Measure your body fat with clinical precision.
Skinfold protocols and validated formulas, in your pocket. No account, no internet required.
Trusted by health & fitness professionals worldwide
Spreadsheets and tape measures aren't enough.
Clinical body composition deserves clinical tooling — without the friction of a desktop suite.
Manual math is slow and error-prone
Switching between calipers, calculator and notebook is a recipe for inconsistent results.
Generic apps lack scientific rigour
Most fitness apps use a single formula and skip the protocol that actually fits your client.
No memory means no progress
Without a clean history, you can't show clients how far they've come — and they won't stay.
Plixi is built for clinical workflows.
Validated formulas, multi-patient memory, visual progress, fully offline. Designed by a clinician, used by thousands.
Everything you need for body composition analysis
Designed for accuracy, efficiency and a frictionless workflow on phone and tablet.
Validated formulas
3, 4 and 7-site protocols with Durnin/Womersley, Jackson/Pollock, Siri, Brozek and Behnke equations.
Patient management
Custom fields, complete history and visual progress charts for every client.
Personal & Professional modes
Switch the entire interface between self-tracking and multi-patient workflow.
Offline-first & private
Calculations and patient data live on your device. No account, no cloud, no leaks.
Built for tablets
Side-by-side panels and dense data layout that respect your iPad's screen real estate.
Shareable progress
Visual reports your clients understand at a glance — perfect for monthly check-ins.
Precise results in seconds
Pick a 3, 4 or 7-site protocol and let Plixi run the right formula automatically. Body density via Durnin/Womersley or Jackson/Pollock, body fat % through Siri, Brozek or Behnke.
- Automatic formula selection by protocol
- Real-time results as you enter measurements
- Detailed breakdown of density and fat percentage
See progress at a glance
Track changes over time with interactive charts. Compare measurements side by side, spot trends and share visual reports with your clients.
- Interactive progress charts over time
- Side-by-side measurement comparison
- Complete history and trend analysis
Your way, your mode
Personal mode for self-tracking, Professional mode for multi-patient workflows. Each mode adapts the UI, features and data flow to how you actually work.
- Personal mode for individual tracking
- Professional mode for unlimited patients
- Adaptive interface based on your role
Optimized for every screen
Not stretched — truly redesigned. Plixi adapts to take full advantage of tablet screens, surfacing more data with less tapping.
Built on validated, peer-reviewed formulas
Plixi implements the protocols and equations the literature actually supports — not a guess wrapped in a fitness app.
All equations are applied automatically based on the protocol you choose. Plixi does not invent new formulas — it implements the established ones correctly.
Trusted by health professionals
What fitness coaches, nutritionists and clinicians say about Plixi.
“It's extremely rare to find a free app that doesn't ask for any personal information, no create an account and no bombardment of annoying ads just for a simple calculation. It's a very minimalistic app but it speaks volume. Worth the download.”
“Excellent calculator with all options available. Love that you can save clients results! Recommended.”
“The app is simple and has a good selection of measurement methods. Had the ability to save data for multiple users.”
Start free. Upgrade when you need more.
Download Plixi free and try every formula with 1 patient profile and up to 3 measurements. Upgrade to Pro to unlock unlimited patients, unlimited measurements and the full pro toolkit.
Free
- All validated formulas and protocols
- 1 patient profile
- Up to 3 saved measurements
- Offline-first, no account
Pro
Pro- Unlimited patients and measurements
- Progress charts and full history
- Custom fields, photo gallery, export & share
- Ad-free, priority support
Frequently asked questions
Everything you need to know about Plixi and body composition analysis.
Ready to upgrade your body composition workflow?
Join thousands of professionals using Plixi to deliver accurate, repeatable measurements.
Free • iOS and Android
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