This free home energy usage calculator adds up the electricity used by every appliance in your house — lights, fridge, TV, air conditioning, heating, water heater, dryer and EV charging — to show your kWh per day and per month, your estimated electric bill and which appliances use the most power. Use it to understand a high bill, plan energy savings, or work out how much solar or battery storage your home needs.
How home energy use is calculated
kWh per month (each appliance) = watts × hours per day × quantity × 30.4 ÷ 1000
Total kWh = sum of all appliances
Monthly cost = total kWh × price per kWh
Worked example
The default list — ten LED bulbs, a fridge, TV, Wi-Fi router, laptop, ceiling fan, microwave and washing machine — adds up to about 116 kWh a month. At $0.17 per kWh that is about $19.78 a month. Add a central air conditioner running 6 hours a day and the total rises by 639 kWh — more than everything else combined.
Monthly energy use of common appliances
Typical usage for one of each appliance, sorted from highest to lowest, at $0.17 per kWh.
| Appliance | Watts | Hours / day | kWh / month | Cost / month |
|---|---|---|---|---|
| Central AC | 3,500 W | 6 | 638.8 | $108.59 |
| Window / room AC | 1,000 W | 8 | 243.3 | $41.37 |
| Electric water heater | 4,000 W | 2 | 243.3 | $41.37 |
| EV charging (Level 2) | 7,200 W | 1 | 219 | $37.23 |
| Space heater | 1,500 W | 4 | 182.5 | $31.03 |
| Dishwasher | 1,800 W | 1 | 54.8 | $9.31 |
| Clothes dryer (electric) | 3,000 W | 0.5 | 45.6 | $7.76 |
| Refrigerator | 150 W | 8 | 36.5 | $6.21 |
| Desktop / gaming PC | 300 W | 3 | 27.4 | $4.65 |
| Ceiling fan | 75 W | 8 | 18.3 | $3.10 |
| TV | 100 W | 4 | 12.2 | $2.07 |
| Laptop | 60 W | 6 | 11 | $1.86 |
| Microwave | 1,100 W | 0.25 | 8.4 | $1.42 |
| Washing machine | 500 W | 0.5 | 7.6 | $1.29 |
| Wi-Fi router | 10 W | 24 | 7.3 | $1.24 |
| LED light bulbs | 10 W | 5 | 1.5 | $0.259 |
How to reduce your home energy use
- Start with the biggest loads. A small change to heating, cooling or water heating saves more than switching off every light.
- Right-size your air conditioner. An oversized unit cycles on and off and wastes energy — check with the AC BTU calculator.
- Shift flexible loads. On a time-of-use tariff, run the dryer, dishwasher and EV charging off-peak.
- Check single appliances with the electricity cost calculator.
- Consider solar. Once you know your monthly kWh, the solar panel calculator sizes a system to cover it.