Microamps Explained, What 335, 500 and 680 Really Mean
Medically reviewed by
4 independent reviewers
Andrew Conrad Barile, PT, DPT
Doctor of Physical Therapy (DPT) | Licensed Physical Therapist (PT) | CEO and Founder, Xtreem Pulse LLC
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Dr. Andrew Conrad Barile is a Doctor of Physical Therapy and the CEO and Founder of Xtreem Pulse LLC, the engineering company behind PureLift. He earned his Doctorate in Physical Therapy from Daemen College and is a licensed physical therapist.
He brings over two decades of clinical and entrepreneurial experience across physical therapy, craniosacral therapy and medical device innovation, built on a working knowledge of human anatomy and muscle physiology.
For PureLift LAB he reviews how current is delivered across all ten levels, from sub-sensory nanocurrent and skin-level microcurrent to motor-level EMS, and how the Infuse pass fits into the same ten-minute routine.
Bertica M. Rubio, M.D.
Board-Certified Physician, Dartmouth Medical School | Medical Director, Antiaging Regenerative Medicine Clinic
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Dr. Bertica M. Rubio is a board-certified physician and Medical Director of the Antiaging Regenerative Medicine Clinic in Redlands, California. She earned her Doctor of Medicine from Dartmouth Medical School and completed her pediatrics residency at UC Irvine Medical Center.
With decades of clinical experience, she specialises in age management medicine, regenerative medicine, wound healing and growth factor therapies, and her practice integrates evidence-based medical science with advanced aesthetic treatment.
For PureLift LAB she reviews articles for medical accuracy across the whole dial, from the gentle nanocurrent and microcurrent settings through to muscle-level EMS and the Infuse pass.
Daniel Grinberg, MD, FACS
Board-Certified Otolaryngologist | Head and Neck Surgeon | Fellow, American College of Surgeons | Mount Sinai
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Daniel Grinberg, MD, FACS is a board-certified otolaryngologist and head and neck surgeon at ENT and Allergy Associates in West Nyack, New York. He earned his medical degree from Columbia University College of Physicians and Surgeons.
He completed his otolaryngology residency at New York University Medical Center, serves as Assistant Clinical Professor at Mount Sinai School of Medicine, and is a Fellow of both the American College of Surgeons and the American Academy of Otolaryngology.
For PureLift LAB he brings a wider clinical lens, connecting at-home facial stimulation from microcurrent to EMS to the anatomy underneath, with the same rigour we apply to every device specification.
Prof. Dr. med. Ivo Buschmann
Chair of Angiology, Medizinische Hochschule Brandenburg | Clinic Director, University Clinic for Angiology
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Prof. Dr. med. Ivo Buschmann is Chair of Angiology at the Medizinische Hochschule Brandenburg Theodor Fontane and Clinic Director of the University Clinic for Angiology at the Brandenburg University Hospital.
He trained at the University of Hamburg, was a Max Planck Society Fellow at the Max Planck Institute for Heart and Lung Research, and held senior consultant posts at the Charite Universitatsmedizin Berlin before his appointment as Chair in 2016.
One of Europe's leading authorities on arteriogenesis, with over 150 peer-reviewed publications and US and EU patents, he reviews for PureLift LAB how the evidence on electrical stimulation is read and where its limits lie.
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A microamp is a millionth of an amp, every consumer microcurrent device quotes a few hundred of them, and all of those figures sit in the same band well below the level that moves a muscle.
This article explains what is actually happening, such as:
- what a microamp is, in terms you can picture
- why 335 and 680 are closer together than they look
- where the sensory and motor thresholds actually sit
- what the missing load and pulse width would tell you
- what each band of current can and cannot do
and many more!
The unit is simple; what brands leave off around it is where the difficulty lives.
Key Points:
A microamp is one millionth of an amp, and a milliamp is one thousandth, so 1 mA is 1,000 microamps.
Consumer microcurrent devices publish figures between about 200 and 680 microamps, all inside the same sub-sensory to barely-sensory band.
Muscle contraction needs current in the milliamp range, which is roughly an order of magnitude or more above any of those figures.
A current figure means little without the load it was measured at, because current through skin depends on resistance.
Pulse width matters as much as current, since tissue responds to charge, which is current multiplied by duration.
What the unit actually is
An amp measures the rate at which electrical charge flows. A milliamp is a thousandth of an amp, and a microamp is a millionth, so a thousand microamps make one milliamp.
For scale, a household circuit breaker trips somewhere around 13,000 to 30,000 milliamps, a TENS unit for pain typically works in the tens of milliamps, and a microcurrent facial device works in the hundreds of microamps, which is well under a single milliamp.
So when a brand quotes 500 microamps, it is quoting half of one milliamp. The number sounds substantial because the unit is small, which is part of why the unit gets used.
Why 335 and 680 are closer than they look
Across the devices that publish anything, Solawave gives about 200 microamps, ZIIP publishes 309, NuFACE files 335 with the FDA, 7E publishes 350 at 500 ohms, Therabody gives 500, and FOREO publishes 680.
Doubling from 335 to 680 sounds like a large difference, and in terms of what physically happens in tissue both figures sit comfortably inside the same band, below the level at which a motor nerve depolarises.
Ward and colleagues described the thresholds separating sub-sensory, sensory and motor stimulation, and the practical consequence is that moving from 335 to 680 microamps changes how much you feel rather than what category of effect you get.
7E Wellness states the point plainly in its own FAQ: true microcurrent is sub-sensory and cannot cause a physical or visual manipulation of the muscle. That is a manufacturer describing its own product accurately.
Where the motor threshold sits
To make a facial muscle contract, the current has to depolarise the motor nerve supplying it, and that takes current in the milliamp range rather than the microamp range.
Ya-Man's FDA filing for the Medi Lift PLUS publishes 3.22 mA at 500 ohms, which is about 3,220 microamps. PureLift publishes 7 mA at 500 ohms on Face and Pro, 7.7 mA on Pro Edition and 9 mA on Pro Plus and GLOW.
Kavanagh and colleagues measured an 18.6 percent increase in cheek muscle thickness across 108 women over twelve weeks using motor-level stimulation, which is the band those milliamp figures sit in rather than the microamp band.
None of that makes microcurrent useless. Avendano-Coy and colleagues reviewed microcurrent in wound healing and found measurable effects at sub-motor intensities, which is the honest case for the band: real effects at skin level, not muscle work.
The two numbers that are missing
The first is the load. Current through skin depends on the resistance it meets, so the same device measured into 500 ohms reads differently from the same device measured into 10,000 ohms, and both readings are true.
Of 33 devices we track, six publish an output figure on their own page and two state the load, which means most of the microamp figures in this market cannot be compared with each other at all.
The second is pulse width. Tissue responds to charge, which is current multiplied by how long each pulse lasts, so a device at 500 microamps with a long pulse delivers far more charge than one at 500 microamps with a short one.
7E's filing for the MyoLift QT gives pulse durations measured in hundreds of thousands of microseconds at frequencies below one hertz, while our devices run a 4 microsecond pulse at a much higher current. Those are entirely different delivery strategies that a single microamp figure hides.
What each band can do
Nanocurrent and low microcurrent, below roughly 100 microamps, is sub-sensory territory where you feel nothing and the claimed effects are cellular.
Microcurrent from roughly 100 to 1,000 microamps is where most consumer devices sit, producing skin-level effects and a mild tingle at the upper end.
Above about 1 milliamp, with the right pulse and frequency, you enter the band where the muscle responds and you can see the contraction in the mirror.
Which band your device occupies decides what is available to you, and the published figures for 33 devices will tell you where yours sits.
How to use the number when shopping
Treat a bare microamp figure as a rough indication of sensation rather than as a specification.
Ask for the load in the same breath, and treat a brand that cannot answer as having told you something anyway.
Ask for pulse width, which almost nobody publishes and which changes the picture completely.
And decide first which band you actually need, because a buyer who wants skin-level effects is well served by a good microcurrent device, while a buyer who wants contour change is not, whatever the microamp figure says.
This article sits inside our full map of the category, where we set out all 33 devices we track, what each one carries and what each brand publishes: Nine Technologies on One Dial, What the Rest of the Market Actually Carries.