ICH Volume Calculator
HealthEstimate intracerebral hemorrhage volume from CT scan measurements using the ABC/2 method, with hemorrhage size context for reviewing scan reports.
Diameter A (Largest Diameter)
cm
Diameter B (Perpendicular to A)
cm
Number of CT Slices with Hemorrhage
slices
CT Slice Thickness
cm
Estimated Hemorrhage Volume
0mL
Hemorrhage Size Category
โ
Informational estimate only. This calculator is not a substitute for a radiologist's or neurologist's interpretation of the CT scan. Always discuss hemorrhage size and its significance with your care team.
What is a ICH Volume?
The ICH Volume Calculator estimates intracerebral hemorrhage volume from CT scan measurements using the ABC/2 method, a fast bedside approximation technique described by Kothari et al. (Stroke, 1996). It multiplies the largest hemorrhage diameter (A), its perpendicular diameter (B), and the craniocaudal extent (C, calculated from the number of CT slices and slice thickness), then divides by 2.
Enter your three measurements below to see the estimated hemorrhage volume in milliliters and a general size category. For a related acute neurological parameter, see the Cerebral Perfusion Pressure Calculator; for a related hemodynamic tool, see the MAP Calculator.
How to use this ICH Volume calculator
- Enter Diameter A, the largest hemorrhage diameter measured on the CT slice where it appears largest, in centimeters.
- Enter Diameter B, the diameter perpendicular to A on that same slice, in centimeters.
- Enter the Number of CT Slices with Hemorrhage โ how many consecutive slices show the hemorrhage.
- Enter the CT Slice Thickness used for the scan, in centimeters.
- Review the Estimated Hemorrhage Volume and Hemorrhage Size Category, and discuss the result with your neurology or neurosurgery care team.
Formula & Methodology
The ABC/2 method estimates hemorrhage volume as: Volume (mL) = (A ร B ร C) รท 2 where: - A = largest hemorrhage diameter (cm) - B = diameter perpendicular to A (cm) - C = craniocaudal extent = number of CT slices with hemorrhage ร slice thickness (cm) Worked example: A hemorrhage measuring 4 cm (A) by 3 cm (B), visible across 6 CT slices at 0.5 cm slice thickness (C = 6 ร 0.5 = 3 cm), gives a volume of (4 ร 3 ร 3) รท 2 = 18 mL, categorized as a smaller hemorrhage under 30 mL, per the ABC/2 method described by Kothari et al. (Stroke, 1996;27(8):1304-1305).
Frequently Asked Questions
The ABC/2 method is a quick, widely used technique for estimating the volume of an intracerebral hemorrhage from a CT scan, approximating the hemorrhage as an ellipsoid shape. It was described by Kothari RU, et al. in Stroke, 1996;27(8):1304-1305, and remains a standard bedside estimation method in clinical practice.
A is the largest diameter of the hemorrhage on the CT slice where it appears largest, B is the diameter perpendicular to A on that same slice, and C approximates the craniocaudal (vertical) extent of the hemorrhage, calculated as the number of CT slices containing hemorrhage multiplied by the slice thickness. All three measurements are in centimeters.
Dividing by 2 accounts for the fact that an ellipsoid's volume formula (4/3 ร ฯ ร a ร b ร c, using the radii) simplifies to approximately (A ร B ร C) รท 2 when using full diameters instead of radii and rounding ฯ/6 to approximately 0.52 โ 1/2. This makes the method fast to calculate at the bedside without needing a calculator for ฯ.
The ABC/2 method is a reasonably close approximation for hemorrhages that are roughly ellipsoid in shape, but it can be less accurate for very irregular hemorrhage shapes, where dedicated volumetric software analysis is more precise. It remains popular because it is fast and requires only a ruler or the CT scanner's built-in measurement tool.
Larger intracerebral hemorrhage volumes have been consistently associated with worse neurological outcomes and higher mortality in published outcome studies, and volume is a key input to several validated prognostic tools used by neurologists. It's one of several factors, alongside hemorrhage location, patient age, and neurological exam findings, that inform overall assessment.
This calculator uses illustrative size categories of under 30 mL, 30-60 mL, and 60 mL or more, reflecting thresholds commonly discussed in intracerebral hemorrhage outcome research and prognostic scoring systems. These categories provide general context only โ actual prognosis depends on many additional factors your neurologist will assess.
If your radiology report or CT viewer provides the three diameter measurements, you can enter them here to see the ABC/2 estimate โ but always rely on your neurologist's or neurosurgeon's interpretation of the actual scan and clinical significance, not on this tool alone.
No โ this calculator is for informational and educational purposes only. Interpreting a CT scan for intracerebral hemorrhage, including its size, location, and clinical significance, requires a qualified radiologist or neurologist reviewing the actual imaging, not just three measurements entered into a formula.
Yes โ location (for example, deep versus lobar, or brainstem involvement) is at least as important as volume in determining prognosis and treatment options, and this calculator does not account for location at all. It focuses solely on the ABC/2 volume estimation method.
Slice thickness, multiplied by the number of CT slices showing hemorrhage, approximates diameter C (the craniocaudal extent). Standard CT slice thickness for head imaging is often around 0.5 cm (5 mm), but check your specific scan protocol for the exact value.
Mean arterial pressure, calculated by the [MAP Calculator](/map-calculator/), is relevant to maintaining adequate cerebral perfusion in patients with intracerebral hemorrhage, but it measures a completely different clinical parameter than hemorrhage volume. Both may be tracked together in acute neurological care.
They are related but distinct concepts โ cerebral perfusion pressure (see the [Cerebral Perfusion Pressure Calculator](/cerebral-perfusion-pressure-calculator/)) reflects blood flow adequacy to the brain, while ICH volume reflects the physical size of the bleed itself. Both are tracked in the acute management of intracerebral hemorrhage but answer different clinical questions.
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