Geyser Electricity Calculator
Calculate electric geyser energy use from actual element-on time, or estimate the energy needed to heat a volume of water. Include heating sessions, usage days, electricity rate and optional standing losses.
Inputs
Count heating time, not the whole time the switch is on.
Optional energy lost while maintaining stored water temperature.
For seasonal use, count only days the appliance runs.
Water-heating energy & cost
Estimated month running cost
30 units (kWh) in 30 usage days| Period | Units (kWh) | Cost |
|---|---|---|
| Usage day | 1 | ₹8.00 |
| Month (30 usage days) | 30 | ₹240.00 |
| Year (365 usage days) | 365 | ₹2,920.00 |
- Energy per heating session
- 0.5 kWh
- Heating time per session
- 15 min
Standing loss is added once per usage day. The water-volume model is an estimate for a resistance heater, not a heat-pump water heater.
Running energy cost only. Fixed charges, taxes, subsidies and utility-specific tariff rules are excluded.
How this calculator works
Count heating time rather than switched-on time
A resistance heating element consumes its rated power while active, but a thermostat can switch it off after reaching temperature. Enter the element-on minutes for one heating session and the number of sessions per operating day.
Estimate heating from water volume
Water-volume mode uses mass × specific heat × temperature rise, assuming approximately 1 kg per litre and water specific heat of 4.184 kJ/(kg·°C). It divides by the entered efficiency to account for heating losses. The indicated heating time follows from the element’s electrical power.
Separate stored-water losses
Additional standing loss is added once per usage day, outside the session calculation. Avoid double-counting it if your measured element-on time already includes reheating. This model is for resistance heaters; heat-pump water heaters need a different efficiency model.
Calculation formulas
Time mode kWh/session = Element W ÷ 1,000 × Element-on minutes ÷ 60Water mode kWh/session = Litres × 4.184 × (Target °C − Inlet °C) ÷ 3,600 ÷ Efficiency fractionDaily kWh = Session kWh × Sessions/day + Additional standing lossWorked example
Illustration: a 2,000 W element on for 15 minutes uses 0.5 kWh per session. Two sessions each day use 1 kWh before standing losses. At an example ₹8/kWh, 30 usage days cost ₹240 in energy charges.
Understanding the estimate
All prefilled powers, usage patterns and rates are editable examples. This tool runs locally in your browser. Energy-only estimates are not complete electricity bills, and comparisons are scenarios rather than guaranteed savings.
Frequently asked questions
Does a geyser use full power whenever its switch is on?
The element uses power while heating, but the thermostat can turn it off. Count actual heating minutes, or use the water-volume model and add estimated standing loss separately.
Does a larger heating element always use more units per tank?
For the same water volume, temperature rise and efficiency, it mainly changes heating time. The energy needed to heat the water stays approximately the same.
What if my target temperature is below the inlet temperature?
The heating model requires a target above the inlet. Correct those temperatures, or use timed heating with zero minutes if no heating is needed. A request requiring over 24 hours of element operation per day is rejected.