Geyser Electricity Cost Calculator

How Many Units Does a Geyser Use Per Hour?

One unit on your bill is one kilowatt hour (kWh). So a geyser uses as many units per hour as its wattage in kilowatts, but only while it's actually heating.

The example rate is CESC Kolkata's 151 to 300 unit slab, before duty and other charges. Your rate depends on your state and your slab.

How to Calculate Your Geyser's Electricity Bill

You've probably seen calculators that simply multiply wattage by hours. Let's be honest, that gets it wrong, because nobody's geyser heats for every minute it's switched on. These two methods are far closer to the truth.

Method 1: Time the heating light

Most geysers have a light that glows while the element heats and goes off when the water is ready. That light tells you exactly when you're paying.

Method 2: Count your tanks

Bajaj's manual lists how long each size takes to raise the water temperature by 35°C. Multiply that time by the wattage and you get the units for one full tank.

Then add the heat the tank loses while it stays switched on. We cover that below.

What Does a Geyser Cost Per Month?

Here are quick estimates for heating water only, with the geyser switched off after use. Pick your size and how many full tanks you use a day.

Based on the 35°C rise times above, 30 days and ₹7.62 a unit. Hotter settings and colder water push these numbers up. For your own figure, use the calculator above.

Why Your Geyser Costs More in Winter

It isn't your imagination. Winter hits the geyser from three sides at once. More people use hot water, they use more of it, and the water coming in is colder, so every tank needs more heating.

The manuals show how much the temperature rise matters. Bajaj tests its heaters with a 35°C rise, while Havells tests with a 50°C rise. Heating water by 50°C takes about 43% more units than heating it by 35°C. That's why the calculator asks about each season separately.

Is It Cheaper to Keep the Geyser On All Day?

This is the question that starts arguments in most homes. Here's what the manuals say. Havells notes the heater can be kept on all the time because the tank is insulated and the thermostat keeps the water hot. Bajaj agrees it can stay on, but advises switching it off when not in use to save electricity.

Both are right. The insulation slows the heat loss, but it doesn't stop it. Manuals list this as standing loss: the units a full, hot tank loses over 24 hours.

Figures are measured with the water 45°C hotter than the room, as printed in each manual.

Instant vs Storage Geyser: Which Costs Less to Run?

Planning to buy? This is where the two types really differ.

An instant geyser wastes nothing while it waits, which makes it cheap for small, quick jobs. For a family, a right-sized storage geyser that's switched off after use is the sensible choice.

Does a Bigger Geyser Use More Electricity?

Only if you heat water you don't use. Heating a full 25L tank takes about 1 unit, against about 0.67 for a 15L tank. A bigger tank also loses a little more heat while it stays on, about 0.1 units a day more in the table above.

So the real cost of a too-big geyser is paying to heat water that goes cold before anyone uses it. Not sure which size fits your family? Try our Geyser Size Finder.

Does a 3 kW Geyser Cost More Than a 2 kW One?

Not for the same water. A 3 kW geyser heats faster, so it runs for less time. A. O. Smith's 3 kW Express Heat models raise the water by 35°C in 7 minutes (15L) where its 2 kW models take 12. The units end up about the same. What a higher wattage does change is the load on your wiring, which is why it needs a 16A socket and a suitable MCB.

How to Reduce Geyser Power Consumption: 12 Simple Ways

You don't need a new geyser to cut the bill. Most of these cost nothing at all.

Change How You Use It (Free)

1. Switch it off after heating

A 15L geyser left on all day loses around 0.4 to 0.46 units a day just staying hot. Switching it off once the water is ready saves most of that.

2. Use Eco mode or a medium setting

Many geysers leave the factory set to 75°C. Havells Magnatron switches to Eco mode at 55°C or below, which it says saves power and time. Don't go too low though. A. O. Smith recommends keeping the knob at medium or above.

3. Bathe one after another

One hot tank for the whole family costs less than heating the geyser three separate times and keeping it on in between.

4. Heat only what you need

Every extra tank is another 0.4 to 1.8 units, depending on size. If one tank covers your mornings, there's no need for a second.

5. Switch it off in the warm months

Bajaj, Havells and Symphony all advise switching off the power and draining the tank when the geyser won't be used for a long time.

6. Use auto-off or smart controls

Symphony's auto-off timer switches the geyser off if hot water sits unused for 2 hours. Havells' smart Monza Slim i has a scheduler in its app that turns the geyser on and off automatically at the times you choose.

Look After Your Geyser (Low Cost)

7. Descale it once a year

Scale on the heating element acts like a blanket, so the geyser takes longer to heat the same water. Havells and Symphony both recommend descaling once a year, and more often in hard water areas. Our blog has a step-by-step guide on cleaning a geyser tank.

8. Lower the thermostat a little in hard water areas

Bajaj notes that scaling happens more in hard water, and a slightly lower thermostat setting helps reduce it. Less scale means faster heating.

9. Flush the tank after winter

Draining and flushing the tank removes sediment that settles at the bottom and slows heating. Always have this done safely, with the power off.

10. Get a yearly service

Havells asks for the heating element to be checked every year for scale. A yearly service also catches a worn anode rod, a tired thermostat or a small leak before they cost you more.

Set It Up Right (When Buying)

11. Pick the right size

A tank that's too big heats water nobody uses. Our Geyser Size Finder takes less than a minute.

12. Compare standing loss before you buy

Good insulation keeps heat in. Most manuals print the standing loss figure, so compare it between models of the same size. Lower is better, especially if you keep the geyser on for long hours.

Bill Higher Than the Calculator Says?

If your real bill is much higher than the estimate, your geyser may be wasting power. Watch for these signs:

• Water takes much longer to heat than it used to.
• The heating light stays on far longer than it should.
• Popping, rumbling or humming sounds while it heats, often a sign of scale.
• The water comes out too hot, so the thermostat may not be cutting off.
• The MCB trips again and again.
• Water leaks from the geyser or its connections.

These usually point to scale, a faulty thermostat or a weak heating element. A check-up costs far less than months of wasted units. Our technicians cover Kolkata, Howrah, Barasat and Barrackpore.

Save Power, but Never at the Cost of Safety