# Merwins EPV Calculator

> Calculates spherical cap volume and placenta weight percentile using Merwin's equation. (iPhone/iPad app by Harperfection Corporation.)

- Source: https://appshunter.io/ios/app/merwins-epv-calculator/id1062647500 (this page in markdown: same URL + `.md`)
- Developer: [Harperfection Corporation](https://appshunter.io/developer/406488551)
- Category: Utilities, Productivity
- Price: Free
- Rating: 5.00/5 from 8 App Store ratings
- Age rating: 4+
- Requires: iOS 17.6 · 25 MB
- Languages: English
- Released: 2015-12-10
- Data updated: 2026-08-07
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/merwins-epv-calculator/id1062647500/reviews.md

## What is 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.

## Key features

- Calculates spherical cap volume
- Uses Merwin's equation
- Plots results on normative curves
- Calculates placenta weight percentile
- Supports landscape mode for plots
- Easy data entry and sharing


## Frequently asked questions about Merwins EPV Calculator

### What is Merwins EPV Calculator used for?

Merwins EPV Calculator is used to calculate the volume of a spherical cap based on its cross-section measurements (width, height, thickness) using Merwin's equation. It also calculates placenta weight percentile.

### How accurate is Merwins EPV Calculator?

The app utilizes a complex polynomial equation for calculations. It is rated 5.0 stars from 8 ratings, indicating high user satisfaction with its accuracy and utility.

### What devices does Merwins EPV Calculator support?

Merwins EPV Calculator is available for iPhone and iPad devices, making it accessible to a wide range of Apple users.

### Is Merwins EPV Calculator free to use?

Yes, Merwins EPV Calculator is completely free to download and use, with no in-app purchases or advertisements.

### How often is Merwins EPV Calculator updated?

The app was last updated on September 12, 2024, indicating ongoing support and potential for future improvements. It has had multiple updates since its release in 2015.

### Can I share my calculation results from Merwins EPV Calculator?

Yes, results from Merwins EPV Calculator can be easily shared using Apple's standard share tool, allowing for convenient distribution of data.

### What is the age rating for Merwins EPV Calculator?

Merwins EPV Calculator has an age rating of 4+, meaning it is suitable for users of all ages.

### Does Merwins EPV Calculator have ads?

No, Merwins EPV Calculator is ad-free, providing an uninterrupted user experience.

## Version history (last 5 releases)

### 17 — 2024-09-12

Support for iOS 18

### 16 — 2024-01-13

Expanded EPV percentiles

### 15 — 2023-11-07

Adjustment to decimal display for BW%, PW% and BW:PW ratio fields

### 14 — 2023-11-02

Adjustments to %ile display

### 13 — 2023-10-31

Birth weight percentile calculations

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-07.*