Three measurements describe what a PEMF device puts out: how strong the field is, how fast it changes, and how much heat the coil makes. Here's what each one means, using a device we measured.

Whoever draws a PEMF mat's field map decides how to fill the space between scan lines and where the color scale tops out. Here's how each choice changes the same data.

Buyer guides now say a sealed mat can't be checked. It can: the field sits in the air above the pad. See every test point and its Gauss value, at the height a body actually lies.

PEMF certification means two different things. One certifies a person who completed training, and the other certifies what a device and its accessory were measured to put out. Only the second describes the hardware you are buying.

The FEI is proposing to cut the permitted PEMF field at its events from 1,000 Gauss to 100, and to require battery power. A battery limits the current a device draws continuously rather than the energy it stores between pulses, so it does not set the peak field.

Some PEMF companies leave the peak Gauss value off the product page because one value on its own misleads. The reasoning is sound, but a blank spec sheet leaves a buyer with nothing to compare. Here are four values to publish beside a peak.

Once we have tested your device and accessory, the interactive 3D view of its measured field can sit on your own product page. Paste one line of code from your customer portal, choose who each product is shown on and which views visitors get, and preview it before you save.

PEMF spec sheets have started publishing a slew rate, usually in tesla per second. Here are the four facts that have to sit beside it before you can compare two devices.

One line of readings can't tell you if a PEMF accessory is stronger on one side. Here's how we scan four lines out from the center, and the five values that scan produces.

Three PEMF certifications went on the public Gauss Labs registry in August. Here is what went up, why one device and two accessories produced three separate listings, and how to check a certification badge yourself in about a minute.