3 inch biceps in 6 months? I heard that you need at least to gain 10lbs of muscle on your whole body to gain at least 1 inch to your arms. I am kind of skeptical about this You are 6'0ft tall so you could easily achieve bigger arms than most I would say in 6 months if you train right you might be able to gain 1 inch on your arms. Again you are a beginner so your gains should come quick