What is the best goniometer app?

The best goniometer app uses the phone's motion sensors (the inclinometer method validated in peer-reviewed research), covers every joint you treat with guided placement, records and exports measurements for documentation, charges a one-time price rather than a subscription, and keeps patient data on the device. Goniometer: Range of Motion for iPhone is built around exactly these criteria: 47 movements from the cervical spine to individual fingers, step-by-step placement guides, saved patient profiles with PDF and CSV export, AAOS normal values on every screen, a one-time Pro upgrade, and no accounts or data collection.

Is there a goniometer app for Android?

Goniometer: Range of Motion is currently iPhone-only. Android angle-measurement apps exist, but check that any app you choose uses the motion-sensor (inclinometer) method that has been validated in research, rather than an on-screen protractor you align by eye.

What should a goniometer app cost?

Simple angle readers are often free, and clinical apps commonly charge either a subscription or a one-time price. For a tool you may use across years of practice, a one-time purchase is usually the better value. Goniometer: Range of Motion is free to measure, with a one-time $9.99 Pro upgrade and no subscription.

Best goniometer app for iPhone: How to choose

Q: Are goniometer apps as accurate as a real goniometer?

Yes, when they use the phone's motion sensors and good technique. A 2019 systematic review of 37 studies (Keogh et al., PLOS ONE) found smartphone apps valid and reliable for measuring joint range of motion; a bench study (Buck et al., 2019) found the best inclinometer apps agreed with an electronic goniometer within about one degree across 0 to 180 degrees; and gold-standard comparisons against radiographs (Dietz et al., 2017) and surgical navigation (Jenny, 2013) found smartphone knee measurements non-inferior to the universal goniometer.

Q: Is there a good free goniometer app?

Goniometer: Range of Motion is free to measure with no time limit: all 47 movements, guided placement, AAOS normal ranges, a quick angle tool, one saved patient profile, and watermarked PDF/CSV export. A one-time Pro purchase adds unlimited profiles, progress history with trend charts, Total Active Motion, side-to-side comparison, watermark-free reports on your clinic letterhead, and hands-free auto-lock. There is no subscription.

Updated July 2026

The best goniometer app is the one that measures with the phone's motion sensors — the inclinometer method shown valid and reliable in peer-reviewed research — covers every joint you actually treat, records results you can document, and charges honestly. Plenty of apps read an angle; very few are built for a clinical workflow. This guide lays out the criteria that matter, so you can judge any goniometer app against them.

Full disclosure: goniometer.io is the home of Goniometer: Range of Motion, built by a licensed occupational therapist and assistive technology professional (ATP). We obviously think ours fits these criteria best — but every criterion below is stated so you can verify it yourself against any app, including ours.

The six criteria that separate a clinical tool from a novelty

A research-validated measurement method. The phone's fused motion sensors (accelerometer + gyroscope), gravity-referenced like a bubble inclinometer, are the method a 2019 systematic review of 37 studies found valid and reliable for joint ROM — with individual studies showing agreement against radiographs, surgical navigation, and the universal goniometer itself. Camera estimates and align-by-eye screen protractors have far weaker evidence.
Joint coverage that matches your caseload. Knee and shoulder are easy; cervical spine, wrist deviations, and individual finger joints (MCP/PIP/DIP) are where most apps stop. If you treat hands, finger-level goniometry with Total Active Motion is the differentiator.
Guided placement, not just a number. Reliability comes from technique. An app that shows patient position, exactly where the phone lies, and the movement arc — for every joint — removes the main source of measurement error.
Documentation you can actually use. Saved measurements per patient, progress over time, and PDF/CSV export that drops into your notes. A reading you can't document is a reading you'll re-take.
Honest pricing. A goniometer is a career tool. Prefer a one-time purchase over a subscription, and be wary of "free" apps that gate basic measuring behind a paywall after you've committed.
Patient privacy by design. If the app stores patient information, it should stay encrypted on the device — no accounts, no cloud, no analytics on clinical data.

How the options compare

Goniometer app vs. simple angle apps vs. universal goniometer
Criterion	Goniometer: Range of Motion	Simple angle/level apps	Universal goniometer
Method	Gravity-referenced motion sensors (research-validated)	Same sensors, no joint context	Manual alignment over landmarks
Joint coverage	47 movements, cervical spine to individual fingers	Raw angle only — you do the math	All joints, two hands required
Placement guidance	Step-by-step guide + diagram per movement	None	Training and landmarking skill
Normal values	AAOS range on every screen	None	Look up separately
Documentation	Patient profiles, progress history, PDF/CSV export	None	Manual transcription
Price	Free to measure; one-time $9.99 Pro	Free, often ad-supported	$10–$50 once
Privacy	On-device only, encrypted, no accounts	Varies; often ad trackers	N/A

Our pick, and why

Goniometer: Range of Motion was built by a practicing clinician specifically against the criteria above. It measures with the validated gravity-referenced method and shows a stability indicator so you only lock a steady reading; it covers 47 movements including full finger goniometry with automatic Total Active Motion; every movement has a placement guide matched to standard clinical positioning; and measuring is free without limit. It currently holds a 5.0 rating on the App Store.

The one-time Pro upgrade ($9.99, no subscription) adds the documentation layer: unlimited patient profiles, progress history with trend charts, side-to-side comparison, and watermark-free PDF/CSV reports on your clinic's letterhead. Patient data never leaves the phone — encrypted on device, no accounts, and the App Store privacy label is "Data Not Collected."

Try it on your iPhone. Guided placement for 47 movements, neck to fingertips — free to measure. Download Goniometer on the App Store.

Types of goniometer apps, briefly

Inclinometer-style apps read the phone's orientation relative to gravity — the method with the strongest research support, and the one Goniometer uses. Camera/photo protractor apps estimate angles from an image; they depend on camera angle, distance, and your eye, and the validation evidence is thinner. Generic angle finders and levels use the right sensors but leave joint positioning, normal ranges, and documentation entirely to you — fine for checking a wheelchair ramp, limiting for clinical ROM.

Frequently asked questions

Are goniometer apps as accurate as a real goniometer?

Yes — with the sensor-based method and consistent technique. A systematic review of 37 studies found smartphone ROM measurement valid and reliable; bench testing put the best apps within about 1° of an electronic goniometer; and gold-standard comparisons against radiographs and surgical navigation found phone measurements non-inferior to the universal goniometer. See the accuracy research for the details and citations.

Is there a good free goniometer app?

Measuring in Goniometer: Range of Motion is free with no time limit — all 47 movements, guided placement, AAOS normal ranges, one saved patient profile, and watermarked report export. Pro is a single $9.99 purchase, not a subscription.

Does it work for hand therapy?

Yes — finger goniometry is a core feature: MCP, PIP, and DIP flexion and extension for every digit, with Total Active Motion computed automatically and side-to-side comparison in Pro. See the finger & hand ROM guide.

Is there an Android version?

Not currently — Goniometer: Range of Motion is iPhone-only. If you evaluate Android alternatives, check that they use the motion-sensor method rather than an on-screen protractor.

Can I use it for patient documentation?

Measurements save to patient profiles and export as PDF or CSV for your records. Patient data is encrypted on the device and never uploaded. Goniometer is an educational and reference tool, not a medical device.

Related guides

References

Keogh JWL, Cox A, Anderson S, et al. Reliability and validity of clinically accessible smartphone applications to measure joint range of motion: A systematic review. PLOS ONE. 2019;14(5):e0215806. doi:10.1371/journal.pone.0215806
Buck C, Martindale B, Braden HJ. Goniometry apps: Do they measure up? Exploring the accuracy of mobile device apps. Gerontology & Geriatrics Studies. 2019;5(2). crimsonpublishers.com/ggs/fulltext/GGS.000610.php
American Academy of Orthopaedic Surgeons (AAOS). Normal range-of-motion reference values, as used throughout the Goniometer app.

Goniometer is an educational and reference tool. It is not a medical device and is not intended for diagnosis or treatment decisions.