Bladder scanning is used to check for urinary retention, to measure post-void residual volume and to avoid unnecessary catheterisation. A post-void residual over about 100–200 mL suggests incomplete emptying.
How to use the Bladder Volume Calculator
- Length
- Width
- Height
- Correction factor
- Measured after voiding?
Results update as you type, and every field accepts the units shown in its menu.
How it works
Measure the bladder in transverse and sagittal views and enter the three diameters. Choose a correction factor.
Inputs explained
| Field | What to enter |
|---|---|
| Length | Units: cm, in, m, ft, mm |
| Width | Units: cm, in, m, ft, mm |
| Height | Units: cm, in, m, ft, mm |
| Correction factor | Choose one: 0.52 (ellipsoid), 0.625, 0.7 |
| Measured after voiding? | Choose one: No, Yes |
Example values
How the main result changes when Length changes and everything else stays at the example values above:
| Length (cm) | Bladder volume (mL) |
|---|---|
| 4 | 87 |
| 6 | 131 |
| 8 | 175 |
| 10 | 218 |
| 12 | 262 |
| 16 | 349 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Volume (mL) = length × width × height (cm) × correction factor (0.52 ellipsoid; 0.625–0.7 commonly used for bladder shape)
Worked example
Inputs — Length: 8 cm; Width: 7 cm; Height: 6 cm; Correction factor: 0.52 (ellipsoid); Measured after voiding?: No.
Results — Bladder volume = 175 mL; Interpretation = Pre-void volume.
Key terms
- PVR
- Post-void residual.
Frequently asked questions
What is a normal bladder capacity?
About 400–600 mL in adults.
What is a normal post-void residual?
Under 50 mL is normal; over 200 mL is generally abnormal.
Which correction factor is best?
0.52 is standard for an ellipsoid; many scanners use around 0.625–0.7 because the bladder is not a perfect ellipsoid.