Judging the power use of mini appliances correctly.

Wattage vs. kWh per year: what means what?

The wattage (W) describes the power draw of an appliance in operation. A mini dishwasher with 1,200 watts draws exactly that amount from the socket at the moment it is actively running. This figure says nothing, however, about how long the appliance works at that power level.

A kilowatt-hour (kWh) is the unit of measurement for energy actually used. 1 kWh corresponds to the amount of energy a 1,000 watt appliance uses in an hour of operation. So if a mini dishwasher nominally draws 1,200 watts but the heating works at full power for only 18 minutes, the result is a much lower value per wash cycle, typically between 0.3 and 0.8 kWh.

For judging electricity costs the kWh value is always decisive. The wattage only provides a peak value, which is important for sizing the power supply.

Energy efficiency class: old A+++ scale vs. new A to G scale

Until 2021 most consumers knew the system with the plus signs: A+, A++ and A+++. Almost all modern mini appliances reached A++, many even A+++. That made the scale useless.

Since March 2021 the new scale from A to G has applied EU-wide. It is considerably stricter: the old class A+++ today usually corresponds to only B or C. Class A deliberately stays empty at first or is reserved for a few top models.

If you see a mini appliance with the new class D or E, it is not automatically a power guzzler. In the new system it sits more in the middle of the field. Always compare the absolute kWh value per year as well.

Hidden power consumers: standby and transformer idle mode

An often underestimated item is the power consumption that arises without the appliance being actively used.

Standby mode: many mini appliances do not switch off completely after use. A single appliance on standby often draws only 0.5 to 3 watts; multiplied by 8,760 hours a year, that quickly gives 4 to 25 kWh per appliance per year.

Transformer idle mode: plug-in power supplies for robot vacuum charging stations or cordless vacuums draw power permanently, even when the actual appliance is fully charged. Typically 0.3 to 1.5 watts per power supply at idle.

Practical tip: an energy cost meter between the socket and the consumer shows within one to two days which appliances draw the most in the background. Such meters cost €10 to €25.

Real consumption values of typical mini appliances

Mini dishwasher: 0.3 to 0.8 kWh per wash cycle

Countertop dishwashers are between 0.3 and 0.8 kWh per wash cycle. With daily use that gives between 110 and 290 kWh a year. Appliances such as the MEDION MD37763 with 0.314 kWh per standard programme mark the lower end. More in the comparison of mini dishwashers.

Robot vacuum: 5 to 10 kWh per year

Robot vacuums are among the most inconspicuous power consumers. A typical appliance works 60 to 120 minutes per cleaning run at 20 to 60 watts in operation. With three to five cleaning runs a week, annual consumption adds up to 5 to 10 kWh. Note: the charging station permanently draws 1 to 2 watts in standby mode, which can exceed the actual cleaning consumption.

Mini fridge: 80 to 150 kWh per year

Mini fridges with 40 to 90 litres need between 80 and 150 kWh a year depending on efficiency class. The difference between class D and class F can amount to 30 to 50 kWh a year; at 35 cents per kWh that corresponds to €10 to €18 a year.

Compressor cool box: 0.28 to 0.86 kWh per day

Portable compressor cool boxes use between 0.28 and 0.86 kWh per day depending on outside temperature and desired inside temperature. Top models such as the Mobicool MCF40 with 0.28 kWh per day are especially economical.

Mini tumble dryer: 1.5 to 2.5 kWh per drying cycle

Compact tumble dryers with 3 to 7 kg need between 1.5 and 2.5 kWh per drying cycle. Heat pump dryers are at the lower end. The Bauknecht T Pure with 1.61 kWh per standard programme shows what is possible at medium load. Overview in the comparison of mini tumble dryers.

Portable air conditioner: 0.7 to 1.0 kWh per hour, the secret power guzzler

No other mini appliance in the home draws as much in continuous operation as a portable air conditioner. A 7,000 BTU monoblock (around 2.0 kW cooling output) draws about 0.8 kWh per hour; if the appliance runs eight hours on a hot day, that is around 6.4 kWh or a good €2.20 in a single day. Here the energy efficiency class is worth a double look: an A+++ appliance such as the De'Longhi Pinguino EX105 uses noticeably less than the A entry-level models. Which appliances cool efficiently is in the comparison of portable air conditioners.

By far the most economical cooling is not an air conditioner at all, though: a fan draws only 2 to 50 watts depending on size, and an efficient DC tower fan costs under 10 cents a day even at eight hours of continuous running, so around a twentieth of the air conditioner. On moderately hot days it is the clearly cheaper choice; the quietest models for the bedroom are in the comparison of quiet fans.

Electricity price calculation: what does it really cost?

In May 2026 the average electricity price in Germany is about 35 cents per kWh. What does that mean in concrete terms?

• Mini dishwasher with daily use (0.5 kWh): 365 × 0.5 × 0.35 = about €64 a year
• Economy model with 0.314 kWh: 365 × 0.314 × 0.35 = about €40 a year, a saving of €24
• Robot vacuum (8 kWh/year): €2.80 a year, negligible
• Mini fridge class E (130 kWh/year): €45.50 a year
• Mini fridge class C (90 kWh/year): €31.50 a year
• Heat pump mini dryer (200 kWh/year): €70 a year
• Standby consumption of 5 appliances at 2 watts each: 87.6 kWh × 0.35 = about €31 a year, for nothing

How a power station can help save electricity

Since the beginning of 2025 all electricity suppliers have been obliged to offer dynamic tariffs. These follow the exchange electricity price and can vary strongly hour by hour. Anyone with a power station can charge it in cheap time windows and run mini appliances from the power station in expensive hours. With a price range of 15 to 45 cents per kWh, savings of 20 to 30 cents per discharged kilowatt-hour result, minus 10 to 15 per cent charging/discharging losses.

Balcony solar systems (Balkonkraftwerke) have been widespread since 2024. A power station as an intermediate store captures the surplus solar power. With 200 kWh of self-consumed solar power a year, savings of €70 result compared with drawing from the grid. An overview of current models is in the power station comparison.

Verdict: from data sheet to real electricity bill

The power consumption of a mini appliance can only be judged seriously if you keep wattage and kWh cleanly apart, place the new energy efficiency class correctly and take into account the often invisible standby consumption. The biggest problem is usually not the nominally strongest consumer but the sum of many small, permanently running appliances. With targeted appliance selection and a switchable power strip, €50 to €150 a year can be saved.

Frequently asked questions

What is the difference between watts and kilowatt-hours?

Watts (W) is the instantaneous power draw, the kilowatt-hour (kWh) the energy actually used over time. For electricity costs, the kWh always counts: a 1,000 watt appliance uses exactly 1 kWh in an hour of operation.

How much does standby consumption cost per year?

A single appliance often draws 0.5 to 3 watts on standby, which over a year (8,760 hours) is 4 to 25 kWh per appliance. Several appliances together quickly reach €20 to €30 a year; a switchable power strip saves that.

Are mini appliances automatically economical?

No. Small does not mean economical: a portable air conditioner or a fan heater draws a lot of power despite its compact design. What matters are the real kWh value and the energy efficiency class, not the size of the appliance.