Magnets are one of the few everyday industrial products that air carriers treat as potential dangerous goods — not because of what they are made of, but because of what their magnetic field can do to an aircraft in flight. A strong enough field, measured close to the package, can interfere with a plane's compass and navigation instruments. This is a real, regulated concern, not a shipping formality.
The rule in plain terms: UN 2807
Under IATA's Dangerous Goods Regulations, magnetized material is assigned UN number 2807. If the magnetic field strength measured at 4.6 metres (15 feet) from the surface of the package exceeds 0.00525 Gauss, the shipment is classified as Class 9 dangerous goods and subject to strict packaging, labeling and documentation rules before an airline will accept it. Packages that pass this test — because they are shielded or packed with enough separation and steel shielding to bring the field below that threshold — can usually ship as "excepted" from most of the formal dangerous goods process, but a written field-strength declaration is still standard practice.
What this looks like in practice
In practice, compliant magnet shipping means two things working together: a package design (steel shielding, keeper plates, spacing between magnets, orientation that cancels the external field) that physically brings the measured field below the regulatory limit, and the paperwork to prove it — a magnetic field strength test or declaration the airline's ground handling agent can check against. Get either one wrong and a shipment gets held at the origin airport, not at customs on arrival, which is the more disruptive and harder delay to explain to an end customer.
What we do on every air shipment
We pack magnetized material to IATA and IMDG requirements by default, not as a special request: shielded cartons, measured external field strength before the shipment leaves our facility, and the declaration documentation included with the airway bill. If a project needs a specific packaging configuration for an unusually strong or large magnet, tell us the grade and dimensions during the quote stage and we will confirm the shielding approach before production, not after the shipment is already built.