The Pan Makes the Heat, Not the Cooktop

You put a pot of water on the cooktop and turn it on. The water starts to heat. The glass surface under the pot stays cool enough that you could touch it. No flame, no glowing red element, no heat radiating into the room. Just a cold surface and a hot pot.

That is not magic. It is a transformer. The coil in the cooktop is the primary winding, the pan is the secondary winding, and the current in the coil induces a current in the pan. The pan gets hot because it has electrical resistance. The cooktop stays cool because it does not.

The pan is the heating element

An induction cooktop contains a coil of copper wire just below the glass surface. When you turn the cooktop on, the control electronics send an alternating current through the coil at a frequency between 20 and 50 kilohertz. That current creates an oscillating magnetic field. The field passes through the glass and into the base of the pan.

If the pan base is ferromagnetic, the magnetic field induces circulating currents called eddy currents in the metal. Those currents encounter electrical resistance, and resistance produces heat. The pan heats itself. The IEEE author page for Mehmet Emin Tulu describes the principle plainly: the coil and the load act as a transformer if the load has an electrically conducting base, and if the base is ferromagnetic, the power is transferred with high efficiency.

The cooktop does not heat the glass. The glass is transparent to the magnetic field. The heat you feel on the surface after cooking is conducted back from the pan, not generated by the cooktop.

Which pans work and which do not

A ferromagnetic base is required. That means the base must contain iron, steel, or another material that a magnet will stick to. The patent literature is direct: tri-ply, high-quality stainless steel, and cast iron cookware will work. Copper, glass, and aluminum will not work unless they have a sandwiched magnetic base. The Philips support page recommends cookware with a flat bottom and a base diameter between 12 and 20 centimetres. The Samsung cooktop guide states that any and all cookware used on an induction cooktop must have a magnetic base, and the simplest test is a magnet.

Most people already own at least one induction-compatible pan. The CHOICE fact-check article notes that cast iron, steel, and some enamel steel and stainless steel pans work if the base is a magnetic grade of stainless steel. A magnet that sticks firmly to the base is a reliable indicator. If the magnet slides off, the pan will not work.

Why the efficiency is so high

Induction cooking transfers about 84 to 90 percent of the energy it draws into the pan, according to the Carbo Europe efficiency comparison. Gas cooking transfers about 40 percent. The rest escapes as ambient heat, heating the kitchen instead of the food. Standard electric coil and glass cooktops reach about 74 percent.

The gap in practice is visible in boiling times. CHOICE measured one litre of water on an induction cooktop and it reached a boil in two minutes and 19 seconds. A gas cooktop took four minutes or longer. That is not a small difference. It changes how you plan a meal.

What it costs to install

Purchase prices for induction cooktops range from about $900 to $4,100 for residential models, according to the 2026 Stove Shield comparison. Commercial-grade units start around $200 for a small countertop single-zone model and go up from there, according to the 2026 market report.

Installation is where the cost can surprise you. The CHOICE article explains that induction cooktops often need a dedicated circuit. A new circuit with a safety switch can cost between $600 and $1,200. If a full switchboard or mains upgrade is required, the cost can run from $3,000 to $9,000. Some newer low-current induction models, designed to run on existing 20-amp wiring, can avoid the circuit upgrade.

What the magnetic field does when you step away

The same magnetic field that heats the pan also radiates outward. A 2025 study in Bioelectromagnetics measured the stray fields from a range of induction hobs and found that at distances close to the cooktop, the fields exceed the reference levels set by international safety guidelines. The study also found wide variation between models, with differences of more than a factor of 20 depending on power, coil size, and proximity. The finding matters because it suggests that low-exposure designs are possible without sacrificing cooking performance.

The German Federal Office for Radiation Protection states that at common distances from the hob, appliances usually comply with the reference value of 27 microtesla for magnetic flux density. The 2025 study suggests that the testing standard used for compliance may underestimate exposure for someone standing right next to the cooktop. If you are pregnant or have an implanted medical device, keep a reasonable distance from the cooktop while it is on. The field drops rapidly with distance.

What to look for next time

The next time you see an induction cooktop, look at the surface. If there is no pan on a zone, the zone will not heat. If the pan is not magnetic, the zone will not heat. The cooktop is not a hot plate. It is a coil, a magnetic field, and a pan that completes the circuit. The pan is the heating element, and the cooktop is the switch.

Check the bottom of your pans with a magnet before you shop. Check the electrical panel before you buy. And check the model’s exposure measurements if you stand close to the cooktop while it runs.