Ceramic heater or
air conditioner:
which costs less?
A ceramic heater makes sense for a few minutes in a changing room or toilet, or to warm your feet. Ten minutes costs about 6.2 yen.
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Why the costs are so different
A ceramic heater heats a ceramic element with electricity and blows warm air with a fan. 1 kWh of electricity gives about 1 kWh of heat. An air conditioner moves heat in from the outdoor air, so it gets about 2–5 times as much heat from the same electricity (see oil heater vs air conditioner for details).
The other difference is heating power. A ceramic heater tops out at 1.2 kW; Daikin's 6-tatami air conditioner (S225ATES) can put out up to 3.9 kW. Try to heat a whole room with one ceramic heater and it runs on high for hours — and the bill climbs.
| Ceramic heater | AC (6 tatami) | |
|---|---|---|
| Heat output | 0.6–1.2 kW | 0.7–3.9 kW |
| Power used | 600–1,200 W | 130–1,280 W |
| Warm-up | Instant | A few minutes |
| Best at | Feet and small spaces, briefly | Whole room, for hours |
Keeping a room warm: comparison tool
For the air conditioner, we take the heat needed to keep the room at that temperature (derived from an oil heater estimate) and divide it by a multiplier for the outdoor cold. For the ceramic heater, we assume a model without a thermostat running at the setting you choose.
Monthly electricity cost
Ceramic heater: running at high 1,200 W / low 600 W (typical product specs). Models with a room-temperature sensor that cuts power cost less. Air conditioner: heat needed (6 tatami 16°C ~0.33 kW / 8 tatami 18°C ~0.47 kW / 10 tatami 20°C ~0.67 kW, from Kakaku.com's oil heater estimate — De'Longhi, concrete apartment, early-December Tokyo, 9 hours) divided by ~2.5× (cold day) or ~4.7× (7°C). Unit price 31 yen/kWh (National Fair Trade Council of Household Electric Appliances guideline, revised July 2022). 1 tatami ≈ 1.6 m².
Heat the room with the air conditioner, and add the ceramic heater only when your feet are cold.
Cost of short bursts
To warm a changing room or toilet — places without an air conditioner — for just a few minutes, a ceramic heater's instant warm air is ideal. Japan's Consumer Affairs Agency recommends warming the changing room and bathroom before a bath to prevent winter bathing accidents.
1,200 W × 10 min = 0.2 kWh = about 6.2 yen at 31 yen/kWh.
Which one suits you?
Air conditioner if…
- You want a living room or bedroom warm for hours
- You want the lowest electricity bill
- You want the whole room at a steady temperature
- Your room already has one (most Japanese rentals do)
Ceramic heater if…
- You want to warm the changing room or toilet just before use
- Your feet get cold at your desk
- You need warmth right away while the AC warms up
- You want to carry it from room to room
For how to choose, see our ceramic heater guide.
Using them well, safely
-
AC for the room, ceramic heater for your feet
Warm air from an air conditioner tends to collect near the ceiling, so your feet can stay cold. Point a ceramic heater on low at your feet instead of turning the AC up. -
Choose a motion sensor or off-timer
Leaving a ceramic heater running is what drives the bill up. A sensor that stops it when nobody's there, or an off-timer, prevents that. -
Don't run it with other big appliances
1,200 W is about the same as a microwave or hair dryer. Using them together can trip the breaker. -
Keep it away from things that burn
Not near curtains or laundry, and never for drying clothes. For a changing room, check the manual that the model is OK near water.
Good to know if you live in Japan
-
Buy a heater made for Japan (100V) with the PSE mark
Japan's household power is 100V, and electric heaters must carry the PSE mark. Be careful with very cheap imports. -
Search in Japanese
Ceramic heater is セラミックヒーター; 人感センサー means motion sensor and 脱衣所 means changing room — useful search words. -
Your real price per kWh depends on your contract
We use 31 yen/kWh. Check your bill or your power company's app for your own rate.
Still not sure?
Answer 6 questions and find the heater that's just right for you.