Energy consumption calculator (kWh & cost)
Find out how much each appliance adds to your electricity bill, in kWh and money. Example: a 1,000 W air conditioner running 8 h a day uses 240 kWh a month.
The kWh rate varies by utility; check your power bill.
How the calculation works
Your power bill is charged per kWh (kilowatt-hour) — energy used over time. To find an appliance's cost:
kWh = (power in W ÷ 1000) × hours per day × days
cost = kWh × price per kWh
Step-by-step example
A 1,400 W AC, 8 h/day for 30 days, at R$0.90/kWh:
- kWh: (1400 ÷ 1000) × 8 × 30 = 336 kWh
- Cost: 336 × 0.90 = R$302.40/month
The big consumers
Appliances that heat or cool draw the most: electric shower, AC, iron, dryer. A 10 W LED costs pennies; a 5,500 W shower adds up in minutes.
Examples
- Fridge 150 W running 24h/day for 30 days: ~108 kWh.
- A 10 W LED, 5 h/day for 30 days: 1.5 kWh.
Frequently asked questions
Where is the appliance power?
On the product label or manual, in watts (W).
What is the price per kWh?
It is on your bill (tariff + taxes + flag). It varies by region and utility — use your bill's value.
Does standby use energy?
Yes, a little ("phantom load"). TVs, microwaves and plugged-in chargers draw a few watts even off.
Which tariff should I use?
The most accurate is to divide the total bill by the kWh consumed that month — it already includes taxes, distribution charges and the tariff flag.
What weighs most on an electricity bill?
It depends on climate. In summer, usually air conditioning: 1,000 W for 8 hours is 240 kWh a month. Electric showers draw far more power but run only minutes a day.
Is there a minimum charge with no consumption?
Yes, an availability charge: 30 kWh for single-phase, 50 for two-phase and 100 for three-phase connections.
Where do I find an appliance's power rating?
On the manufacturer label, the manual or the Inmetro energy label, which also gives estimated monthly kWh.
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Updated on June 17, 2026 · by Rafael Rossi · Methodology & sources