Educational tool, not a diagnosis. This applies a published formula to numbers you enter. Organ volume is interpreted by clinicians alongside body size, symptoms, blood results and other imaging findings.
Discuss any result with the healthcare professional who arranged your scan. A single volume neither confirms nor excludes any condition.
Quick answer: volume = length × width × height × 0.524, with diameters in centimetres. An 11 × 7 × 4 cm spleen is about 161 mL. Splenomegaly is often described above roughly 300–500 mL, but the threshold depends on body size and the reference used.
The spleen volume formula
The spleen is modelled as a prolate ellipsoid using the standard π/6 coefficient. Worked example: a spleen measuring 12.5 × 7.0 × 4.5 cm:
- Multiply the diameters: 12.5 × 7.0 × 4.5 = 393.75
- Apply the coefficient: 393.75 × 0.524 = 206.3 mL
The ellipsoid (π/6) method is standard for organ volume estimation on ultrasound. For the spleen, craniocaudal length over about 12–13 cm is a common screening threshold; volume gives a fuller measure. Reference ranges vary with body size, sex and population.
Spleen size reference figures
| Organ | Commonly cited volume | Enlargement described above |
|---|---|---|
| Spleen (adult) | ≈ 100–300 mL | ≈ 300–500 mL (splenomegaly) |
These are broad orientation figures, not fixed cut-offs. Splenic volume scales with body size, so thresholds are often adjusted for height or body surface area, and interpretation always depends on why the scan was requested.
Splenic index: why it is not the same as splenic volume
The three diameters can come from ultrasound, CT or MRI, and this calculator accepts them from any of the three. The regression below was derived from CT: Prassopoulos and colleagues measured splenic volume directly on CT scans and found that normal adult volumes ranged from about 107 to 315 cm³.
Radiology reports often quote a splenic index rather than a volume, and the two are related but distinct. The splenic index is simply the product of the three diameters, with no geometric coefficient applied:
Splenic volume (ellipsoid) = L × W × T × 0.524
Splenic volume (Prassopoulos CT regression) = 30 + 0.58 × splenic index
Taking the same 12.5 × 7.0 × 4.5 cm spleen from the worked example above:
| Quantity | Calculation | Result |
|---|---|---|
| Splenic index | 12.5 × 7.0 × 4.5 | 393.8 cm³ |
| Volume, ellipsoid | 393.8 × 0.524 | 206.3 mL |
| Volume, Prassopoulos regression | 30 + 0.58 × 393.8 | 258.4 mL |
Those two volume figures differ by 52 mL — about 25%. That is not a rounding discrepancy; they are different models. The ellipsoid formula assumes the spleen is a smooth prolate ellipsoid, which systematically under-reads because a real spleen is more irregular. The Prassopoulos regression was fitted to splenic volumes measured on CT and includes a constant offset, which is why it runs higher. Neither is wrong — but a volume quoted without saying which method produced it is ambiguous, and you cannot meaningfully compare a Prassopoulos volume on one scan with an ellipsoid volume on the next.
| Splenic index | Commonly described as |
|---|---|
| < 120 cm³ | Small |
| 120 – 480 cm³ | Within the usual adult range |
| > 480 cm³ | Enlarged — splenomegaly |
| > 1,000 cm³ | Marked splenomegaly |
The 480 cm³ splenic index threshold and the Prassopoulos regression (Prassopoulos et al., European Radiology, 1997) are widely cited in the radiology literature. Like all such figures they are population-derived orientation values, not diagnostic criteria, and splenic size scales with body habitus. Record which method you used, and keep to the same one when following a spleen over time.
Frequently asked questions
How is spleen volume calculated?
With the ellipsoid formula: volume = length × width × height × 0.524, using three perpendicular diameters in centimetres. A spleen measuring 11 × 7 × 4 cm gives 308 × 0.524 ≈ 161 cm³. Because 1 cm³ equals 1 mL, the result is in millilitres.
What is a normal spleen volume?
Adult splenic volume is commonly cited as roughly 100 to 300 mL, though it varies with body size, sex and the reference source. Volume above about 300 to 500 mL is often described as splenomegaly, but the threshold depends on the patient and the guideline used.
How is splenomegaly assessed on ultrasound?
Often by the spleen's craniocaudal length rather than volume — a length over about 12 to 13 cm is a common screening threshold. Volume gives a fuller picture but needs three measurements. Both are interpreted alongside the clinical context, since a normal-sized spleen does not exclude disease and a large one is not always pathological.
Can I use this for kidney volume?
Partly. The geometry is the same, but kidneys need their own reference ranges and, in polycystic kidney disease, height-adjusted total kidney volume. Use the kidney volume calculator, which covers both kidneys and the Mayo imaging classes.
How accurate is the ellipsoid method for these organs?
It is a good approximation for a regularly shaped organ but is only an estimate. The spleen in particular can be irregular, and because three measurements are multiplied, errors compound. Cross-sectional imaging with 3-D reconstruction is more accurate when precision matters.
Does this work as a splenic index calculator?
Yes. The splenic index, also called the spleen index, is length × width × thickness, the three diameters multiplied without the 0.524 ellipsoid coefficient. This splenic index calculator reports both figures from the same three measurements, so you can read the index or the estimated splenic volume.
References
- Prolate ellipsoid volume formula — standard geometric derivation, V = (π/6) × d₁ × d₂ × d₃.
- Prassopoulos P, Daskalogiannaki M, Raissaki M, Hatjidakis A, Gourtsoyiannis N. Determination of normal splenic volume on computed tomography in relation to age, gender and body habitus. Eur Radiol 1997;7(2):246–248. PMID 9038125. Springer
- Strijk SP, Wagener DJ, Bogman MJ, de Pauw BE, Wobbes T. The spleen in Hodgkin disease: diagnostic value of CT. Radiology 1985;154(3):753–757. doi:10.1148/radiology.154.3.3969481. The origin of the splenic index.
- Lamb PM, Lund A, Kanagasabay RR, et al. Spleen size: how well do linear ultrasound measurements correlate with three-dimensional CT volume assessments? Br J Radiol 2002;75(895):573–577. doi:10.1259/bjr.75.895.750573