Understanding how much energy your equipment or appliances consume each year helps you manage costs, plan for solar installations, or size backup systems effectively.
This guide explains how to convert kilowatts (kW) into kilowatt-hours per year (kWh/year) – plus includes a free interactive calculator to estimate annual energy consumption and cost.
Table of Contents
Use this calculator to find out your device’s yearly energy use and estimated electricity cost.
🔋 What’s the Difference Between kW and kWh?
| Term | Meaning | Example |
|---|---|---|
| kW (Kilowatt) | Power — how fast energy is used at a moment in time | A 2 kW heater uses 2,000 watts of power |
| kWh (Kilowatt-hour) | Energy — total power used over time | A 2 kW heater running for 3 hours uses 6 kWh |
To get kWh per year, you multiply power (kW) by usage time (hours per year).
⚙️ Formula to Convert kW to kWh Per Year
The conversion is simple:
kWh/year = kW × Hours per Day × Days per YearExample:
If a 2 kW device runs 5 hours per day:
kWh/year = 2 × 5 × 365 = 3,650 kWh/yearIf your electricity rate is $0.15 per kWh:
Annual Cost = 3,650 × 0.15 = $547.50💡 Common Values
| Appliance | Power (kW) | Hours/Day | kWh/Year | Cost/Year (@ $0.15/kWh) |
|---|---|---|---|---|
| Refrigerator | 0.15 | 24 | 1,314 | $197 |
| Air Conditioner | 2.0 | 6 | 4,380 | $657 |
| Water Heater | 3.0 | 2 | 2,190 | $329 |
| Washing Machine | 0.5 | 1 | 183 | $27 |
| Light Bulb (LED) | 0.01 | 5 | 18 | $2.70 |
🧾 Example Scenarios
| Scenario | Power (kW) | Usage (Hours/Day) | Annual Energy (kWh) | Cost ($0.15/kWh) |
|---|---|---|---|---|
| Home Office | 0.4 | 8 | 1,168 | $175 |
| EV Charger | 7.0 | 2 | 5,110 | $766 |
| Pool Pump | 1.2 | 10 | 4,380 | $657 |
| Solar Panel Output | 5.0 | 5 | 9,125 | — (savings) |
🌍 Why It Matters
Understanding kW → kWh per year helps you:
- Estimate electricity bills accurately
- Plan solar system sizes
- Manage energy efficiency goals
- Compare appliance energy ratings
🧮 Summary
| Formula | Meaning |
|---|---|
kWh/year = kW × Hours/Day × Days/Year | Annual energy consumption |
Annual Cost = kWh/year × Rate | Estimated energy cost |
Example:
A 2 kW appliance used 4 hours/day for 365 days →2 × 4 × 365 = 2,920 kWh/year
At $0.15/kWh → $438/year
