Determine power
The appliance uses 300 watts, or 0.3 kW.
Guide
How to save electricity costs: find power-hungry devices
Many households pay too much for electricity because they do not properly check usage, runtime and tariffs. Even small mistakes can cost over €100 per year. This guide shows the biggest levers, which actions are worth it and when you should act.
Quick answer
Quick answer: where can you save the most?
You usually save the most by checking large consumers and always-on devices first, reducing standby usage next and then reviewing your electricity tariff. At 3,500 kWh per year, 10% less usage saves about €122 per year, while 20% saves about €245.
Example
Example calculation: using 300 watts for 4 hours per day
The key formula is simple: power in kW × runtime × electricity price. This lets you estimate individual appliances realistically.
Device power300 watts = 0.3 kW
Daily runtime4 hours
Daily usage0.3 kW × 4 h = 1.2 kWh
Yearly usage1.2 kWh × 365 = 438 kWh
Electricity price€0.35 per kWh
Yearly cost438 kWh × €0.35 = €153.30
This example shows that a single appliance can cost well over €100 per year if it runs regularly. Power and runtime matter more than gut feeling.
Practical example
Household example: what 3,500 kWh per year costs
Even small percentage savings can become meaningful over a full year.
Annual usage3,500 kWh
Electricity price€0.35 per kWh
Yearly consumption cost3,500 × €0.35 = €1,225
10% less usageabout €122 saved per year
20% less usageabout €245 saved per year
Visualization
Where the biggest electricity-cost lever is
The graphic shows why not every appliance has the same impact: the combination of power and runtime matters. A regularly running appliance can matter more than many small devices.
Electricity costs from always-on devices (300 W × 4 h daily)€153 / year
Electricity costs from standby (10 W continuous)€31 / year
Saving from 10% less usage at 3,500 kWh / yearabout €122 / year
If you only optimize one thing, check always-on devices first. They run every day and often cost more than many small devices combined.
How it is calculated
How the electricity cost is calculated in the example
The example shows the key logic behind electricity savings: cost is not only about high power, but power multiplied by runtime and electricity price.
Calculate runtime
4 hours per day equals 1,460 hours per year.
Find consumption
0.3 kW × 1,460 hours = 438 kWh per year.
Apply electricity price
438 kWh × €0.35 per kWh.
Read annual cost
That is about €153 per year.
Set priority
Check always-on devices first because small power values add up over many hours.
In this example, an appliance using 300 watts for 4 hours per day costs about €153 per year.
Mathematical background
Electricity cost is calculated as: power in kW × runtime in hours × electricity price per kWh. The important conversion is watts to kilowatts: 1,000 watts = 1 kW.
If-then rules
If-then rules: what should you do next?
If one appliance costs more than €100 per year
check runtime, usage frequency and whether a more efficient appliance makes economic sense.
If your annual usage is clearly above 3,500 kWh
look first for always-on devices, old cooling appliances, dryers, space heaters or electric water heating.
If your usage is normal but the bill is high
review price per kWh, base fee and contract term of your electricity tariff.
If several devices stay in standby permanently
use switchable power strips or disconnect devices completely.
Step by step
How to interpret this topic
1. Calculate first, then optimize
Many households try to save in the wrong places. What matters is not which device looks suspicious, but how much electricity it actually uses. Cost depends on power, runtime and price per kWh. A high-power device used briefly can be less relevant than a small always-on device running every day.
2. Check the biggest consumers first
Typical cost drivers include old refrigerators, freezers, dryers, space heaters, air conditioners, gaming PCs, aquariums, electric water heating and entertainment devices that run for long periods. Calculate these devices individually before focusing on small consumers.
3. Treat standby and permanent operation realistically
Standby looks harmless but adds up over a year. A device drawing just 10 watts continuously uses about 88 kWh per year. At €0.35 per kWh, that is roughly €31 annually for one device. Several always-on devices can quickly become a three-digit yearly cost.
4. Replacing appliances: not always the first step
A new appliance makes the most sense when the old one uses a lot of electricity and runs frequently. Compare not only the purchase price, but also the yearly difference in electricity cost. If a new appliance saves €80 per year and costs €400, the simple payback time is about five years.
5. Review the tariff when usage is normal
If your usage is normal but your bill is still high, the tariff may be the biggest lever. Check price per kWh, base fee, contract term, price guarantee and bonus conditions. A low kWh price only helps when the base fee and contract terms also fit.
6. The best order for saving electricity costs
Start with the biggest consumers, then check always-on devices and standby, and then review your electricity tariff. Smaller optimizations such as chargers, lighting or habits are useful afterwards. This keeps your effort focused on what actually moves the bill.
Checklist
Quick checklist
- Check annual usage from your electricity bill
- Note price per kWh and base fee
- Calculate the largest devices individually
- Find always-on and standby devices
- Compare old appliances with efficient replacements
- Review your tariff at least once a year
Common mistakes
Common mistakes when saving electricity
Focusing only on tiny consumers
Chargers and individual lights are not irrelevant, but the biggest lever is usually long runtime or high power.
Checking usage but not the tariff
A low-usage household can still pay too much if price per kWh, base fee or contract terms are unfavorable.
Replacing appliances too early
A new appliance is worth it only when the yearly savings are high enough compared with the purchase price.
FAQ
Frequently asked questions
How do I calculate electricity cost for one appliance?
Use power in kilowatts × runtime in hours × price per kWh. Example: 300 watts is 0.3 kW. Used for 4 hours per day, that equals 1.2 kWh daily.
How much can a household realistically save on electricity?
Many households can save around 10 to 20% through tariff checks, less standby use and more efficient habits. With €1,225 yearly consumption cost, that is roughly €120 to €245 per year.
Which devices cause high electricity costs?
Devices with high power or long runtime matter most, such as dryers, space heaters, old cooling appliances, air conditioners, gaming PCs, aquariums and always-on devices.
When is a new appliance worth it?
A new appliance is worth it when the yearly electricity savings are large enough compared with the purchase price. Example: if it saves €80 per year and costs €400, the simple payback time is about five years.
Should I replace appliances or switch tariff first?
It depends on the numbers. If individual devices are very expensive, compare replacements. If usage is normal but the bill remains high, the tariff may matter more.