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Wavy lines, or a dish beneath them, indicating microwave use.
Also known as: Microwave symbol, Wavy lines symbol, Microwaveable symbol
Wavy lines mark a container as suitable for microwave use. There is no standard for it: the drawing varies between manufacturers, and it is the manufacturer's assurance rather than a certification.
Is not a standardised symbol. No body defines it, its drawing varies between manufacturers, and its presence is the manufacturer's own assurance rather than a certification — so the absence of the mark does not reliably mean the object is unsuitable, and its presence is not a guarantee.
Stated first rather than as a footnote, because it is the most useful thing to know about the mark. Check the manufacturer's own instructions where it matters.
Contexts: Packaging
Indicates that a container is intended to be used in a microwave oven, usually drawn as two or three horizontal wavy lines, sometimes above a dish.
Contexts: Packaging
Is often crossed through or shown inside a barred circle to mean the opposite — that the container must not be microwaved, most commonly because it contains metal.
Contexts: Packaging
Concerns the container rather than the food: a microwave-safe dish will not be damaged by the process, which is a different question from whether the food inside heats safely or evenly.
Contexts: Packaging
Has no standardised form. Manufacturers use wavy lines, a drawing of a microwave oven with wavy lines inside it, or a dish with wavy lines above it, and all three mean the same thing. That is why a reader hunting for a single canonical microwave symbol cannot find one.
Contexts: Packaging
Is often qualified in small print that matters more than the symbol. 'Microwave safe' on a container may mean reheating only rather than cooking, and a lid marked separately from its base is common — the two parts of the same box frequently do not carry the same permission.
Contexts: Packaging
Related forms that are not treated as separate canonical symbols — see our variant rules.
Wavy lines alone
Two or three horizontal wavy lines, the most abbreviated form and the one most often moulded into a plastic base.
Oven outline with waves
A box representing the oven cavity with wavy lines inside it, used where the bare waves were thought ambiguous.
Dish with waves above
A plate or bowl with wavy lines rising from it, the form commonest on packaged ready meals.
Two or three horizontal wavy lines stacked one above another, sometimes drawn above a shallow dish shape.
Both appear on the base of the same container. This one is about heating and is not standardised; the glass and fork is about the material and is defined in law.