Energy Consumption Calculator

What this calculator does

The Energy Consumption Calculator provides fast estimates using standard electrical relationships. Enter Power Rating, Usage Time, Days to compute results for real-world electrical scenarios. Use it for quick checks, comparisons, and documentation while planning.

Inputs explained

  • Power Rating: Power value as labeled (W, kW, VA, or kVA).
  • Usage Time: Hours per day the appliance operates.
  • Days: Number of days in the calculation period.

How it works / Method

The calculator applies the listed formulas to the values you enter and then formats the result in standard units. Energy is computed from power over time, then cost is derived from the selected rate.

Formulas used

  • E = P x t / 1000

Units: P in watts (W) t in hours (h) unless noted

📊

Energy Consumption Calculator

Calculate electricity usage in kWh

W
hrs/day
days
Result
—

Formula

kWhE = P × t / 1000

Where P = watts, t = hours

Common Appliances

Appliance kWh/day
Refrigerator 1-2
AC (window) 3-5
TV (4 hrs) 0.4
Washing machine 0.5

Related

Electricity BillkW to kWhWatts to kWh

Step-by-step example

Scenario: A 100W LED TV runs 6 hours daily for 30 days.

Formula: Energy (kWh) = (Power x Hours x Days) / 1000

  1. Energy = (100 x 6 x 30) / 1000
  2. Energy = 18,000 / 1000
  3. Energy = 18 kWh

Result: 18 kWh per month

Use cases

  • Estimate monthly or yearly energy use in kWh.
  • Approximate operating cost from a utility rate.
  • Compare appliance usage scenarios and schedules.
  • Create budget-level forecasts for energy consumption.

Assumptions & limitations

  • Results are estimates and may be rounded; small differences are expected.
  • Inputs assume steady-state values; transient and surge effects are not modeled.
  • Voltage can vary by supply, load, and location; use measured values when possible.
  • Power factor varies by load type; use a realistic value for inductive equipment.
  • Wiring rules and safety codes vary by jurisdiction; consult a licensed electrician for installation decisions.

Sources & references

Related calculators

Frequently Asked Questions

The Energy Consumption Calculator estimates energy use or cost from your inputs. It is intended for quick planning and comparisons. Results depend on power, time, and rate accuracy. Use it to explore different usage scenarios. This is not a substitute for utility billing data. This calculator is intended for planning and comparison, not for final engineering approval. This calculator is intended for planning and comparison, not for final engineering approval.

Energy in kWh equals power in kW multiplied by hours. Convert watts to kW by dividing by 1000. Then multiply by the time period in hours. The calculator follows this relationship directly. Check that your time input matches the intended period. This calculator is intended for planning and comparison, not for final engineering approval. This calculator is intended for planning and comparison, not for final engineering approval.

Use the rate shown on your utility bill in $/kWh. If you have a tiered or time-of-use plan, use an average. Run multiple scenarios to reflect peak and off-peak rates. The calculator does not model demand charges. Consult your provider for detailed billing rules. This calculator is intended for planning and comparison, not for final engineering approval.

Only if you include those effects in your inputs. For cycling loads, use an average power value. For standby power, add that level and runtime separately. The calculator assumes steady average usage. Adjust inputs to reflect real operating patterns. This calculator is intended for planning and comparison, not for final engineering approval. This calculator is intended for planning and comparison, not for final engineering approval.

Accuracy depends on your input data and usage assumptions. Appliance duty cycles and temperature can change power draw. Use measured values if you need better precision. Treat the result as an estimate for planning. Validate with an energy monitor when needed. This calculator is intended for planning and comparison, not for final engineering approval. This calculator is intended for planning and comparison, not for final engineering approval.

No. This tool is for planning only. Utility bills include metering, tariffs, and demand charges. Those rules vary by provider and location. Use official utility data for disputes or audits. Consult a professional for compliance needs. This calculator is intended for planning and comparison, not for final engineering approval. This calculator is intended for planning and comparison, not for final engineering approval.