Kilowatt-Hour Basics: Watts, Hours, and kWh
A kilowatt-hour (kWh) is the standard retail unit for electricity. This guide connects watts, hours, and bill math without treating a worksheet as your utility invoice.
Watts measure power; kWh measures energy
Watts describe how hard a device is working right now. Multiply average watts by hours of use, then divide by 1000, to get kilowatt-hours: energy over time. A 1000 W heater running one hour uses about 1 kWh.
Educational math, not a utility bill
Providers may bill with tiers, time-of-use periods, demand charges, taxes, and fixed fees. A flat $/kWh worksheet cannot reproduce every tariff clause.
Convert watts to kWh
1
Find running watts
Use the nameplate, meter, or Energy Guide average.
2
Estimate hours
Use a realistic daily average, not a single peak day.
3
Divide by 1000
kWh = (watts × hours) ÷ 1000.
4
Multiply by rate
Cost ≈ kWh × your energy rate ($/kWh).
Why monthly estimates use days
Daily kWh × days in the billing period approximates a month. Leap years and 28–31 day cycles change the scale slightly; the worksheets let you set days per month.