Electricity Cost Calculator
Results
0.5 kWh
per day
£0.15
per day
£4.5
per month (30 days)
£54.75
per year (365 days)
Note: Costs vary by tariff, time-of-use pricing, standing charges, and actual appliance power draw. This is an estimate.
Quick Facts
- •kWh = (Watts ÷ 1000) × hours
- •Cost = kWh × tariff per kWh
- •100W bulb for 10 hours = 1 kWh
- •A 2kW heater costs about £0.60/hr at £0.30/kWh
Formula
First convert watts to kilowatts, multiply by usage hours to get kWh, then multiply by your electricity rate.
Worked Examples
100W bulb, 5 hours/day, £0.30/kWh →
(100 ÷ 1000) × 5 = 0.5 kWh/day × £0.30 = £0.15/day = £4.50/month
2kW heater, 3 hours/day, £0.30/kWh →
2 × 3 = 6 kWh/day × £0.30 = £1.80/day = £54/month
500W fridge, 24 hours/day, $0.12/kWh →
(500 ÷ 1000) × 24 = 12 kWh/day × $0.12 = $1.44/day = $43.20/month
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Frequently Asked Questions
How do I calculate electricity cost?
Cost = (Watts ÷ 1000) × hours × tariff per kWh. For example, a 100W bulb for 10 hours at £0.30/kWh = 0.3 kWh × £0.30 = £0.09.
What is a kilowatt-hour (kWh)?
The energy consumed by a 1,000-watt appliance running for 1 hour. It's the standard unit on electricity bills.
How much does it cost to run a heater?
A 2 kW heater for 3 hours/day at £0.30/kWh costs 2 × 3 × 0.30 = £1.80/day, about £54/month.
What uses the most electricity at home?
Typically: heating/cooling, water heater, washer/dryer, oven, and EV charging.
How can I reduce electricity costs?
Use energy-efficient appliances, LED bulbs, smart thermostats, and run appliances during off-peak hours.
Are these costs exact?
No. Actual costs vary by tariff, time-of-use pricing, standing charges, and real appliance power draw.