Not microwave-safe (crossed-out waves)
The maker says the item must not go in a microwave oven. Mepal gives the usual reason: the material ‘should not be heated in this way’.
Market convention
This symbol is a market convention: no law or public standard defines the drawing, so each maker draws its own and the meaning is whatever that maker says it is. This page follows 2 makers’ and retailers’ own keys.
- What it looks like
- The microwave symbol — wavy lines, or a small microwave — with a diagonal line or an X through it.
- Other names
- do not microwave symbol; no microwave symbol; crossed out microwave; not microwavable
What it does not promise
The crossed-out waves only warn against microwaving. An item without this mark is not thereby microwave-safe: for many makers the absence of the plain microwave symbol is the warning, with no crossed-out version printed at all.
Where makers differ
Mepal strikes a single diagonal through its three-wave square and says you will see it often, because ‘Quite a few of our products are not suitable for use in the microwave’. Million Pack describes both a crossed-out microwave and crossed-out waves. Many makers print nothing at all instead; Sistema, for example, says an item without its microwave symbol cannot be microwaved.
Often confused with
The maker says the item may be used in a microwave oven. It is about the container, not the food: Mepal explains that when the symbol is crossed out, it is often because the material ‘should not be heated in this way’.
Sources
No law defines this symbol, so the meaning is taken from makers’ and retailers’ own pages. Those marked as showing the icon draw or describe it; the others add conditions. Each was fetched and read on the date shown:
- Mepal : What do the symbols and specifications on a product mean? — Shows the three-wave microwave icon with a diagonal line through it: ‘If there is a cross through it, the product cannot be used in the microwave. This is often because the material the product is made from should not be heated in this way.’ Checked 2026-09-24.
- Million Pack (food-packaging manufacturer, Ningbo) : What the Microwave Safe Symbol Looks Like and Means? (10 November 2025) — Shows ‘Crossed-Out Microwave or Waves’: ‘a microwave icon or a set of wavy lines with a bold diagonal slash running through it’, used to indicate that the item ‘should not be used in a microwave under any circumstances’. Checked 2026-09-24.
- Sistema: FAQ's — Uses absence rather than a crossed-out icon: ‘Our products without engraved microwave symbol cannot be used in microwaves.’ Checked 2026-09-24.
Written in our own words; quotations are the sources’ wording.