Bladder Volume Calculator
Estimate bladder volume from ultrasound measurements using the ellipsoid formula. Enter the bladder's width, height (cranio-caudal), and depth in centimetres, and this calculator returns the approximate volume in millilitres.
Rates and fees change frequently. Always confirm the current figures
with the official authority before relying on this result.
Formula
Bladder Volume (mL) = 0.52 × Width × Height × Depth (all in cm)
- The bladder is approximated as an ellipsoid, whose volume is 0.52 (≈ π/6) times the product of its three dimensions.
- Measure width, height (cranio-caudal), and depth (antero-posterior) in centimetres on ultrasound.
- Because 1 cm³ = 1 mL, the result comes out directly in millilitres.
- The 0.52 coefficient is a common clinical approximation; some protocols use slightly different factors.
- A normal adult bladder holds roughly 300–500 mL; a post-void residual over ~100 mL may warrant review.
8 × 7 × 6 cm bladder
Inputs
- Width: 8 cm
- Height (cranio-caudal): 7 cm
- Depth (antero-posterior): 6 cm
0.52 × 8 × 7 × 6 = about 175 mL of estimated bladder volume.
Frequently asked questions
How is bladder volume estimated?
By treating the bladder as an ellipsoid: volume ≈ 0.52 × width × height × depth, with all three measured in centimetres from ultrasound.
Why the 0.52 factor?
0.52 approximates π/6, the geometric constant for the volume of an ellipsoid relative to its bounding box. It is the most widely used clinical coefficient.
What is a normal bladder capacity?
An adult bladder typically holds about 300–500 mL when comfortably full, though urge to void usually begins around 150–250 mL.
What is post-void residual?
It is the volume left in the bladder right after urinating. Persistently high residuals (often >100 mL) can indicate incomplete emptying and may need evaluation.
How accurate is the ellipsoid estimate?
It is an approximation — a partially filled or irregularly shaped bladder departs from a true ellipsoid, so treat the value as a clinical estimate.