EMFBase

Microwave oven

The only consumer appliance with its own federal leakage standard: 5 mW/cm² at 5 cm from the surface over the product's lifetime, which is 50,000,000 µW/m² — high compared with any communications source.

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Last verified 12 August 2026.

Also searched as: microwave leakage

Category
radiofrequency
Emission bands
2.45 GHz ISM
Environments
home, workplace
Transmit power
1,000 W EIRPRegulatory value — legally enforceable — Cavity magnetron output is roughly 700–1200 W, contained by the cavity and door screen; the regulated quantity is leakage, not output.sources: fda-microwave, fcc-part18
Duty cycle
Only while cooking. Older or damaged door seals and hinges are the usual cause of elevated leakage.

Field strength by distance

5 cm
5 × 10^7 µW/m²Regulatory value — legally enforceable — FDA limit for leakage over the lifetime of the oven: 5 mW/cm² at 5 cm. New ovens are required to be below 1 mW/cm² at 5 cm. Well-maintained ovens typically measure far below both.sources: fda-1030-10, fda-microwave
1 m
125,000 µW/m²Computed estimate — Inverse-square scaling of the 5 cm FDA leakage limit to 1 m (factor of 400). — Upper bound implied by the leakage limit, not a typical measurement.sources: fda-1030-10, itu-fs-relations

Mitigations, most effective first

Stand back a metre or more while the oven runs rather than watching through the door.
Leakage falls with the square of distance, and the limit is defined at only 5 cm.
Check the door seal, hinges and latch; replace ovens with visible door damage.
Door integrity is the dominant variable in leakage measurements.
Measure at 5 cm around the door perimeter with an RF meter that reads up to at least 20 mW/m².
Most consumer RF meters saturate near a running microwave; check the meter's range before concluding.

Measure with

  • Broadband RF power-density meter
  • Microwave oven leakage tester

Related records

  • Power density

    Radiofrequency energy flow per unit area — µW/m² on consumer RF meters, mW/cm² in FCC rules, W/m² in ICNIRP guidelines. 1 mW/cm² = 10 W/m² = 10,000,000 µW/m².

    Quantities & units

Sources

  1. fda-1030-10 21 CFR 1030.10 — Microwave ovens (radiation emission performance standard) U.S. Government Publishing Office (eCFR). regulation, link checked 2026-08-12.
  2. fda-microwave Microwave Ovens U.S. Food and Drug Administration. government, link checked 2026-08-12.
  3. fcc-part18 47 CFR Part 18 — Industrial, Scientific, and Medical Equipment (includes microwave ovens) U.S. Government Publishing Office (eCFR). regulation, link checked 2026-08-12.

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