A goniometer, pronounced (gō'nē-om'ĕ-tĕr), is an instrument used to measure angles, particularly range of motion angles of a joint. The origins of the word goniometer is Greek - gonia means angle and metron means measure. Goniometers have been used since 1780. They measure range of motion, determine direction, and measure an object’s dimensions and they are a fairly simple design.
Used frequently in physical therapy, goniometers are generally clear plastic, but you can find metal ones and most read both inches and centimeters, usually in one degree increments, but can be in any increment from 1 to 10. Goniometers are used for flexion and extension, abduction and adduction, and also for rotation in the neck, elbow, wrist, shoulder, and spine.
Goniometric stage is another name for a goniometer. Goniometers are like linear stages. Linear stages partially rotate around a fixed point above the mounting surface. There are different sizes of goniometers to measure range of motion. For joints like hips and knees, there are larger sizes. For joints like fingers and hands, smaller sizes are available. Goniometers have two “arms” - a stationary arm and a moveable one - and a fulcrum with hash marks on the center to read precise measurements.
A bubble inclinometer has a 360 rotating dial and scale with fluid indicator and are generally used for measuring the hip, knee, elbow, and shoulder. There is also a laser goniometer used to measure the sharpened angle of a knife blade. It works by reflecting a low powered laser beam from the facets of a cutting edge.
The most universal is the traditional goniometer, which consists of three parts. The body of a traditional goniometer is designed like a protractor with a measuring scale around the body. On the half circle model, the scale extends from 0º to 180º and 180º to 0º. One the full circle models, the scale measures from 0º to 360º and 360º to 0º. The other two features of the traditional goniometer are the stationary and moving arms. The stationary arm is just that - it does not move independently of the body. The moving arm attaches to the fulcrum with a rivet or screw-like device allowing the arm to move on the body.
Comparison Chart for the Best Goniometers
|Medigauge||Digital||+/- 0.5°||Full 360°||$$$|
|Elite Medical Instruments||Manual||+/- 1°||Full 360°||$$|
|Elite Medical Instruments||Manual||+/- 1°||Full 360° & 180°||$$|
|Every Ready||Manual||+/- 1°||Full 360°||$|
|Prestige||Manual||+/- 1°||Full 360°||$|
|Complete Medical||Manual||+/- 1°||Full 360°||$|
How to use a Goniometer
- Place the goniometer over the fulcrum of the joint.
- Place the stationary arm of the goniometer along the stationary line of the body and the movable arm on the moving part of the body.
- Move the joint in the desired direction to the fullest extent of motion, following the movement with the movable arm of the goniometer. Make sure the stationary arm stays straight.
- Stabilize the stationary part of the body. This is the part of the body that is proximal (closer to the midline of the body) to the joint you are testing. It is important that not to move the body while moving the joint; this step isolates the joint movement for a more accurate measurement.
- Look at the reading on the goniometer before removing it. Make sure that you take an accurate reading of the degree of motion on the goniometer, and that you consistently use the same stationary and movable landmarks when measuring, to ensure consistency. Be sure to record the range of motion for the joint.
What to look for in a good goniometer
If your purpose for purchasing a goniometer is for joint flexibility, your selection will generally be dictated by the joint angle you are measuring. There are many different goniometer arm lengths, and each is geared for a different joint. Longer arm lengths are needed when measuring bigger joints, like hips, knees, elbows, and shoulders. Shorter instruments are needed for measuring smaller joints like fingers, ankles, and wrists.
Aside from the arm length, you should pay attention to construction. You want to be sure the fulcrum is sturdy and doesn’t have too much give, so it doesn’t slip out of place while measuring. And you want to be sure you have a goniometer made of a sturdy, but slightly flexible plastic or metal. Transparent plastic is somewhat helpful for reading the hash marks clearly.
- Proper length for joint
- Measurements at least 1 degree increments
- Sturdy fulcrum
- Constructed in plastic or metal
Best Digital and Manual Goniometers
1. Medigauge Electronic Digital Goniometer for Orthopaedics, Orthopedics, Chiropractic, Sports Medicine, Animal Science, Occupational Therapy OT, Physical Therapy PT, Research
- Dual 10 inch/250 mm blades with center line and inch and metric graduations
- Transparent poly fiber blades permit easy location of joint axis and unobstructed observation of movement
- Latex free and hypoallergenic poly fiber blades are easily sanitized after use
- Measuring range: full 360° when rotated in either direction
- Accuracy: +/- 0.5° (half of one degree)
- Battery: 3 volt CR 2032 installed with extra included
- Battery life: typical use approx. 1 year
The Medigauge Electronic Digital Goniometer is designed by therapists for therapists. Containing dual 10 inch or 250 mm poly fiber blades with a centerline and English metric graduations, it is one of the most reliable digital goniometers on the market. This goniometer is not only useful to physical and occupational therapist, but also aids anyone in animal science, sports medicine, orthopedics, and even for performing research.
The Medigauge digital goniometer is easy to learn and use, and gives you highly accurate, repeatable and reliable joint measurements. From the “zero” setting it measures 360° in both directions. Relative “zero” can be set at any point in the arc. Degrees re displayed in .05 degree increments (5 hundredths of degree) and has an accuracy of +/-.5 degrees (half of a degree). The transparent poly fiber blades make it easy to locate the joint axis and gives you an unobstructed observation of movement, and the hypoallergenic blades are easily sanitized after each use.
Compact and lightweight, the Medigauge digital goniometer has a large LCD screen that displays continuously while the blades are adjusted. The “hold” function keeps you from forgetting a measurement. WIth normal use, the 3V lithium ion battery will last one year. To help save the battery life, the unit powers down after five minutes of nonuse. With your purchase, the Medigague goniometer comes with one battery already installed and one extra battery.
- Highly accurate measurements
- Easy to use read
- Large for smaller joints
- Adult size only
2. EMI Goniometer 3 Piece Set 12" , 8" , 8" Spinal: 3 Pieces
- 360° coverage in 1 degree increments
- 12” Goniometer
- 8” Goniometer
- 8” Spinal goniometer
- Clear plastic
- Large numbers
The EMI Goniometer 3 piece set comes with a 12” goniometer, an 8” goniometer, and an 8” spinal goniometer. Designed to measure range of motion, it is perfect for physical therapy professionals and students or even just for your personal use. You’ll get 360° coverage in 1 degree increments to measure joint angles and also to compare the changes in the joint angles.
All three goniometers are made of clear, durable plastic with large, easy to read numbers. The clear plastic makes it easy to observe the joint’s axis of motion and range of motion. Located on the arm of the device, the large numbers measure in both inches and centimeters. Ensuring International STandards of Measurement accuracy, the head of all three goniometers measure in one degree increments.
- No batteries
- 2 different goniometer sizes
- Durable, flexible plastic
- 8” Goniometer has an arrow that obscures reading
- 8” Goniometer less sturdy than 12”
3. EMI Pocket 3 Piece Goniometer Set: Finger Goniometer, 6" Goniometer, 180 Degree 6" Goniometer
- 1 Finger goniometer
- 6” Round goniometer
- 180° 6” Goniometer
- Plastic flexion-hyper extension
- Conforms to ISOM standards
The EMI Goniometer 3 piece set comes with a finger goniometer, 6” round goniometer, and a 180° 6” protractor goniometer. All are made of durable, clear plastic and have large numbers making it easy to read. They all also have a five inch linear scale calibrated in both inches and centimeters that conform to ISOM standards. Ideal for any clinic, physical therapist, medical professional, healthcare facility, it is also suited for use as a resource to measure recovery right after injuries.
Plastic flexion-hyper extension clear plastic finger goniometer attributes and simple to read scale, markings for up to 20 degrees hyperextension and a hundred and twenty degrees of flexion.
The 6” protractor goniometer is designed to clearly measure a patient’s joint’s variety of movement. It has 180° coverage to measure joint angles and compare any changes in joint angles. Translucent plastic allows for easy observation of joint’s axis of motion, and its range of motion. One arm has a linear scale in inches and centimeters. Scale reads 1° increments.
The 6" protractor goniometer is used to measure the patient's range of motion and features a full 360 degree range in single degree increments. With large text and easily readable, it is perfect for your physical therapy needs.
- Set includes a variety of sizes
- Small size
4. Ever Ready Plastic 12" Goniometer 360 Degree
- 360 degree head
- 3 scales calibrated to be used with the ISOM system
- Scale reads 1 degree increments
- Clear plastic
- Measurements in inches and centimeters
The EverReady First Aid 12” goniometer with 360 degree coverage in one degree increments to ensure ISOM accuracy. The head and both arms of the goniometer have inch and centimeter measurements. Clear plastic permits observation of joint’s range of motion and axis of motion.
Use this goniometer to measure the flexibility of a joint, which is important for injury prevention and execution of many sporting movements. A goniometer is often used in patients who have limitations of movement due to muscle tightness, joint stiffness or other conditions affecting their joint range of motion. The results of measurement is often written on the "Objective" portion of the physical therapist (PT) notes. It is written as numbers followed by the "degrees" sign. For example, hip flexion 120o.
Measuring range of motion in the joints of the body with the stationary arm, protractor, fulcrum, and movement arm to measure angle from axis of the joint. As measurement results will vary by the degree of resistance, it’s a good idea to record two levels of range of motion results.
- Easy to use and read
- Sturdy construction
5. Prestige Medical Plastic Goniometer 360 Degree
- 360 degree head
- Scale reads 1 degree increments
- Inch and centimeter measurements
- Clear plastic
- 12” Goniometer
The Prestige Medical 12” protractor goniometer is designed to measure the range of motion in anyone’s joints. It’ made of clear, heavy-gauge lexan plastic for durability and has large text to make it easy to read axis of motion and range of motion.
Prestige’s goniometer measures a full 360 degree range in single, one degree increments. Inch and centimeter measurements are also printed on the arm. Use this goniometer to measure the range of motion in your knee joint, shoulder, or even hip joint.
Prestige even gives you a guide for gauging angles.
- Durable lexan plastic
- Measurements only on one side
6. Transparent 8" Plastic Goniometer 360 Degree Protractor Style
- 360° sweeping protractor arm
- Transparent plastic
- Calibrated head to 0° to 180°
- Large text
Complete Medical gives you a traditional goniometer you can use for flexion and extension, abduction and adduction. The least expensive model on our list, this instrument has a 360° sweeping protractor arm movement - a linear moving arm with both inch and centimeter measurements. This goniometer head is calibrated to 0° to 180° in 5° increments and has 3 scales calibrated for use with the ISOM system.
Constructed in sturdy plastic with a transparent body for repetitive use and easy body placement.
large, easy to read text and numbers. WIth text and numbers on one side of the instrument only this goniometer may be a little less useful for those needing measurements on both arms. To measure the range of motion at a joint, the center of the goniometer is positioned at the axis of rotation of a joint, and the arms of the goniometer are aligned with the long axis of the bones of the adjacent segments or to an external reference.
- Sturdy, transparent body
- Inch and centimeter measurements
- Numbers on one side only
Aside from the options listed here, there are now apps for your smartphone or other portable device. These devices can measure changes in position using the gyroscopic and accelerometer technology. By placing the phone in the right position on your joint, moving through its available range of motion, the app will measure the amount of motion that just occurred around that joint.
There are even goniometers that measure range of motion while you move - these are generally strapped to your body part. These options are fairly cost prohibitive. A traditional goniometer is usually all you need.
When you’re looking to increase your joint flexibility, you may want to approach your therapeutic recovery methodically. Using a goniometer, you can regularly measure your flexibility to determine whether your rehabilitation program is working. Maybe you need to improve your shoulder joint rotation - the adduction and horizontal adduction. Maybe you need to strengthen the joint flexibility in your fingers. Regardless of which joint you are improving or maintaining the flexibility on, you can keep track of your progress with a goniometer.
Before you begin any physical routine to increase your flexibility, you should always consult a professional. While you can take measurements and track your progress, a professional should be making the decisions on what program will work for your particular issue and joint. Avoiding additional strain or injury should be your goal and your doctor or physical therapist can assist with that.