Value Village ／ Food & living
This answer is a draft. It stays unpublished until legal review and source verification are complete.
The rice cooker is the centre of the Japanese kitchen, and "Japanese rice cookers" are popular abroad too. "How many hours can I leave rice on keep-warm?" and "Can I cook other things in it?" are questions the Association for Electric Home Appliances and the makers answer again and again. Here are the numbers behind their answers.
| Item | Content | Source |
|---|---|---|
| Keep-warm temperature | About 70–75°C (a range that suppresses bacterial growth) | Manufacturer materials |
| Keep-warm guide | Within 12 hours (up to 24 hours on some models). Taste declines after 5–6 hours: yellowing and smell | Major makers' instruction manuals |
| Keep-warm electricity | About ¥0.4–0.6 per hour (15–20 W), about ¥5–7 for 12 hours. Freezing and reheating in the microwave usually costs less overall | Association for Electric Home Appliances; Agency for Natural Resources and Energy |
| Cooking electricity | About ¥4–6 per batch (5.5 gō — 合, roughly 1 litre of uncooked rice — about 150 Wh) | Same |
| Lifespan of a rice cooker | 6–10 years (the inner pot's non-stick coating degrades in 3–5 years) | Association for Electric Home Appliances |
[Verify] Check keep-warm times and electricity costs in your model's instruction manual and on the maker's website, and accident cases with NITE.
Around 70°C suppresses bacterial growth, but some models switch keep-warm off, or let the temperature drop, after 24 hours, and the taste falls within hours. Within 12 hours; beyond that, freeze.
¥0.4–0.6 an hour is small, but 12 hours equals one cooking cycle. Portion and freeze as soon as it is cooked, then microwave — better on both taste and electricity.
Only compatible models and their listed menus. Thick, sticky dishes (curry, stew, cake) and large amounts of oil or baking soda cause blocked steam vents, breakdowns and damage to the inner pot in non-compatible models.
It damages the coating, and the rice starts to stick. Rinse in a bowl, or check for the "washing in the inner pot OK" (内釜洗米OK) label. Avoid metal measuring cups and paddles too.
If the inner pot's coating peels, replace just the inner pot (most makers sell it as a spare part). Failing to cook, keep-warm not working, or a strange smell means the body has reached the end of its life. Spare parts are held for 6 years after production ends as the industry guide (see our article on warranties and repairs).
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https://www.aeha.or.jp/
https://www.enecho.meti.go.jp/category/saving_and_new/saving/general/howto/
https://www.nite.go.jp/jiko/chuikanki/
⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.
What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.
This is general information. Results vary from person to person and depend on your own conditions and surroundings.
Please decide for yourself, using your own judgement, whether any of this suits your situation. We cannot accept responsibility for any damage, loss or injury arising from following this article.
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