A dynamometer measures how much force you’re producing, displayed either on an analog dial with a needle or on a digital LCD screen. Reading one correctly comes down to understanding the scale, using the peak-hold feature, and knowing what the numbers actually mean for your strength level. Here’s how to do all three.
Analog vs. Digital Displays
Most dynamometers fall into two categories: analog (dial-and-needle) and digital (LCD screen). The type you’re using determines how you’ll take your reading.
Analog dynamometers, like the widely used Jamar, have a round dial face with two scales printed on it. One scale reads in kilograms, the other in pounds. The numbers climb from zero at the bottom and wrap around the dial. When you squeeze or pull, a needle sweeps clockwise to show your force output. On most Jamar-style devices, the kilogram scale is marked in increments of 2 kg, which means you’ll sometimes need to estimate if the needle lands between two markings.
Digital dynamometers display your result on an LCD screen, typically to one decimal place (for example, 34.6 kg). There’s no estimation involved. You simply read the number after the test. Most digital units also let you toggle between kilograms and pounds with a button press.
How the Peak-Hold Needle Works
On analog dynamometers, there’s a second needle, usually red, called the peak-hold needle. This is the key to getting an accurate reading. When you squeeze, the main gauge needle moves with your force in real time, but the red peak-hold needle stays behind at the highest point the gauge needle reached. This lets you read your maximum force after you’ve relaxed your grip, without needing someone to watch the dial during the squeeze.
Before each test, reset the red needle to zero by turning the peak-hold knob counterclockwise. Both needles should line up at zero. If the red needle doesn’t return smoothly or feels like it’s sticking, the device may need servicing. After each squeeze, read the number where the red needle stopped. That’s your peak force for that trial. Then reset it to zero before the next attempt.
Digital dynamometers handle this automatically. The screen locks onto your peak reading and holds it until you press a reset or clear button.
Reading a Hand Grip Dynamometer
Hand grip dynamometers are the most common type. The dial typically ranges from 0 to about 90 kg (200 lb). To get an accurate and comparable reading, your body position matters. The standard protocol from the American Society of Hand Therapists calls for sitting in a chair with your feet flat on the floor, your elbow bent to 90 degrees, and your forearm in a neutral position (thumb pointing up, not rotated inward or outward). Your wrist should be slightly extended, tilted back about 15 to 30 degrees.
Most Jamar-style dynamometers have five handle positions that adjust the width of the grip. Position 2 (the second-narrowest setting) produces the highest force reading for about 70% of people and is the standard setting used in clinical testing. If you’re comparing your results to published norms, use position 2 unless you’ve been specifically instructed otherwise. The average difference between position 2 and a person’s true best position is less than 1 kg.
Squeeze as hard as you can for about 3 seconds, then relax. Read the red peak-hold needle (or the digital display). Do three trials on each hand, resting about 30 seconds between attempts. Your result is typically reported as either the average of those three trials or the single highest value. Both methods are considered reliable, with no meaningful difference in consistency between them.
Reading a Back-Leg-Chest Dynamometer
Back-leg-chest dynamometers are larger devices with a platform you stand on and a handle connected by a chain. The dial is bigger, ranging from 0 to 300 kg (660 lb), with markings in 10 kg or 10 lb increments. You read it the same way as a hand grip dial: find where the needle or peak-hold indicator stopped and match it to the nearest marking on the scale.
Before testing, the chain length is adjusted so the handle sits at about knee height. For a back strength test, you stand on the platform with your knees and hips slightly bent (roughly 135 to 145 degrees at the knee), maintain a natural curve in your lower back, and pull the handle straight up using your back and leg muscles. The contraction lasts about 3 seconds, and you perform 3 repetitions with 30 seconds of rest between each. Your reading is recorded in kilograms of force.
Because the scale increments are larger on these devices (every 10 kg rather than every 2 kg), pay attention to the smaller tick marks between the major numbers. Each small tick typically represents 2 or 5 kg depending on the model. Check your specific dial before testing so you know exactly what each marking represents.
What Your Numbers Mean
A raw number on the dial doesn’t tell you much without context. Grip strength norms vary significantly by age and sex. Based on international data covering over 2.4 million adults across 69 countries, here are the median (50th percentile) grip strength values in kilograms:
- Men aged 20 to 24: 48.0 kg
- Men aged 50 to 54: 46.2 kg
- Men aged 80 to 84: 32.3 kg
- Women aged 20 to 24: 28.6 kg
- Women aged 50 to 54: 28.2 kg
- Women aged 80 to 84: 20.4 kg
If your reading is in pounds and you want to compare to these norms, divide by 2.2 to convert to kilograms.
Clinically, grip strength below certain thresholds can signal low muscle mass, a condition called sarcopenia. The European Working Group on Sarcopenia uses cutoffs of 27 kg or less for men and 16 kg or less for women as indicators of probable sarcopenia. These aren’t diagnostic on their own, but they’re the numbers that typically prompt further evaluation.
Common Reading Mistakes
The most frequent errors aren’t about misreading the dial. They come from inconsistent technique that skews the number before you ever look at it. Holding your arm away from your body, extending your elbow, or rotating your wrist all change the force your muscles can produce, making your reading artificially high or low compared to standardized norms.
On analog devices, parallax is another issue. If you look at the dial from an angle rather than straight on, the needle appears to point at a different number. Always read the dial face-on. And always confirm the red peak-hold needle was reset to zero before each trial. If it was left at 15 kg from a previous test, your next reading will appear to be at least 15 kg regardless of actual effort.
For digital devices, check which unit is displayed before recording. Accidentally writing down a pounds reading as kilograms (or vice versa) is a surprisingly common mistake that makes your result look dramatically different from reality.