For decades, the Jamar® Hand Dynamometer has been one of the most recognizable tools in occupational therapy, physical therapy, hand therapy, and rehabilitation. Clinicians have used Jamar dynamometers to measure grip strength, establish baselines, monitor progress, and document functional changes.

Today, clinicians have more than one way to use the Jamar name. The traditional Jamar Hydraulic Hand Dynamometer continues to be a familiar standard in rehabilitation settings, while the Jamar Digital Hand Dynamometers, including the Jamar Plus+ and Jamar Smart, offer electronic measurement and automated calculations.

So which one is better?

The answer depends on what you need from your hand dynamometer.

A Brief History of the Jamar Dynamometer

The story of the Jamar begins in the 1950s. The device was developed through the work of orthopedic surgeon Charles O. Bechtol, physical therapist Hyman Jampol, engineer Morris Asimow, and machinist Robert Reiss. According to an account published in Clinics in Orthopedic Surgery, the name “Jamar” was derived from the names of the three principal developers: JAMpol, Asimow, and Reiss. A Jamar dynamometer was described in published work as early as 1953, with Bechtol's influential work appearing in 1954.

The original concept was remarkably straightforward: create an adjustable handgrip that could measure isometric grip force using a sealed hydraulic system.

That basic design proved to be incredibly useful.

Over the following decades, the Jamar Hydraulic Hand Dynamometer became widely used in clinical practice and research. Its five adjustable handle positions, peak-hold needle, dual pound/kilogram scale, and relatively simple operation made it practical for everyday clinical use.

Perhaps more importantly, a tremendous amount of grip-strength research was conducted using the Jamar Hydraulic Hand Dynamometer.

This history matters when interpreting grip-strength results. The Jamar Hydraulic has been described in the research literature as the “gold standard” for grip-strength measurement, in large part because of its established reliability and the availability of normative data.

That doesn't necessarily mean the hydraulic Jamar is the only good choice today. It means that clinicians have decades of experience and research behind this particular method of testing.

The Jamar Hydraulic Hand Dynamometer

The traditional Jamar Hydraulic Hand Dynamometer uses a sealed hydraulic system to measure grip force. As the patient squeezes the handle, the force is transmitted through the hydraulic system to the gauge.

The peak-hold needle remains at the patient's maximum reading until it is reset.

The handle can be adjusted to different positions to accommodate different hand sizes and testing protocols.

Pros of the Hydraulic Jamar

Established clinical history

This is probably the biggest advantage of the hydraulic Jamar. It has been used for decades, and a large body of clinical and research literature is associated with Jamar grip-strength testing.

Familiar to therapists

Many OTs, PTs, CHTs, physicians, and rehabilitation professionals learned to perform grip-strength testing using a hydraulic Jamar. That familiarity can make testing quick and intuitive.

Simple operation

There are no batteries, apps, menus, or electronic settings to navigate. Adjust the handle, position the patient, instruct the patient to squeeze, record the reading, and reset.

Excellent for basic grip-strength testing

If your primary need is to obtain a maximum grip-strength measurement and document it in the patient's chart, the hydraulic Jamar does exactly that.

A long history of normative data

Many commonly referenced grip-strength norms were developed using Jamar or Jamar-type hydraulic dynamometry. This is an important consideration when comparing a patient's results with published data.

Cons of the Hydraulic Jamar

The clinician has to record and calculate the results

If you perform three trials on each hand, someone has to write down the individual results and calculate the average or other statistics.

That isn't difficult—but it takes time, and manual calculations create an opportunity for transcription or mathematical errors.

The analog gauge requires the clinician to read the result

The clinician must watch the gauge and correctly identify the peak reading.

Hydraulic components require maintenance

Like other hydraulic instruments, the device can potentially develop problems associated with its hydraulic system. Calibration should also be checked periodically, particularly if the instrument has been dropped or there is reason to question its accuracy.

Less convenient for more complex testing protocols

The traditional Jamar is excellent at what it was designed to do. However, if you want automated averages, standard deviations, coefficient of variation, rapid-exchange testing, graphs, or electronic records, you'll be doing more of that work yourself.

Jamar Digital Hand Dynamometers

Digital Jamar models take the familiar Jamar concept and replace the hydraulic measurement system with electronic load-cell technology.

The Jamar Smart and Jamar Plus+ Digital Hand Dynamometers measure grip force electronically rather than hydraulically. Both are designed around the same basic purpose as the traditional Jamar: measuring isometric grip strength.

The biggest difference is what happens after the patient squeezes the handle.

Instead of reading an analog gauge and manually recording the results, the digital unit displays the measurement electronically and can automatically perform calculations.

Jamar Plus+ vs. Jamar Smart

There are two important Jamar digital options to understand.

Jamar Plus+ Digital Hand Dynamometer

The Jamar Plus+ is essentially a digital, standalone version of the Jamar concept.

It uses electronic load cells, has a digital LCD display, and automatically calculates statistics such as average, standard deviation, and coefficient of variation.

It does not provide the wireless tablet connectivity of the Jamar Smart.

For clinicians who want digital measurements and automatic calculations without necessarily needing an app, this can be an appealing middle ground.

Jamar Smart Hand Dynamometer

The Jamar Smart takes the digital concept another step further.

In addition to its onboard display and automatic calculations, it can communicate wirelessly with a mobile device through the Jamar Smart app. Depending on the software configuration, clinicians can record, save, graph, and track grip-strength results.

The Smart also supports multiple testing protocols, including standard grip testing and rapid-exchange testing. Up to five trials can be conducted on each hand without resetting between trials, with average, standard deviation, and coefficient of variation calculated automatically.

Pros of a Digital Jamar

Automatic calculations

This is one of the biggest advantages.

The digital Jamar can automatically calculate the average, standard deviation, and coefficient of variation. That eliminates the need to pull out a calculator after every grip-strength assessment and reduces opportunities for calculation errors.

Easy-to-read digital display

The LCD display provides a clear numerical reading rather than requiring the clinician to interpret an analog needle.

No hydraulic oil

Because the digital models use electronic load cells rather than a hydraulic system, there is no hydraulic fluid to leak.

More efficient testing

For clinics that perform large numbers of grip-strength evaluations, automatic calculations and electronic test protocols can save time.

Additional testing capabilities

The Jamar Smart can support several testing protocols, including rapid-exchange testing. The accompanying app can also provide graphing and record-keeping capabilities.

Useful for documentation

Digital results can make it easier to document changes over time, particularly when using the Smart with its app.

Cons of a Digital Jamar

More technology means more things to manage

The simplicity of the hydraulic Jamar is also one of its strengths.

With a digital model, you have batteries, electronic components, and—if you're using the Smart—an app and compatible mobile device.

Higher technology dependence

A hydraulic Jamar doesn't need to be paired with a tablet or connected to an app to perform a grip-strength test.

For some clinicians, that simplicity is preferable.

Cost

Digital Jamar models can cost more than a traditional hydraulic model, depending on the specific model and current pricing.

Different devices should not automatically be treated as interchangeable

This is an important consideration for clinicians and researchers.

Even when two dynamometers are both designed to measure grip strength, measurements can vary between devices. Research has demonstrated differences between hydraulic and digital dynamometers, emphasizing the importance of consistency when comparing measurements over time.

If you're following a patient longitudinally, switching instruments in the middle of a treatment episode may make the results more difficult to interpret.

Hydraulic vs. Digital: At a Glance

Feature	Jamar Hydraulic	Jamar Plus+ Digital	Jamar Smart Digital
Established clinical history	★★★★★	★★★★☆	★★★★☆
Simple operation	★★★★★	★★★★☆	★★★☆☆
No batteries required	✓
Digital readout		✓	✓
Automatic calculations		✓	✓
Hydraulic system	✓
Electronic load cells		✓	✓
Wireless/app capability			✓
Graphing/data storage	Manual	Limited	✓
Rapid-exchange testing	Manual	Supported	Supported
Extensive historical research	★★★★★	★★★☆☆	★★★☆☆

Features can vary by specific model and software version. Always consult the current manufacturer's specifications before purchasing.

So, Which Jamar Should You Choose?

There isn't one answer that is right for every clinician.

Choose the Hydraulic Jamar if:

• You want the traditional Jamar design.
• You value its long history in clinical practice and research.
• You primarily need straightforward grip-strength measurements.
• You don't mind recording and calculating results manually.
• You prefer equipment that doesn't require batteries or software.
• Your practice, research protocol, or facility already uses hydraulic Jamar equipment.

Consider the Jamar Plus+ if:

• You want the familiar Jamar approach with digital measurement.
• You want automatic calculations.
• You prefer a digital display.
• You want to eliminate the hydraulic system.
• You don't need wireless tablet connectivity.

Consider the Jamar Smart if:

• You perform frequent grip-strength evaluations.
• You want automatic calculations.
• You want additional testing protocols.
• You want to graph and track results electronically.
• You want the option of connecting your dynamometer to a tablet.

The Bottom Line

The Jamar Hydraulic Hand Dynamometer has earned its reputation over decades of clinical use and research. Its simple design, reliability, and enormous history in rehabilitation make it a tool that is still highly relevant today.

Digital Jamar models don't necessarily make the hydraulic Jamar obsolete. Instead, they address some of the limitations of an analog instrument by adding electronic measurement, automatic calculations, additional testing options, and—in the case of the Jamar Smart—digital data management.

For a clinician who wants simplicity and a long-established testing method, the hydraulic Jamar remains an excellent choice.

For a clinician who wants automation, efficiency, and digital documentation, a Jamar digital model may be worth the investment.

And perhaps the most important consideration of all is consistency: whichever dynamometer you choose, use a standardized testing position, handle setting, patient instructions, and testing protocol. Consistency is what allows grip-strength measurements to become meaningful clinical information rather than simply a number on a gauge.

Whether you're outfitting a new therapy clinic, replacing an old dynamometer, or deciding whether it's time to make the switch from hydraulic to digital, understanding the strengths and limitations of each version can help you choose the Jamar that best fits your practice.