Energy Consumption Calculator

Step-by-Step Guide

1. 1Add an Appliance: Click add appliance, or choose from built-in presets covering lighting, cooling, kitchen, and entertainment devices with typical wattage pre-filled.
2. 2Enter Power Rating: Type the appliance's wattage from its nameplate or manual, or use the auto-filled preset value.
3. 3Set Daily Usage Time: Enter hours and minutes of typical daily use, plus quantity if you have more than one of the same device.
4. 4Enter Your Electricity Rate: Input your cost per kWh from a recent electricity bill so the cost estimate matches your actual utility pricing.
5. 5Review Daily, Monthly, and Yearly Totals: The results panel shows combined energy in kWh and cost across all appliances, plus the largest single contributor.

What This Calculator Provides

• ✓Real-time calculation as you type
• ✓Unlimited appliances tracked at once
• ✓28 built-in appliance presets with typical wattage
• ✓Daily, monthly, and yearly energy and cost totals
• ✓Highest-consumer detection across your appliance list
• ✓Calculation history
• ✓CSV export for spreadsheets
• ✓Text export for reports
• ✓Private: your inputs are not collected or stored
• ✓No signup required

Pro Tips

• 💡Use a plug-in power meter for compressor-based appliances (fridges, ACs, heat pumps) instead of the nameplate wattage. These devices cycle on and off, so their average draw is often 30-50% below the rated figure printed on the label.
• 💡Enter standby devices separately from active-use devices. A router or set-top box running 24 hours a day at just 10W still adds up to 7.3 kWh a month — small individually, but a household with a dozen such devices can lose $30-50 a year to phantom load.
• 💡Check your bill for tiered or time-of-use pricing before entering a single flat rate. If your utility charges more per kWh above a usage threshold, or charges different peak/off-peak rates, calculate high-usage appliances at the marginal rate that actually applies to them.
• 💡Save a baseline calculation to history before making an efficiency change (like an LED retrofit or a thermostat adjustment), then create a second calculation with the new numbers so you can compare the exact dollar difference side by side.
• 💡Export to CSV when auditing more than a handful of appliances — it's far easier to sort, filter, and chart in a spreadsheet than to read through a long list of individual result cards on screen.

Common Mistakes to Avoid

• ✕Entering power in kilowatts but leaving the field labeled as watts, or vice versa. A 1.5kW heater entered as "1.5" instead of "1500" understates energy use by a factor of 1,000 — always convert kW to W by multiplying by 1,000 first.
• ✕Forgetting to set the electricity rate, or leaving the default placeholder value in place. The energy figure in kWh is accurate regardless, but the cost estimate is meaningless unless the rate matches your actual utility pricing.
• ✕Using nameplate maximum wattage for devices with variable draw, like a laptop charger or a variable-speed motor. These often run well below their rated peak most of the time, so a nameplate-based estimate can overstate real cost.
• ✕Comparing this calculator's total directly against your electricity bill without accounting for fixed service charges, taxes, and appliances you didn't include. The calculator estimates only the variable energy cost of the specific devices you enter.
• ✕Ignoring quantity when multiple identical devices are in use. Four 10W LED bulbs used together is 40W of combined load, not 10W — always set the quantity field rather than entering a single unit and forgetting the rest.