Room heater electricity cost: what each heater type really uses

Your room heater electricity cost comes down to one fact: a room heater uses exactly as many units as its wattage says, for as long as its element is on. A 2,000 W heater running flat out uses 2 units (kWh) every hour, whether it is a fan heater, a halogen heater or an oil-filled radiator. The heater type changes how the warmth reaches you, how fast it arrives and how safe it is around children — not how much heat you get from each unit. What actually lowers your bill is a lower heat setting, a working thermostat, a smaller closed room and fewer hours.

That matters right now, because November is when north Indian homes switch heaters on and the first big bill arrives a month later. Here is the simple maths, what each type is good at, and what to check before you buy.

The one formula you need

Units used = wattage ÷ 1,000 × hours of use.

Your electricity bill counts "units", and one unit is one kilowatt-hour (kWh). So:

• An 800 W setting for 1 hour = 0.8 units
• A 2,000 W heater for 1 hour = 2 units
• A 2,000 W heater for 5 hours = 10 units

Multiply the units by your per-unit rate (printed on your electricity bill) and you have the cost. Because almost all of the electricity an electric heater draws ends up as heat in the room, a "high-efficiency" claim on an ordinary room heater usually means better heat distribution or control, not more warmth per unit.

Monthly cost at full power

The table assumes 4 hours a day for 30 days at full power. Real use is often lower because a thermostat switches the element off once the room is warm, so treat these as the upper limit. The ₹6 and ₹8 per unit columns are round example rates, not any particular state's tariff.

Two things the table does not show:

• Slab tariffs. Most Indian discoms charge more per unit as your monthly use goes up, so heater units are often billed at your highest slab. In Delhi, for example, the first 200 units a month are subsidised for households that opt in, and the energy charge rises in steps above that (Housing.com's summary of Delhi rates). A heater that adds 150–250 units can move a home out of a cheap or free band. Check the slab table on your own bill.
• Fixed charges. These depend on your sanctioned load, not on the heater, unless the heater pushes you to raise that load.

Fan, halogen and oil-filled: what actually differs

All three are electric heaters. The differences are speed, comfort and safety.

Fan heaters (including PTC/ceramic)

A fan blows air over a hot element. They warm the air near you quickly and are cheap to buy — Croma notes electric heaters start from around ₹1,000 and can heat a room "within seconds" (Croma). Bajaj Electricals describes fan heaters as convenient for warming a space in a short time (Bajaj Electricals). The trade-offs: fan noise, and the warmth fades soon after you switch off.

Best for: short bursts — warming a room before bed, a bathroom before a bath, a study for an hour.

Halogen and other radiant heaters

These heat whatever they face — you, a chair — rather than the whole room's air. That makes them feel warm almost instantly at close range. Bajaj points out that their surface heats up fast and calls them unsuitable around children, and suggests them for small spaces (Bajaj Electricals).

Best for: one person sitting in one spot, with no small children or pets around.

Oil-filled radiators (OFR)

Electricity heats sealed oil inside the fins, which then warm the room slowly and evenly. Croma says they can take 20–30 minutes to warm a room, have no exposed glowing element, run silently and do not dry out the air, and they keep giving off heat after switching off; better models can cost over ₹10,000 (Croma).

The money advantage of an OFR is not magic efficiency. It comes from two things: most models have a thermostat that cycles the element off once the room is warm, and the stored heat in the oil keeps the room comfortable during those off periods. If you run an OFR on its highest setting all night in a draughty room, it will cost the same as any other heater of that wattage.

Best for: long evenings and overnight warmth in a closed bedroom, homes with babies or elderly people.

Read the wattage settings, not just the headline number

Many heaters list one big number on the box, but the settings tell you what you will actually pay for. Two examples from Havells' own product pages:

• The Havells Hestio 9 Wave Fin OFR lists settings of 800 W, 1,200 W and 2,000 W, plus a 400 W PTC fan heater — which is where the "2,400 W" figure comes from (Havells).
• The Havells Vlamo-i 10 Fin lists Low 1,000 W, Medium 1,500 W and High 2,500 W, with an adjustable thermostat and a timer (Havells).

On a heater like the first one, running on the 800 W setting instead of everything-on 2,400 W uses one-third of the units per hour. A higher maximum wattage is useful to warm a cold room quickly; it is not what you should leave running for hours.

Five ways to cut the heater bill

1. Warm up on high, then drop to low. Use the top setting for the first 15–30 minutes, then switch to the lowest setting that keeps you comfortable.
2. Use the thermostat. A heater that switches itself off when the room reaches your chosen temperature spends fewer hours at full power. Without one, it runs at full wattage the whole time.
3. Heat a smaller, closed room. Close the door and curtains. Heating a large hall or an open-plan room for one person wastes units.
4. Use the timer. If you run a heater while falling asleep, set it to switch off after an hour or two (an OFR keeps the room warm for a while after).
5. Do the maths for your own bill. Note your meter reading on two days a week apart, with and without the heater, and you will see its real cost at your slab rate.

Safety checks that matter more than the bill

Safety is a bigger decision than a few hundred rupees a month.

• Look for the ISI mark. Bajaj Electricals advises buying ISI-approved heaters (Bajaj Electricals). Our explainer on BIS, ISI and star labels shows how to check a licence.
• Tip-over switch and overheat cut-off. Both Havells models above list a tip-over switch and overheat or thermal cut-out protection. These switch the heater off if it falls or gets too hot.
• Keep space around it. Bajaj advises keeping heaters at least 2 feet from furniture, bedding, clothes and rugs, on a hard, level surface.
• Plug into a proper wall socket. A 2,000 W+ heater draws a heavy current. Avoid cheap multi-plugs and thin extension cords that can overheat.
• Never use a coal angithi in a closed room. It is not an electric heater, but it causes deaths every winter. In January 2024 alone, 15 people in Delhi died after inhaling angithi smoke, according to the Delhi Fire Service director quoted by IANS; in one case a family of four was found in a room locked from inside with a brazier (The Tribune). The fire service advice was to keep a window or door slightly open whenever anything is burning or heating in a closed room.

Which one should you buy?

When you shop, compare the actual setting wattages, the thermostat and timer, the safety cut-offs and the warranty — then compare prices. You can browse current appliance offers on our large appliances deals page and check how a listed price has moved with the Deals Basket price tracker. If you are also weighing cooking costs this winter, our induction vs LPG cost comparison uses the same units-times-rate method.