Stay warm,
keep the bill tiny.
An electric blanket is
just right.
The short version…
- About ¥0.8 an hour on medium — about ¥6 for a whole night
- It warms your body, not the room. Great in bed, on the sofa, at your desk
- Switch to low or use the timer when you sleep, to avoid low-temperature burns
Electricity cost calculator
For electric blankets, calculate with energy used per hour (Wh), not the rated wattage. The figures below are maker-published values for a 55W-rated blanket (Yamazen YFTKB-55).
Same hours with other heaters? (per month)
At 31 yen/kWh (guideline unit price, revised July 2022). Compared with: ceramic heater 600W low / 1,200W high (typical specs), kotatsu about 170Wh per hour on high (Yamazen 510W model). Real costs vary with model, room temperature and your plan.
Power outage: how big a portable power station?
With these settings you need about - or more.
Formula: Wh per hour × hours ÷ 0.8. The 0.8 factor is the rule of thumb power-station makers (Anker, EcoFlow) give for usable capacity (confirmed in an article dated September 20, 2026). It isn't a guarantee for your unit — leave some margin.
Warm the bed on high before you get in, then switch to low. Cheapest and most comfortable.
Our picks by type
- Use it over or under you
- Room sensor, auto-off, washable
- About 0.6 yen/h (medium, ~18Wh)
- For feet at your desk or on the sofa
- Buttons to wear it as a shawl help you move
- About 0.7 yen/h (medium, ~23Wh)
* Products and prices are loaded from Rakuten Ichiba when the page opens.
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Who it suits — and who it doesn't
○ Good for you if…
- Cold feet keep you awake in bed
- Sleeping with the air conditioner on dries your throat
- You sit still for hours working from home or on the sofa
- You want to keep winter electricity bills down
× Not for you if…
- You want to heat the whole room or the whole family
- You move around the house a lot
- You want the room warm as soon as you get home
- You run hot and can't sleep if the bed is too warm
Under you, over you, or both?
A thin heating wire runs through the fabric and gets gently warm. No airflow, no noise. There are three main types:
Choose by where you'll use it
* If you keep it on while you sleep, use low or a timer. Check the manual before combining it with a kotatsu or hot-water bottle.
Why is a "55W" blanket so cheap?
The "55W" on the box is the maximum (rated) power. Once warm, the blanket switches the heat on and off by itself, so the energy it actually uses in an hour is much lower. Spec sheets list this separately as "energy per hour" (消費電力量).
| Product | Rated | High | Med | Low |
|---|---|---|---|---|
| Yamazen YFTKB-55 ~210×150cm / over | 55W | ~37Wh | ~25Wh | ~10Wh |
| Koden CWB551 series ~188×130cm / both | 55W | ~31Wh | ~18Wh | ~3Wh |
| Koden CWB801G-HT ~188×130cm / both | 80W | ~50Wh | ~27Wh | ~6Wh |
Energy per hour is the average over 5 hours inside a cotton futon at a room temperature of 15°C (makers' test conditions, based on the Japan Electrical Manufacturers' Association method and similar). Checked on each maker's product page on October 16, 2026. Real rooms vary.
5 tips for choosing
-
Choose type and size by where you'll use it
For the bed, a 2-way blanket (かけしき, about 188×130cm) can go over or under you. For a desk or sofa, a lap-size blanket is enough.Where Type Bed / futon 2-way (かけしき) or under-blanket (敷き) Sofa / desk Lap blanket (ひざ掛け) Keep your current duvet Cover type that attaches to the duvet -
A room-temperature sensor means less fiddling
It adjusts to the room temperature, so you're less likely to wake up too cold or too hot. -
Auto-off and timers
Auto-off after 8 or 12 hours, or a timer set to your sleep and wake times, prevents leaving it on. -
Is it machine-washable?
It touches your skin, so washing matters. Many can be machine-washed once you detach the controller. Check each product's washing instructions (net, spin time, etc.). -
Extras: dust-mite mode, warmer-feet wiring
A high-heat "dust mite" (ダニ退治) mode, or wiring that warms the feet more (頭寒足熱). Not essential, but handy for the bedroom.
Common mistakes
Instead: use high only to warm the bed. Switch to low or a timer when you sleep. Makers list a surface temperature of about 51–52°C on high
Instead: there's a risk of low-temperature burns, so don't keep heat on one spot for long. Take extra care with small children, older people, and anyone who can't easily adjust the heat
Instead: spread it out flat. Damaged heating wire can break or overheat
Instead: always remove the controller and cord before washing. Reconnect only when fully dry
Good to know if you live in Japan
-
Buy a heater made for Japan (100V)
Japan's household power is 100V. A heater built for 220–240V countries won't work properly here, and adapters don't fix that. Choose a model sold in Japan. -
Look for the PSE mark
Electric heaters, electric blankets and kotatsu are covered by Japan's Electrical Appliances and Materials Safety Act. Products sold in Japan must carry the PSE mark — be careful with very cheap imports from marketplaces. -
Manuals are usually in Japanese
Many makers post their manuals as PDFs on their websites. A camera-translation app works well for the safety page and the control panel. -
Shopping in English
Amazon.co.jp can be switched to English in the language settings. Product titles are often still in Japanese — search with the Japanese name (shown on this page) to find more options. -
Your price per kWh may differ
We calculate with 31 yen/kWh, the guideline price used in Japanese catalogs. Your actual price depends on your power company and plan — check your monthly bill (検針票 / your company's app).
FAQ
Can I leave it on all night?
Can I wash it?
How much cheaper is it than an air conditioner?
Still not sure?
6 questions to find the heater that's just right for you.