How this calculator works
ABC/2 approximates an ellipsoid using the largest CT diameter, its perpendicular diameter on the same slice and craniocaudal extent. Weighted mode follows the original slice method: count areas above 75% of the largest as 1, 25% through 75% as 0.5 and below 25% as 0. This is a rough imaging estimate. Irregular or separated haemorrhages need segmentation rather than an invented shape adjustment. The result is an estimate for information only and is not medical advice.
Formula
Volume = A × B × C / 2. C = effective slice count × slice thickness. In cm, the result is cm³, equal to mL.
Worked example
A 4 cm by 3 cm haemorrhage on four 0.5 cm slices gives C 2 cm and volume 12 mL. Three full plus two half-weight slices also give effective count 4.
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Frequently asked questions
Are A and B measured on different slices?
No. Use the greatest diameter and its perpendicular on the same largest haemorrhage slice.
Can slices have different thicknesses?
This page assumes a common thickness. Use segmented volume or a suitable method for variable slice spacing.
Why is there no irregular-shape divisor?
A universal replacement divisor is not assumed. ABC/2 is less reliable for irregular, multifocal or multilobular haemorrhage.