immediate aftermath of Wednesday's accident astonished colleagues, once again displayed his extraordinary sangfroid, saying: "It's just one of those things. The tiger was only doing what comes naturally. I wouldn't want him killed even though it quite wrecked my day."
Staff at Chipperfield's Farm in Chipping Norton, which is used to winter big cats before they are rented out to circuses in the summer, found Mr Wesson screaming in agony seconds after the attack. He said: "The whole thing happened in 60 seconds. I just remember the noise and awful pain. After the arm came off, I staggered backwards, ran around the corner and shouted at the one of the lads to put a tourniquet on it.
"Luckily, I didn't lose my presence of mind. I knew I had to get a tourniquet on and I couldn't do it one-handed."
Mr Wesson said working at the Chipperfield centre had been the realisation of a long-held ambition - and added that he has a soft spot for tigers.
He said: "I've always wanted to work outside and I love animals. I'd never worked with tigers before but I was building up a relationship with them. They seemed quiet, real softies.
"I picked up what to do with them as I went along. It didn't appear to be too difficult. When Rajah got me at first I didn't know whether he was playing or what."Reuse content