Make a BMI Calculator App with Flutter

What This App Does

A BMI Calculator app serves a specific and growing need in today's mobile-first world. Building one with Flutter means you ship to iOS, Android, and the web from a single codebase, cutting development time dramatically while keeping a native-quality experience.

In this guide we walk through the essential features of a BMI Calculator app, the packages that handle the heavy lifting, and the Dart code that ties everything together.

Main Features

Feature	Why It Matters
Height & Weight Input	Sliders or text fields for metric/imperial units with instant validation
BMI Calculation Engine	Formula: weight (kg) / height (m)^2, categorised into underweight, normal, overweight, obese
History & Trends	Store past results locally and show a chart of BMI over time

How to Make a BMI Calculator App with Flutter

1. Height & Weight Input

Sliders or text fields for metric/imperial units with instant validation

Reach for flutter_form Builder for validated inputs to implement this without reinventing the wheel.

2. BMI Calculation Engine

Formula: weight (kg) / height (m)^2, categorised into underweight, normal, overweight, obese

Reach for fl_chart for history charts to implement this without reinventing the wheel.

3. History & Trends

Store past results locally and show a chart of BMI over time

Reach for fl_chart for history charts to implement this without reinventing the wheel.