An induction pan not detected by the cooktop may have a magnetic base smaller than its advertised rim. The rim diameter printed on the box can be much larger than the flat magnetic area underneath. Before buying a new pan, check where a magnet sticks, measure that area, and compare it with your cooktop’s minimum pan size.
Use this guide’s measurement table to compare the flat contact base and magnetic area with your hob model’s detection requirements; it also helps before purchase. If an existing pan is not detected and you need pan-and-zone comparisons and records for a service enquiry, see Check an existing pan and record the results for service.
Test more than one point on the underside
Hold a magnet against the center of the cool pan’s base, then check toward its edges. LG’s cookware guide warns that a pan with an IH mark may still perform poorly if only part of its base is magnetic. GE Appliances suggests the magnet test as a first compatibility check.
Passing the magnet test is necessary for many induction setups, but it is not a universal pass. A small, warped or off-center base can still fail detection or deliver less power. Test only when the pan and cooktop are cool.
Measure the flat magnetic base, not the rim
Record the diameter of the flat part that contacts the glass, then the span across which a magnet actually sticks. Check your exact cooktop manual for its minimum detectable pan size on the chosen zone. GE’s size guide makes this distinction and explains why a wide frying pan can have a much smaller magnetic base.
| Record this | How to check it | Compare with |
|---|---|---|
| Advertised or rim diameter | Read the packaging; treat as a reference | Not the detection specification |
| Flat base diameter | Measure the area touching the glass | Zone size recommendation |
| Magnetic span | Move a magnet from center outward | Model’s minimum detectable size |
| Pan position | Center the base on the marked zone | Manual’s placement illustration |
Illustrative example only: a pan sold as 24 cm wide could have a 17 cm flat base and a smaller magnetic area. Those numbers do not describe a tested model or promise compatibility. Use your own measurements.
The magnet sticks, but the hob still shows no pan
- Center the pan on the cooking-zone graphic.
- Check whether its base is flat rather than bowed or raised on feet.
- Try another pan already known to work on that zone. If it works, investigate the first pan’s base and size.
- If several known-compatible pans fail on the same zone or an error persists, stop and consult the model manual or service provider.
Do not let a large pan overlap touch controls or metal trim. An oversized rim does not extend the induction coil’s heated area, as GE notes. This is a cookware-fit decision, not necessarily a cooktop-failure diagnosis.
Keep a short compatibility record: flat base diameter ___ cm / magnetic span ___ cm / zone tested ___ / cooktop model ___. If another known-compatible pan works on that zone, compare the first pan’s base and shape before treating the cooktop as faulty. This record also gives the manufacturer a specific question to answer.
Sources checked 28 September 2026. This article compares LG and GE manufacturer guidance. We did not test a pan or cooktop.