Project - Building a Personal Health Metrics Calculator GUI

Part 2 of 2: GUI Development

TL;DR

I wrapped the calculation engine from Part 1 in a PyQt5 graphical interface, creating a desktop application where users input their metrics through form fields and receive instant results. The GUI uses 5 different widget types (text inputs, radio buttons, dropdowns, buttons, and display areas) to collect data and present all 7 health metrics in a clean, formatted output.

The Objective

The back-end functions from Part 1 work perfectly in a Python console, but asking users to run scripts and type function calls isn't practical. A graphical interface removes this barrier entirely.

Goal: Build a user-friendly desktop application that collects health data through intuitive form controls and displays calculated metrics without requiring any coding knowledge from the user.

Tech Stack & Context

Framework: PyQt5 (Python bindings for Qt)

Integration: Imports health_metric function from Part 1 module

Limitation: No input validation on modular functions. This means it will accept any text string or integers

PyQt5 Widgets Used

Each input type was matched to the most appropriate widget for usability:

QLineEdit

Text input for weight, height, age

QRadioButton

Binary choice for sex selection

QComboBox

Dropdown for activity level

QPushButton

Triggers calculation

QTextEdit

Read-only results display

QLabel

Field labels and headings

My Approach

I tried to structure the GUI as it will appear to the user. Starting with the input widgets, connecting them to the backend functions, and ending with the output display.

Set up the base application: Initialized QApplication and QWidget, set dimensions (400×570px), title, and created a vertical layout container for all elements.

Built input widgets: Created QLineEdit fields for weight/height/age, QRadioButtons for sex (grouped with QButtonGroup), and a QComboBox dropdown with 5 activity levels.

Created translation function: The dropdown returns strings like "1 = Sedentary" but our function needs integers. Built a helper function to convert these to the required 1-5 values.

Wired the processing logic: Connected the Run button to a function that extracts all inputs, converts types appropriately, calls the health_metric function, and displays results in a read-only QTextEdit.

Key decision: I used a separate translation function for the activity dropdown rather than storing just integers. This keeps the dropdown user-friendly ("Moderately active" is clearer than "3") while maintaining clean separation between UI labels and data values.

Health Metrics Calculator GUI — **Figure 1: Complete GUI Application** The finished interface showing all input fields, the Run button, and the formatted results display area with calculated health metrics.

Key Outcomes

5 Inputs → 7 Outputs

Users input just 5 fields and receive all health metrics instantly in a formatted, easy-to-read display area.

Clean Separation of Concerns

GUI code handles presentation only. All calculation logic stays in the imported Part 1 module, making both easier to maintain & debug.

Back to Part 1: Back-End Development

Reflection

Building this GUI taught me how important it is to plan widget-to-function mapping before writing code. The dropdown translation issue, for example, would have been avoided with better upfront design.

Future improvements would include: adding input validation (preventing negative numbers or text in numeric fields), implementing unit conversion toggles (metric/imperial), and perhaps adding visual charts to display results graphically rather than as text only.

Tools & Technologies

Python PyQt5 QWidgets Modular Imports

Building a Health Metrics Calculator GUI