How to measure elbow range of motion
Clinical guide · Updated July 2026
To measure elbow flexion with a goniometer, position the arm at the side with the forearm supinated, center the fulcrum over the lateral epicondyle of the humerus, align the stationary arm toward the acromion and the moving arm toward the radial styloid, then bend the elbow and read the angle. Normal elbow ROM is about 0° extension to 150° flexion, with 80° of forearm pronation and supination (AAOS). The steps, landmarks, and reliability evidence are below.
Normal elbow range of motion
| Movement | Normal ROM |
|---|---|
| Elbow flexion | 150° |
| Elbow extension | 0° |
| Forearm pronation | 80° |
| Forearm supination | 80° |
See the full normal range of motion chart for every joint. The Goniometer app guides elbow flexion and extension with animated placement.
What you need
- A universal goniometer, digital goniometer, or a smartphone goniometer app.
- A supported position where the upper arm is stable and the forearm is free to move.
- Reference to the landmarks: the lateral epicondyle of the humerus, the acromion process, and the radial styloid.
How to measure elbow flexion, step by step
- Position the patient. Arm at the side with the forearm supinated (palm up) and the elbow straight — this is the 0° starting position.
- Find the landmarks. Locate the lateral epicondyle of the humerus, the acromion process, and the radial styloid.
- Center the fulcrum. Place the goniometer axis over the lateral epicondyle of the humerus.
- Align the arms. Line the stationary arm along the lateral midline of the humerus toward the acromion and the moving arm along the lateral midline of the radius toward the radial styloid.
- Move to end range. Bend the elbow, bringing the hand toward the shoulder, until it stops.
- Read and record. Read the angle at end range and note the side (L/R) and patient position.
Elbow extension
Extension is referenced to the straight arm: a 0° reading is full extension, an elbow that cannot straighten has a flexion contracture (recorded as the degrees short of 0°), and an elbow past neutral is in hyperextension. Forearm pronation and supination (about 80° each) are measured with the elbow flexed to 90° at the side, turning the palm down or up.
Getting a reliable measurement
Elbow goniometry is highly reliable. Rothstein and colleagues, measuring passive elbow and knee motion in a clinical setting, found intratester (same-examiner) reliability of r .91 to .99 and good intertester reliability for elbow flexion and extension. Four habits keep readings repeatable:
- Standardize the position. Support the upper arm the same way each time and keep the forearm supinated.
- Palpate the landmarks each time rather than eyeballing them — landmarking is the biggest source of variation.
- Read at a stable end range, not mid-motion, and to the whole degree.
- Use one examiner for progress tracking. Compare a patient’s elbow to their own earlier measurement, taken the same way.
Measuring elbow ROM with an iPhone
A smartphone goniometer app replaces the two-armed goniometer with the phone’s gravity-referenced motion sensor: lay the phone along the forearm, set zero, and the change in tilt as the elbow bends is the joint angle. Peer-reviewed research finds smartphone measurement valid and reliable for elbow ROM, comparable to a universal goniometer — see the accuracy evidence. A 2018 study found smartphone elbow measurements valid and reliable, with agreement varying by movement (Keijsers et al.).
Measure the elbow on your iPhone. Goniometer shows animated placement for elbow flexion and extension, with the AAOS normal range beside every reading — free to measure. Download Goniometer on the App Store.
Frequently asked questions
What is normal elbow range of motion?
About 0° extension to 150° flexion, with 80° of forearm pronation and 80° of supination, per AAOS.
How do you measure elbow flexion with a goniometer?
With the forearm supinated, center the fulcrum over the lateral epicondyle of the humerus, align the stationary arm toward the acromion and the moving arm toward the radial styloid, bend the elbow, and read the angle.
What landmarks are used to measure the elbow?
The lateral epicondyle of the humerus (axis), the acromion (stationary arm), and the radial styloid (moving arm).
How reliable is elbow goniometry?
Highly reliable: Rothstein et al. reported intratester reliability of r .91 to .99 for elbow flexion and extension. Consistent technique matters most.
Can you measure elbow range of motion with a phone?
Yes — a smartphone goniometer app reads the phone’s motion sensor and has shown validity and reliability comparable to a universal goniometer in peer-reviewed research.
References
- Norkin CC, White DJ. Measurement of Joint Motion: A Guide to Goniometry. 5th ed. Philadelphia: F.A. Davis; 2016.
- American Academy of Orthopaedic Surgeons. Joint Motion: Method of Measuring and Recording. Chicago: AAOS. Normative range-of-motion reference values, as used throughout the Goniometer app.
- Rothstein JM, Miller PJ, Roettger RF. Goniometric reliability in a clinical setting. Elbow and knee measurements. Physical Therapy. 1983;63(10):1611–1615. pubmed.ncbi.nlm.nih.gov/6622536
- Keijsers R, Zwerus EL, van Lith DRM, et al. Validity and reliability of elbow range of motion measurements using digital photographs, movies, and a goniometry smartphone application. Journal of Sports Medicine. 2018;2018:7906875. doi:10.1155/2018/7906875
- 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
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Goniometer is an educational and reference tool. It is not a medical device and is not intended for diagnosis or treatment decisions.