Bladder Volume Calculator

Created by Łucja Zaborowska, MD, PhD candidate
Reviewed by Bogna Szyk and Jack Bowater
Based on research by
Bih, L.; Ho, C.; Tsai, S.; Lai, Y.; Chow, W. Bladder Shape Impact on the Accuracy of Ultrasonic Estimation of Bladder Volume; Archives of Physical Medicine and Rehabilitation; 1998
Last updated: Jun 05, 2023

This bladder volume calculator provides you with the precise urinary bladder volume in a few easy steps, which allows you to assess the organ for both its post-void residual volume and maximal capacity quickly.

In the text below, we supply you with all the essential information on the evaluation of the urinary bladder volume in ultrasound, bladder capacity calculation, and details on how much can a bladder hold in different circumstances.

Disclaimer: We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace professional medical advice.

How to use the bladder volume calculator?

To calculate the bladder size, you first need to perform the following measurements:

  1. Find the three dimensions of the bladder:
  • maximal transverse (width);
  • anterior-posterior (height); and
  • longitudinal (length).
  1. Evaluate the shape of the bladder. Our calculator will automatically multiply your result by the coefficient that corresponds to your chosen shape. You can also choose your own coefficient value by clicking the advanced mode button.
  • Ellipsoid - coefficient 0.81
  • Cuboid - coefficient 0.89
  • Triangular prism - coefficient 0.66
  • Prolate ellipsoid - coefficient 0.52
  • I don't know* - coefficient 0.77

Our bladder volume calculator allows you to find the bladder size of bladders of an irregular shape (bladders that cannot be classified into any other category).

  1. Your calculated bladder size will appear along with the mean error for the calculation, estimated to be around 12.7%.

How to calculate bladder volume?

Our bladder volume calculator is based on the simplest, most efficient, and most commonly used formula:

bladder volume = width * height * length * coefficient

The coefficient value may vary for particular methods, bladder shapes, or individual research papers. For example, it might take values of: 0.52, 0.66, 0.77, 0.81 or 0.89, as presented in the section above. These coefficients require the measurements to be in centimeters and milliliters.

We'd also like to propose some different, or more advanced methods, used mostly for research purposes:

  1. bladder volume = exp(C1+C2 * ln(A1)+ C3 * ln(A2)),


  • A1 = maximal longitudinal cross-section;
  • A2 = maximal transverse cross-section;
  • C1 = 0.8304;
  • C2 = 0.5625; and
  • C3 = 0.7211.
  1. bladder volume = height * depth * 0.66 - for a single saggital scan.

  2. Children: bladder volume = (years of age + 2) × 30 ml.


  • Bladder Shape Impact on the Accuracy of Ultrasonic Estimation of Bladder Volume
  • Measurements of urinary bladder volume: comparison of five ultrasound calculation methods in volunteers

Bladder volume on ultrasound

Bladder volume can be measure during an ultrasound (US) examination using the mathematical methods enumerated above. The ultrasound examination may be performed in a few different ways:

  • Transabdominal US - a view obtained through the skin on your belly;
  • Transvaginal US - a view obtained via the intra-vaginal probe; and
  • Transrectal US - a view obtained via the intra-rectal probe.

Each of these methods serves a different purpose, and are each used in particular situations and clinical findings.

How much can a bladder hold?

The average bladder capacity of a child can be calculated from the equation based on a child's age. To estimate how many ml can a bladder hold, you need to add 2 to a kid's age, and multiply the whole number by 30 ml.

The average adults's urinary bladder can hold around 300-400 ml (it's equal to 10.1-13.5 US ounces - check our volume conversion calculator).

But how many ounces can a bladder hold when it is full?

It's around 24 ounces, or 710 ml. (Some sources even report numbers as big as 34 ounces or 1000 ml!)

The amount of pee stored in your bladder depends on:

Why do I pee too often/not often enough?

Possible causes for passing water not often enough are:

Possible causes for passing water too often are:

  • excessive water intake;
  • undetected pregnancy;
  • diabetes mellitus;
  • certain drugs (for example diuretics);
  • prostate disorders;
  • urinary track infections;
  • insufficiency of the pituitary gland; and
  • urinary bladder cancer ⤵️

🚬 Smoking increases the risk of developing multiple types of neoplasms, including pancreas cancer, lung cancer and urinary bladder cancer!

Łucja Zaborowska, MD, PhD candidate
Bladder shape
Dimension 1
Dimension 2
Dimension 3
cu in
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