There are three theories about his age when he died: twenty-four according to the Okita family grave stone; twenty-five according to documents held by the Okita family; and twenty-seven, if, as described in Shikanosuke KOJIMA's "Ryoyushiden", he was twenty-two when he left for Kyoto.
なお、没時年齢については沖田家累代墓碑の24歳、沖田家文書の25歳、『両雄士伝』（小島鹿之助）における上洛時の年齢（22歳）から計算した27歳の3説が存在する。