Energy Usage Calculator

Q: How do I calculate energy usage in kWh?

kWh = Watts × Hours ÷ 1000. For example, a 1,500W heater running for 4 hours: 1,500 × 4 ÷ 1,000 = 6 kWh. Multiply by your rate for cost.

Q: How many kWh does 1000 watts use per hour?

1,000 watts for 1 hour = 1 kWh (one kilowatt-hour). This is the fundamental unit of electricity billing. A 100W bulb running for 10 hours also uses 1 kWh.

Q: What uses 1 kWh of electricity?

1 kWh is enough to: run a 100W light bulb for 10 hours, watch TV (100W) for 10 hours, run a laptop (50W) for 20 hours, or run a 1,000W microwave for 60 minutes.

Convert watts and hours of use into kWh and find the running cost of any electrical device. Get daily, monthly, and annual cost estimates in your currency.

Calculate Energy Usage

Power (Watts)

Daily Use (hours)

Currency

Rate per kWh

Energy Usage Results

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Daily kWh

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Monthly kWh

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Annual kWh

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Daily Cost

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Monthly Cost

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Annual Cost

Formula

kWh per day = Watts × Hours ÷ 1000
Monthly kWh = kWh/day × 30
Annual kWh = kWh/day × 365
Cost = kWh × Rate

Example Calculations

Electric heater (1,500W), 6 hours/day, $0.15/kWh:

Daily kWh = 1,500 × 6 ÷ 1,000 = 9 kWh
Monthly = 9 × 30 = 270 kWh = $40.50/month

LED TV (100W), 5 hours/day, $0.15/kWh:

Daily kWh = 100 × 5 ÷ 1,000 = 0.5 kWh
Monthly = 0.5 × 30 = 15 kWh = $2.25/month

Understanding kWh

A kilowatt-hour (kWh) is the standard unit of electrical energy used for billing. It equals 1,000 watts running for 1 hour — or any combination that multiplies to 1,000 Wh.

1 kWh = 1,000W × 1 hour = 500W × 2 hours = 100W × 10 hours
Your electricity meter measures in kWh — your bill multiplies total kWh by the rate.
Energy labels on appliances (A+++, etc.) show annual kWh consumption under standard test conditions.
A typical UK home uses 8–12 kWh/day. A typical US home: 25–35 kWh/day.

Frequently Asked Questions

How do I calculate energy usage in kWh?

kWh = Watts × Hours ÷ 1,000. If your appliance shows amps instead of watts: Watts = Amps × Volts. For example, a 10A appliance on 230V = 2,300W. Running it for 2 hours = 4.6 kWh.

How many kWh does 1000 watts use per hour?

Exactly 1 kWh. This is the definition: 1 kilowatt (1,000 watts) for 1 hour = 1 kilowatt-hour. A 2,000W appliance uses 2 kWh per hour. A 500W appliance uses 0.5 kWh per hour.

What uses 1 kWh of electricity?

Common 1 kWh equivalents: a 100W bulb for 10 hours, a laptop (50W) for 20 hours, a 1kW kettle for 60 minutes, a 250W TV for 4 hours, or a 2,500W tumble dryer for 24 minutes. At $0.15/kWh, 1 kWh costs 15 cents — very cheap individually, but significant when multiplied over many appliances daily.