Find the electricity units (kWh) an appliance uses.
Converts power and time into kilowatt-hours, the standard billing unit for electricity.
Units: (Power in watts ÷ 1000) × hours
The electricity unit calculator converts an appliance's power in watts and its running time in hours into units, the kilowatt-hours printed on every Indian electricity bill. It answers one simple question: how much energy did this appliance use?
Counting units is the first step in making sense of a bill. Once you know that a ceiling fan uses less than a unit a day while an AC uses several units an hour, you can see where savings are possible. The calculator helps students learning about power and energy, households checking a meter reading, solar buyers sizing a system from their daily units, and people choosing between star-rated appliances by their energy use.
1. Read the appliance's power rating in watts from its label.
2. Note how many hours it runs.
3. Convert watts to kilowatts by dividing by 1000.
4. Units (kWh) = Kilowatts × Hours.
5. For daily or monthly units, multiply by the number of days.
6. If the label gives amps instead of watts, estimate watts as volts × amps, using about 230 V for Indian household supply.
One unit is one kilowatt-hour, the energy used when 1000 watts flow for one hour. The same unit is used by a 100 W bulb in 10 hours, by a 75 W fan in about 13.3 hours, or by a 1500 W AC in 40 minutes. The watt is a rate, like km/h, while the kWh is an amount, like km. Confusing the two is common: a 1 kW appliance does not use '1 unit' until it has run for a full hour.
Some appliances list current in amperes rather than power. For resistive loads such as heaters, irons and geysers, power is roughly voltage × current, so a 6 A heater on a 230 V supply draws about 1380 W. Motors and electronics have a power factor below one, so the real power is somewhat less than volts × amps. For these, the watt figure on the label or a plug-in energy meter reading is more reliable.
BEE star labels on many Indian appliances, such as refrigerators and ACs, state an estimated annual energy use in units under standard test conditions. Dividing by 365 gives a rough daily figure to compare with this calculator's result. Your electricity meter counts cumulative units, so reading it before and after running one appliance, with everything else off, is a practical way to measure real consumption and check the estimate.
Arun wants to know how many units his 75 W ceiling fan uses on a hot day in Nagpur when it runs for 12 hours straight.
Answer: Units consumed 0.9 kWh
Treating watts and units as the same thing, when units also depend on running time.
Forgetting to divide by 1000, which inflates the answer a thousand times.
Using volts × amps for motors and electronic devices, which overstates their real power.
Ignoring standby consumption of set-top boxes, chargers and microwaves left plugged in.
Estimating each appliance's share of the monthly bill.
Sizing a solar panel or inverter battery from daily units.
Comparing star-rated appliances by annual energy use.
Solving power and energy problems in school physics.
How many units does a typical AC use per hour?
It depends on the AC's size and star rating, but a 1.5-ton AC often uses about 1-1.5 units per hour. Check your own appliance's rated power for an exact figure.