Ellipsoid Organ Volume Calculator

The prostate ellipsoid preset uses 0.52. General ellipsoid, testis ellipsoid, thyroid lobe, kidney, spleen, ovary and uterus use exact π/6. For the same diameters, 0.52 gives volumes about 0.69% lower than π/6.

AP × longitudinal × transverse × 0.52, with dimensions in cm (PI-RADS v2.1). PI-RADS v2.1 and the AIUM prostate ultrasound parameter, revised 2025, specify 0.52 for ellipsoid volume estimation. MacMahon’s bullet formula, π/4.8, was evaluated against planimetry in 138 brachytherapy patients; this calculator uses its rounded coefficient, 0.65. For PSA density, use the Prostate volume calculator.

ESUR-SPIWG 2025 suggests 0.52 × L × W × H for testicular ultrasound volume in adult male infertility evaluation; the formula recommendation is weak. Its hypotrophy thresholds are right <12 mL or left <11 mL, based on lower reference limits in healthy, fertile men. These thresholds are not applied by this calculator. Its testis ellipsoid option uses exact π/6. The ACR–AIUM–SPR–SRU and AIUM scrotal ultrasound parameters, revised 2025, permit Lambert’s formula, 0.71 × L × W × H. Report the diameters and formula used. In Sakamoto’s study of 40 testes from 20 older men undergoing orchiectomy for prostate cancer, Lambert had the smallest mean difference from water-displacement volume. Volume alone does not establish fertility.

The thyroid-lobe preset estimates one lobe using π/6 × L × W × D. In a cadaver ultrasound study, Brunn et al. derived a correction factor of 0.479 against displacement measurements; for identical dimensions, π/6 gives approximately 9.3% higher values. No thyroid reference-range interpretation is applied.

In 85 patients undergoing urodynamics, 0.52 was the only one of four tested coefficients without a statistically significant difference from catheter volume (Araklitis 2019). The accessible abstract does not specify the ultrasound route or dimensional measurement protocol; applicability to other settings is uncertain.

The ACR abdominal ultrasound practice parameter says a post-void residual may be quantified and reported; it sets no volume threshold.

In 20 adult volunteers, ultrasound ellipsoid volumes averaged 25% (45 mL) below MRI voxel-count volumes and had poor repeatability (Bakker 1999). Applying the ellipsoid formula to MRI also underestimated volume, indicating that kidney shape was a major limitation. This preset provides geometry only, without a correction factor.

The ACR abdominal ultrasound parameter, revised 2026, notes that splenic length and volume may help assess enlargement. Chow et al. published height- and sex-adjusted ultrasound references; those references are not applied to this calculator’s geometric estimate.

Ovarian upper limits from Pavlik 2000: 20 cm³ premenopausal and 10 cm³ postmenopausal, from women 25–91 years old. Pavlik used 0.523; this calculator’s ovarian preset uses exact π/6.

For uterine centiles use the dedicated Kelsey tool; the studies pooled by Kelsey used 0.5 × L × W × H rather than π/6.

Ovarian volume calculator · Uterus volume calculator

Which formula does each preset use?

See Ellipsoid estimates, Bladder, Testis and Prostate for the preset coefficients and formula limitations.

How is bladder volume calculated on ultrasound?

The bladder preset uses 0.52 × length × width × depth with dimensions in cm and volume in mL. See Bladder for the study context and measurement limitations.

What is the Lambert formula for testicular volume?

See Testis for Lambert’s formula, the calculator’s exact π/6 alternative and the guideline comparison.

How is thyroid lobe volume calculated?

See Thyroid lobe for the per-lobe formula, the Brunn comparison and the absence of reference-range interpretation.

How is splenic volume calculated?

This calculator's spleen preset applies the ellipsoid formula, π/6 × length × width × depth, as a geometric estimate. See Spleen for the reference-method limitations.