The you plan to use (e.g., 1045 Carbon Steel, 4140 Alloy). The type of load (steady, light shock, or heavy shock).
Visit the official ASME website (asme.org). Navigate to the "Standards" section and search for "B106.1M." Asme B106.1m Pdf
Still widely taught and used as the "gold standard" for basic shaft sizing. 1M formulas for a specific shaft application? The you plan to use (e