Estimate bladder volume from ultrasound length, width and height, with post-void residual interpretation.
Result
How to use this tool
Use the length, width and height from the ultrasound report, in centimetres.
Enter the post-void residual in the advanced section when it was measured.
The volume and its band appear instantly, with residual guidance when provided.
High residuals or inability to void need prompt clinical advice, not self-management.
Formula & worked example
A bladder measuring 10 cm by 8 cm by 6 cm gives 0.52 x 10 x 8 x 6 = 249.6 mL.
Limitations — read this before you rely on it
Educational estimate from the ellipsoid formula only. This tool is for education only and is not medical advice. Talk to a clinician about any result that worries you, and never change treatment because of a calculator result.
Frequently asked questions
The ellipsoid formula: 0.52 x length x width x height, all in centimetres, giving millilitres. It is the standard bedside estimate from ultrasound measurements.
Functional capacity is usually around 300-550 mL in adults, but it varies with age, sex and habit. A single measurement is only part of the picture.
The urine left in the bladder straight after voiding. Up to about 50 mL is commonly considered normal; higher values deserve clinical review.
No. Length, width and height come from an ultrasound scan, so this calculator is for interpreting measurements a clinician has already taken.
A very large volume or a high residual can signal retention or obstruction and should be discussed with a clinician, especially with pain or inability to pass urine.