Merwins EPV Calculator

Merwin’s EPV Calculator calculates the volume of a spherical cap from an imaginary cross section through the middle of the cap.

Using a complex polynomial, Merwin’s equation utilizes the width, height and thickness measurements of the cross-section of a spherical cap.

To demonstrate potential utility, an illustrative example of normative curves, including the 10th, 50th and 90th percentile lines, as well as derived percentile, is generated to demonstrate how this equation could be used in real-world practice. The example curve presented has no utility beyond that of an illustrative example. In the example presented data is collected in the form of lengths in centimeters and time as weeks and days.


Key Features:

- Enter the sample name and time in weeks and days
- Easily enter width, height and thickness of the spherical cap
- Calculates the spherical cap volume immediately using mathematical modeling
- The volume result is immediately plotted on a sample normative curve, with normal values shown in green and alert values shown in red
- The volume result and normative curves can be viewed in landscape mode for a larger plot
- Results can be easily shared using Apple’s standard share tool
- Data can be easily updated and recalculated, or cleared for a new sample
- Calculates placenta weight percentile after delivery, and if birth weight is known, the birth weight to placenta weight ratio.