Electricity cost calculator: watts and hours

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From electricity use to cost.

Estimated electricity cost

$12.00

for 30 entered use days

Energy in this period: 60 kWh
Cost per use day: $0.40
Energy per use day: 2 kWh
Cost per hour at entered power: $0.20

Your rate, your estimate

This assumes the entered electrical power is drawn throughout the entered use time. A nameplate rating may overstate average use when an appliance cycles.

How we calculate this

1 kW × 2 hours × 30 days = 60 kWh. × $0.20 per kWh = $12.00.

Measured mode divides the measured kWh by complete measurement days, then multiplies by your use days. Electricity only, at a constant entered rate. Fixed charges and other household costs are excluded.

Understand watts, time and cost

Before you calculate

Enter electrical input power, not heat output, cooling capacity or microwave cooking output.
Power mode assumes the entered draw continues throughout your entered time. Use a suitable average or measured energy for appliances that cycle.
Measured mode uses the average of complete measured days. It already includes cycling and any idle use captured in the sample.
Choose the number of use days for your month, season or year. The tool does not assume every appliance runs on all 365 days.
Electricity cost uses a constant entered unit rate. Fixed charges, tariff tiers and other costs are excluded.

Replace every sample figure with one appropriate to your appliance and household.

Sources and product documents

Reading Municipal Light Department: Electricity use and bill calculationsReference checked 2026-10-01
US EIA: Electricity units glossaryReference checked 2026-10-01

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