Running energy, standby use, and electricity cost
Power entry adds running and standby energy for your appliance quantity. Measured entry uses the total you supplied for the whole group without multiplying quantity or adding standby again; no running/standby split is inferred. Both use the same average daily energy and your tariff across the selected days.
To estimate backup duration for the same load, use the Battery Runtime Calculator with battery capacity and conversion losses.
The formula
Kilowatts are converted to watts by multiplying by 1,000. Usage is divided by 60 for minutes per day, by 7 for weekly hours, or by 30 for monthly hours. The powered-on percentage reduces running hours only. Standby covers the remaining hours. Prices entered in cents or paise are divided by 100. Power, tariff, schedule and measurement-period unit changes preserve their physical daily equivalent. Measured energy includes the whole group and is never multiplied by quantity or cycling again.
Worked example
A device averaging 1,000 W for two hours daily uses 60 kWh in thirty days. At 2 W standby for the other twenty-two hours, it adds 1.32 kWh. At 0.20 per kWh, the combined cost is 12.264 currency units. The same total is obtained by entering a measured 2.044 kWh per day, or 14.308 kWh per week, with thirty estimated days.
How to use this calculator
- Choose Power and usage or Measured kWh.
- For power entry, choose an example or enter your own electrical power, usage schedule and quantity. Open Standby and cycling for off-state draw and powered-on share.
- For measured entry, enter the energy for the whole appliance or group and its day, week or 30-day-month period.
- Enter your electricity price and currency, choose currency units or cents/paise, and set the days to estimate.
- Results update as you edit. Review the selected-period total and the repeated-average daily, weekly, monthly and yearly comparisons. Reset restores the original example.
Appliance examples are a starting point
The dropdown contains illustrative power values for common appliances, not measurements or current averages for every model. It changes the power input without replacing your hours, price, quantity or standby settings. A plug-in electricity meter or your model’s electrical input label gives a better estimate.
Changing watts manually switches the dropdown back to Enter my own power. Switching between watts and kilowatts preserves the same physical power; switching the price unit preserves the same tariff.
Avoid counting appliance cycling twice
A refrigerator, heater or air conditioner may turn its motor or element on and off while you are using it. Use the full electrical input with a measured powered-on percentage, or enter average power with 100% powered-on time. Reducing both an already averaged power and the cycling percentage underestimates energy.
Cooling capacity in BTU per hour or tons is not electrical input power. Likewise, a microwave’s cooking output or a motor’s mechanical horsepower is not its electricity draw. Use electrical input watts or kilowatts here.
Read the variable part of your electricity bill
Choose the price for each kWh rather than your total bill or a monthly standing charge. For a 20-cent tariff, 0.20 currency units and 20 cents describe the same price. The currency menu labels results; it does not exchange currencies.
Tiered tariffs, time-of-use rates, demand charges and fixed fees need a separate calculation or bill analysis. If your weekly or monthly usage varies, the results average it over 7 or 30 days; a chosen period does not reproduce a detailed calendar schedule.
Use a representative meter reading
Measured kWh avoids guessing the on/off cycle of a refrigerator or thermostat-controlled device. Include the entire appliance or group for the selected measurement period. One week means seven days; a month here means thirty days. A hot summer week, an unusual work schedule or a short test may not represent a whole year. The calculator extrapolates your supplied average rather than correcting seasonal changes.
Assumptions & limitations
What this calculation assumes
- Every appliance entered uses the same power, standby setting and average daily schedule.
- The electricity rate stays constant. Cents and paise are one hundredth of the offered currency unit.
- A month means 30 days and a year means 365 days. Powered-on time is a fraction of entered usage hours.
What to keep in mind
- Appliance presets are editable examples, not manufacturer specifications or measurements.
- Fixed charges, changing tariffs and taxes are excluded unless already included in your effective unit price.
- The cycling setting represents on/off time at the entered power; it does not model a dimmer, speed control, inverter load curve or start-up surge.
- Displays round energy and money, but costs are calculated from unrounded energy.
Common questions
Can I set standby power to zero?
Yes. Do that when the device is unplugged or its off-state draw is negligible for the estimate.
How do I handle a refrigerator?
Use measured average power over a representative period, or enter actual compressor-running hours with the relevant power. Do not assume the rated compressor draw continues all day.
Does the appliance dropdown give my exact power use?
No. It fills an example electrical power value. Change it to your model’s input wattage or measured average power, and enter your own usage.
What does Powered-on time mean?
It is the fraction of your entered usage hours when the appliance draws its stated running power. For 8 usage hours at 50%, running energy uses 4 hours and standby uses the other 20 hours each day. Keep this at 100% if your power value already averages on/off cycles.
Can I use a weekly usage time?
Yes. Select Hours per week. For example, 14 hours per week averages 2 hours per day. Hours per 30-day month divides your total by 30; minutes per day divides by 60. Each schedule must fit within 24 hours per day before cycling.
Does selecting another currency convert the result?
No. Enter the rate in the currency you selected. The menu labels the amounts and does not apply an exchange rate.
Does measured kWh need a quantity or standby adjustment?
No. Enter measured total energy for all appliances being estimated. The meter total already contains their cycling and off-state consumption, so those controls are hidden and do not add to the result.
Sources & further reading
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