Bladder Volume Calculator - Adult & Child Estimates
Estimate bladder volume for adults from ultrasound measurements, or for children from age alone. Free, instant results with multiple shape options.
How to Use the Bladder Volume Calculator
- Choose Adult or Child.
- For Adult: enter width, height, and length (with units), and select the bladder shape.
- For Child: enter age in years.
- View the estimated bladder volume instantly.
Features of the Bladder Volume Calculator
- Estimates adult bladder volume from ultrasound-style width, height, and length measurements.
- Supports five standard shape coefficients, plus a custom coefficient option.
- Estimates expected bladder volume for children from age alone.
- Accepts measurements in centimeters, meters, or inches.
- Free to use with no sign-up required.
Bladder Volume Formulas
Adult bladder volume is commonly estimated from three ultrasound measurements combined with a shape-based correction coefficient, since the bladder is not a perfect geometric shape.
Bladder Volume = Width × Height × Length × Coefficient
For children, bladder volume is commonly estimated from age alone using a standard pediatric formula:
Bladder Volume for Children = (Age + 2) × 30
Bladder Shape Coefficients
| Shape | Coefficient |
|---|---|
| Ellipsoid | 0.81 |
| Cuboid | 0.89 |
| Triangular Prism | 0.66 |
| Prolate Ellipsoid | 0.52 |
| I don’t know (default) | 0.77 |
How to Calculate Adult Bladder Volume
Multiply the width, height, and length measurements together, then multiply that result by the coefficient for the assumed bladder shape.
Suppose you have a width of 8 cm, height of 6 cm, and length of 10 cm, with an ellipsoid shape (coefficient 0.81). Volume = 8 × 6 × 10 × 0.81 = 388.8 mL.
Thus, the estimated bladder volume is 388.8 mL.
Child Bladder Volume by Age (Reference Table)
| Age (years) | Estimated Volume (mL) |
|---|---|
| 1 | 90 |
| 3 | 150 |
| 5 | 210 |
| 8 | 300 |
| 12 | 420 |
Solved Examples on Bladder Volume
1. Adult With Ellipsoid Shape
Example: Width 8 cm, Height 6 cm, Length 10 cm, Ellipsoid (0.81).
Volume = 8 × 6 × 10 × 0.81 = 388.8 mL.
2. Adult With Cuboid Shape
Example: Width 8 cm, Height 6 cm, Length 10 cm, Cuboid (0.89).
Volume = 8 × 6 × 10 × 0.89 = 427.2 mL.
3. Adult With Prolate Ellipsoid Shape
Example: Width 8 cm, Height 6 cm, Length 10 cm, Prolate Ellipsoid (0.52).
Volume = 8 × 6 × 10 × 0.52 = 249.6 mL.
4. Child Bladder Volume by Age
Example: Age 5 years.
Volume = (5 + 2) × 30 = 210 mL.
1. Why does adult bladder volume need a shape coefficient?
The bladder isn’t a perfect geometric shape, so multiplying width × height × length alone overestimates its true volume. The coefficient corrects for the actual shape the bladder most closely resembles on ultrasound.
2. Which shape coefficient should I choose?
Ellipsoid (0.81) is the most commonly used coefficient in clinical bladder ultrasound. If the specific shape isn’t known, the “I don’t know” option (0.77) provides a reasonable general-purpose estimate.
3. Why is the children’s formula based only on age?
Pediatric bladder capacity correlates closely with age, so a simple age-based formula gives a useful expected-volume estimate without requiring ultrasound measurements, which can be harder to obtain reliably in young children.
4. Can I use a custom coefficient?
Yes, selecting “Custom coefficient” lets you enter your own value if you have a coefficient from a specific clinical protocol or study that differs from the standard options listed.
5. Does this calculator provide a medical diagnosis?
No. This tool estimates bladder volume from measurements or age using standard formulas, but it is not a diagnostic tool. Always consult a healthcare professional for medical assessment and interpretation.
6. What units can I enter measurements in?
Width, height, and length can each be entered in centimeters, meters, or inches, and the calculator converts them automatically before applying the formula.