Which mode should I use?

Use total_kwh when you already know monthly usage from a bill. Use appliances to build a bottom-up estimate.

Are zero slots counted?

Slots with both watts and hours at zero do not add energy. Any non-zero watts or hours increments the appliance count.

Home Energy Usage Calculator

Estimate household electricity use and cost from a monthly kWh total or up to three appliance loads sharing one rate.

Total or multi-load

Shared rate

Day / month / year

Either prices a monthly kWh total or sums up to three watt×hour loads, then applies your rate for day, month, and year costs.

Limitation: Educational estimate only.

Jump to calculator · Sources & review

CurrencyInput modeElectricity rate ($/kWh)Days per monthMonthly kWh (total_kwh mode)Appliance 1 wattsAppliance 1 hours/dayAppliance 2 wattsAppliance 2 hours/dayAppliance 3 wattsAppliance 3 hours/day

How to Use the Home Energy Usage Calculator

Enter the fields below, then review kWh and cost outputs.

Pick appliances mode or monthly kWh mode.

Unused appliance slots

Leave watts and hours at 0 for unused slots. They do not add energy.

What This Calculator Estimates

Combines either a bill-like monthly kWh total or up to three discrete loads under one flat rate.

Worked Examples

Two loads

Inputs

mode:appliances

ratePerKwh:0.2

daysPerMonth:30

watts1:1000

hoursPerDay1:5

watts2:500

hoursPerDay2:2

watts3:0

hoursPerDay3:0

Estimated cost

$36.00 per month

6 kWh/day × 0.20 = 1.20/day; × 30 = 36.

Bill total mode

Inputs

mode:total_kwh

monthlyKwh:600

ratePerKwh:0.1

daysPerMonth:30

Estimated cost

$60.00 per month

600 kWh × 0.10 = 60.

Compare to your bill

If estimates diverge from billed kWh, check hours, duty cycle, and whether your rate is tiered or time-of-use.

Frequently Asked Questions

Schema-driven forms use fixed fields. Run the worksheet multiple times or use the generic appliance calculator for more devices.

Still have questions about this calculation?

Try the Calculator

Formulas & Assumptions

Transparent arithmetic from user-entered inputs. No live utility tariffs are loaded.

Formula

Σ (wattsᵢ ÷ 1000 × hoursᵢ)

Appliances daily kWh

Σ (wattsᵢ ÷ 1000 × hoursᵢ)

Total kWh mode

kWh/day = monthlyKwh ÷ daysPerMonth

Cost

kWh × ratePerKwh

Scientific Background

Educational aggregation only. Whole-home meters, phantom loads, and HVAC diversity are not simulated.

Sources & review

Home Energy Usage Calculator documents the references behind its formulas and assumptions. Always treat results as educational estimates, not personalized professional advice.

Last reviewed

July 22, 2026

Reference
energy.gov
https://www.energy.gov/energysaver/estimating-appliance-and-home-electronic-energy-use
Reference
eia.gov
https://www.eia.gov/energyexplained/units-and-calculators/energy-conversion-calculators.php
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