The CT formula for the volume of cerebral hemorrhage was the multiplication of the length (L, in cm) and width (W, in cm) of the largest cross-section of the hemorrhagic foci by the number of layers of the hemorrhagic foci (C), and then multiplied by the thickness of each layer of the CT (0.5 cm), and then divided by 2, which means that the volume of the hemorrhage, V = L×W×C×0.5÷2 (in ml). Firstly, the plane with the largest hematoma cross-sectional area was determined by the patient’s craniocerebral CT scan, where L×W is the estimation of the largest cross-sectional area, then C×0.5 is the estimation of the hematoma thickness, and L×W×C×0.5 is the volume estimated by imagining the hematoma as a cube, which is finally divided by 2 because from the largest cross-sectional area to the two sides, the cross-sectional area of the hematoma is getting smaller and smaller. The CT formula for cerebral hemorrhage volume is applicable to the calculation of intracranial hematomas with a certain volume, and is not applicable to diffuse hemorrhages as well as subarachnoid hemorrhages.