Electricity Bill Calculator
One appliance's monthly running cost, from its power rating and how many hours a day it's actually used — the number that reveals whether that always-on device is a minor cost or a real budget line.
Inputs
Result
2,160
270 kWh per month
How the electricity bill calculator works
Monthly energy = (power rating in watts ÷ 1,000) × hours per day × 30 days, giving kWh.
Monthly cost = kWh × tariff rate per kWh.
Worked example: 1,500 W appliance, 6 hours/day, tariff 8 per kWh
- kWh = (1,500 ÷ 1,000) × 6 × 30 = 1.5 × 6 × 30 = 270 kWh per month.
- Cost = 270 × 8 = 2,160 per month.
Common mistakes to avoid
Using an appliance's peak power draw instead of its typical running power
Many appliances (like air conditioners and refrigerators) cycle on and off rather than drawing their rated wattage continuously — using peak wattage as if it were constant significantly overstates real energy use.
Assuming a flat 30-day month always
This calculator uses 30 days as a standard approximation — for a precise monthly bill matching a specific calendar month (28-31 days), adjust proportionally.
Frequently asked questions
How do I find an appliance's actual power rating?
Check the nameplate or manual, usually listed in watts (W) — for appliances that cycle (fridges, AC units), this rated figure is typically the peak, not the continuous average draw.
Why is the result divided by 1,000 in the formula?
Power ratings are given in watts, but electricity is billed in kilowatt-hours — dividing by 1,000 converts watts to kilowatts before multiplying by hours to get kWh.
How can I use this to compare two appliances' running costs?
Run the calculation separately for each appliance's wattage and typical daily hours, then compare the monthly cost figures directly.
Does tariff rate ever change based on how much electricity is used?
In many regions, yes — tiered or slab-based tariffs charge a higher rate once usage crosses certain thresholds. This calculator assumes one flat rate throughout, a simplification for tiered billing structures.
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