Case Study - MedTech body composition app – scientific precision meets user‑friendly design
A MedTech mobile health (mHealth) app for iOS and Android implementing multiple research‑validated body composition formulas – from simple methods like YMCA to advanced skinfold caliper techniques like Jackson & Pollock 7‑site measurements.
- Client
- Body Fat Calculator (PRO)
- Year
- Service
- MedTech Mobile App Development, iOS & Android, React Native, Scientific Implementation
Overview
In digital health and MedTech, accurate body composition assessment is crucial for tracking progress and making informed decisions about training and nutrition. While many simple calculators exist, there was a clear need for a comprehensive mobile health app that implements multiple scientifically validated formulas with professional‑grade accuracy across iOS and Android.
The Body Fat Calculator (PRO) project aimed to bridge this gap by providing both free and professional methods in a native MedTech app – ranging from simple circumference measurements to advanced skinfold techniques using body fat calipers. Each formula was meticulously implemented following original research papers and validated against existing standards. The app also educates users on proper caliper use, pinch technique, and repeatable site measurements for reliable results.
What we did
- MedTech
- HealthTech
- mHealth
- Digital Health
- iOS app development
- Android app development
- React Native development
- iOS & Android deployment
- Scientific formula implementation
- Skinfold calipers
- Body fat calipers
- RevenueCat integration
- Native UI/UX design
- App Store optimization
Technical Implementation
We developed the native mobile application using React Native and Expo, ensuring a high-quality experience on both iOS and Android platforms:
- Cross-Platform Development.
Built with React Native and Expo for consistent performance and native feel across iOS and Android devices, while maintaining a single codebase.
- Research-Based Implementation.
Every calculation method was implemented directly from original research papers and military documentation, ensuring formula accuracy to the highest standard.
- Caliper Measurement Workflows.
Guided site‑by‑site skinfold caliper flow with anatomical diagrams, unit selection, and data validation to ensure repeatable pinches and consistent measurement technique.
- App Store Optimization.
Carefully crafted app store presence with optimized listings on both the Apple App Store and Google Play Store, including localized descriptions and screenshots.
- Professional methods
- 9
- Accuracy (PRO)
- ±3–4%
- Lifetime conversion rate
- 10.3%
- App rating
- ★★★★★
Stats reflect App Store Connect lifetime metrics unless noted otherwise. Valid as of August 2025.
Key Features
- Complex Mathematical Implementation.
Successfully implemented nine peer-reviewed scientific formulas with age-specific coefficients and gender-adjusted calculations, maintaining precision up to 2 decimal places.
- Caliper Guidance & Repeatability.
In‑app guidance for proper skinfold caliper technique, site mapping, unit selection (mm/in), and averaging of multiple pinches to improve measurement repeatability and reduce user error.
- Cross-Platform Architecture.
Built with React Native and Expo, delivering a native experience on both iOS and Android while maintaining a single TypeScript codebase with 100% code sharing.
- Comprehensive Testing.
Over 200 automated tests verify formula accuracy against research papers, handle edge cases, and ensure calculations remain precise across all supported methods.
- Seamless Monetization.
Integrated RevenueCat for robust in-app purchases with family sharing support, offline functionality, and cross-platform purchase sync.