The first properly cold morning in a Japanese apartment is a small shock. You wake up, your breath is visible indoors, and the only heating device in the whole place is the air conditioner bolted above the window. I grew up in Malaysia, where heating a home isn’t a thing anyone thinks about, so I had to learn from scratch what actually keeps a small apartment warm here, and what it costs.
This guide covers heating a Japanese apartment in winter with the 5 options you’ll actually find on shop shelves: the aircon, a kotatsu, an electric blanket, an oil heater, and a ceramic fan heater. I ran every one of them through the same electricity price so you can compare them on one scale. I’m a mechanical engineer, so yes, there’s a bit of physics. It’s the useful kind, I promise.
Some links in this article are Amazon affiliate links. If you buy through them I may earn a small commission at no extra cost to you. Prices are what Amazon Japan showed in October 2026 and they move around a lot. Amazonのアソシエイトとして、nihonshouhin.comは適格販売により収入を得ています。
Why your apartment has no central heating
Most Japanese rental apartments heat one room at a time. There’s no boiler and no radiators. The wall-mounted aircon does both cooling and heating, and that’s the system. If you’ve wondered why the units look the way they do, I wrote about that in why Japanese air conditioners look different from the rest of the world.
So the choice you’re really making is between 2 approaches. You can heat the air in the room, or you can heat the person sitting in it. Aircons, oil heaters and fan heaters heat the room. Kotatsu tables and electric blankets heat you. That split explains almost every running cost difference further down.
The one number to keep in your head: ¥31 per kWh
Every Japanese appliance box and catalogue quotes running costs using the same electricity price: 31 yen per kWh. That’s the reference price set by the Japan Fair Trade Council for Home Electric Appliances (全国家庭電気製品公正取引協議会), raised from 27 yen in July 2022. Your real rate depends on your power company and plan, but 31 yen is the number manufacturers use, so I’ll use it too.
The maths is simple. Take the wattage, divide by 1,000, multiply by 31. A 1,200W heater on full costs 1.2 × 31 = about 37 yen per hour. Run it 8 hours a day for a month and you’re looking at almost 9,000 yen, from one device.
Keep that 37 yen in mind. It’s the benchmark for “expensive” in this article.
Your aircon is a heat pump, which is why it wins for the room
Here’s the bit of physics. A heater with a glowing element or hot oil turns 1 kWh of electricity into 1 kWh of heat. That’s it. It can’t do better, because all it’s doing is resisting current.
An aircon in heating mode moves heat from outside to inside. The outdoor unit pulls heat out of the cold outside air (yes, there’s still heat in 5°C air), compresses the refrigerant to push its temperature up, and dumps that heat into your room. The electricity only runs the compressor and fans.
Take a real example. The Daikin S225ATES-W is a standard 2025 model rated for about 6 tatami (畳) of heating. According to its spec sheet on kakaku.com, it puts out 2.2 kW of heat while drawing 470W of electricity. That’s a ratio of 4.68, which engineers call the COP (coefficient of performance). You get 4.68 units of heat for every unit of electricity you pay for.
Translate that into yen. At 31 yen per kWh, heat from an oil heater or fan heater costs 31 yen per kWh of heat. Heat from that Daikin costs about 6.6 yen per kWh of heat. Same warmth, under a quarter of the price.
Running the S225ATES-W at its rated 470W works out to about 14.6 yen per hour. Over 8 hours a day for 30 days, that’s roughly 3,500 yen. That’s an illustrative figure at a constant rated load. Your real bill depends on insulation, outdoor temperature and how hard the unit has to work.
The catch with aircon heating
That 4.68 figure is measured under the Japanese test standard (JIS), with 7°C outside. When it’s colder, the outdoor unit has to work harder to find heat, so the COP drops and the electricity draw goes up. On a frosty morning the unit will also pause now and then to defrost its outdoor coil, and you’ll feel the warm air stop for a few minutes. That’s normal.
The bigger issues are comfort ones. Warm air rises, so your head is toasty while your feet are on cold flooring. And heated air gets dry fast. If your throat feels like sandpaper by February, a humidifier helps a lot. I went through humidifying air purifiers in which air purifier should you get in Japan.
One habit that helps: start the heating before you get home or before you wake up, so the unit isn’t fighting a fully cold room at full power while you stand there shivering. You can do that from your phone with most modern Japanese aircons, or with a cheap smart remote for older ones. The setup is in how to control a Japanese aircon from your phone.
If your aircon is old, check the filter before winter starts. A clogged filter cuts airflow, and the unit burns more power to push the same heat through.
Kotatsu: heat the person, ignore the room
A kotatsu (こたつ) is a low table with a heater fixed underneath and a thick futon blanket sandwiched under the tabletop. You sit on the floor, put your legs under the blanket, and the heater warms that small enclosed space. The rest of the room can be 12°C and you won’t care.
The numbers are almost silly. The Yamazen SEU-752 kotatsu table (75cm square, about ¥7,380) has a 300W heater. But the heater cycles on and off once the space under the blanket is warm, and Yamazen lists the real hourly consumption as about 160Wh on high and 80Wh on low. That’s about 5 yen per hour on high and 2.5 yen on low.
8 hours a day for a month on high comes to around 1,200 yen. On low, about 600 yen.
The table on its own is just a table, though. You need a kotatsu futon to trap the heat. If you’re starting from zero, Yamazen sells the same 75cm table bundled with a futon for about ¥14,999, which saves you measuring and guessing sizes.
There are 2 real downsides. First, you have to live at floor level. If your apartment has a sofa and a dining table, a kotatsu doesn’t fit your life. Second, the kotatsu is famous in Japan for making people unable to leave it. That’s a joke and also completely true.
Electric blankets: the cheapest heat in the house
Running a heater all night in an empty-feeling bedroom is where a lot of winter electricity goes. An electric blanket (電気毛布) skips the whole room and warms the bed.
The Koizumi KDK-60242 (188 × 120cm, about ¥5,930) draws 60W at its maximum setting. That’s under 2 yen per hour, flat out. A full 8-hour night on max costs about 15 yen, and in practice you’ll run it lower than that once the bed is warm. It’s machine washable and can go under you or over you (掛敷兼用, “use on top or underneath”).
My suggestion is to warm the bed for 20 to 30 minutes before you get in, then turn it down to low or off. Follow the manual on the safety side: don’t use it folded or bunched up while it’s on.
If I could only buy one heating gadget for a first winter in Japan, this would be it. It costs less than a dinner out and it covers the 7 or 8 hours you spend in bed every night.
Oil heaters: silent, gentle, and expensive to run
Oil heaters look like old-fashioned radiators on wheels. Inside the fins is sealed oil that an electric element heats up, and the hot fins warm the room by radiation and slow convection. There’s no fan and no flame. They’re nearly silent and they don’t blow dust around. They don’t stop the air getting drier, though. Any heater lowers the room’s relative humidity, because it warms the air without adding water: Daikin explains this for aircon heating, and the physics is the same for an oil heater. What an oil heater avoids is a stream of warm air blowing across your skin, which is a big part of why fan heaters and aircons feel so drying.
That’s why people love them in bedrooms and in homes with small kids. De’Longhi is the brand everyone in Japan knows for these. The De’Longhi RHJ10F0812-SG (about ¥22,589) has 3 settings: 500W, 700W and 1,200W.
Now look at the running costs. 500W is 15.5 yen per hour. 700W is 21.7 yen. 1,200W is 37.2 yen, the same “expensive” benchmark from earlier. Run it on the middle setting for 8 hours a day and you’ll pay about 5,200 yen a month. On high, about 8,900 yen.
Remember the physics: an oil heater turns 1 kWh of electricity into 1 kWh of heat, exactly like a cheap fan heater. It’s a pleasant way to deliver heat, and an expensive one. The Daikin aircon above delivers 2.2 kW of heat for less electricity than the oil heater’s lowest setting.
Oil heaters are also slow. They can take a good 20 to 30 minutes before you feel the room change, so they suit “on all evening” use far better than “I need to be warm right now”. I’d only get one if I disliked the aircon blowing directly at me and drying my skin.
Ceramic fan heaters: for the rooms you’re in for 10 minutes
A ceramic fan heater (セラミックファンヒーター) pushes air over a hot ceramic element. It’s loud-ish, it’s fast, and it has the same 1-to-1 efficiency as the oil heater. Where it earns its spot is the small rooms with no aircon at all: the changing area outside the bath (脱衣所) and the toilet.
Those cold spaces matter more than you’d think. Japan has a word for the danger, ヒートショック (heat shock): going from a warm room into a freezing bathroom and then into a hot bath puts real strain on your blood pressure, and it’s a known risk for older people here. A small heater in the changing room takes the edge off.
The Panasonic DS-FAS1200-W (about ¥8,855) runs at 1,150W on high and 640W on low. Panasonic rates it IPX1 drip-proof (防滴), which it describes as the most basic level of water protection: it’s tested against water dripping straight down, and Panasonic designs it for washrooms, toilets and kitchens. That makes it reasonable for a changing room, but keep it away from the shower and anywhere it could be splashed. That’s 35.7 yen per hour on high, 19.8 yen on low.
For a toilet or a tiny space, the Iris Ohyama JCH-M082T (about ¥5,980) is smaller, at 800W or 400W, and it has a motion sensor (人感センサー) that switches it off when you leave. That sensor is the whole point. A fan heater left running in an empty room is the most expensive mistake on this list.
Use these in short bursts. 10 minutes at 35 yen per hour is 6 yen. 8 hours is a different story.
What about kerosene heaters?
You’ll see kerosene heaters (石油ストーブ and 石油ファンヒーター) everywhere in Japan, especially in older houses and in the north. They put out a lot of heat and plenty of households swear by them.
They’re most common in rural areas, where storms can cut the power and people have space to store fuel in a garage or shed. If you rent, check your lease first, because some apartments ban kerosene heaters outright. They also burn fuel inside your room, so the manuals tell you to ventilate regularly, and you’ll be carrying 18-litre tanks of kerosene home. Living in a city or suburb, I wouldn’t get one.
A quick word on the Dyson in the rankings
On the kakaku.com air purifier ranking for October 4 to 10, the Dyson Purifier Hot + Cool HP10 sits at #8. Its heating side is still an electric element blowing hot air, so per kWh of heat it costs the same as the ceramic heaters above. You’re paying the Dyson price for the purifier and the design, which is a fair thing to want. For heat alone, a ¥6,000 fan heater gives you the same warmth per yen.
Running costs side by side
All figures use 31 yen per kWh. “Monthly” assumes 8 hours a day for 30 days, which you won’t do with a bathroom heater, but it keeps the comparison fair. These are illustrative constant-load scenarios for comparing devices, not predictions of your bill.
| Device | Power (W) | Cost per hour (yen) | Monthly at 8h/day (yen) | Heats |
|---|---|---|---|---|
| Daikin S225ATES-W aircon (6 tatami) | 470 (rated) | 14.6 | ~3,500 | Room |
| De’Longhi RHJ10F0812-SG oil heater | 500 / 700 / 1,200 | 15.5 / 21.7 / 37.2 | ~3,700 / ~5,200 / ~8,900 | Room |
| Panasonic DS-FAS1200-W fan heater | 640 / 1,150 | 19.8 / 35.7 | ~4,800 / ~8,600 | Small room |
| Iris Ohyama JCH-M082T fan heater | 400 / 800 | 12.4 / 24.8 | ~3,000 / ~6,000 | Small room |
| Yamazen SEU-752 kotatsu | ~80 / ~160 (actual hourly) | 2.5 / 5.0 | ~600 / ~1,200 | You |
| Koizumi KDK-60242 electric blanket | 60 (max) | 1.9 or less | ~450 or less | You |
The aircon row has an asterisk in real life: on very cold days it’ll draw more than its rated 470W. Even so, it stays the cheapest way to warm the whole room by a wide margin.
What I’d do in a 1K or 1LDK
Here’s a sensible setup if you’re facing your first Japanese winter in a small apartment.
- Use the aircon you already have as the main heater for the living space. Set it to around 20°C, start it remotely before you get home, and clean the filter.
- Buy an electric blanket for the bed and turn the aircon off at night. This one change probably saves more than anything else on the list.
- Add a kotatsu only if you actually sit on the floor. If you do, it’ll become the centre of your winter.
- Put a small ceramic heater with a motion sensor in the changing room, and only there.
- Skip the oil heater unless the aircon’s airflow bothers you or dries your skin.
That whole kit (blanket, kotatsu set, small fan heater) costs roughly ¥27,000 at current Amazon prices, a bit more than one De’Longhi oil heater. And it’ll cost a fraction as much to run.
One last thing. Windows are usually the weakest spot. In many older Japanese apartments they’re single-pane glass in aluminium frames, and you can feel the cold coming off them. Thick curtains that reach the floor help, and so does closing them as soon as the sun goes down. It’s the cheapest heating upgrade there is.
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