What size generator do I need: expert advice

Today's generator market is overflowing with models ranging from domestic to industrial diesel stations. But the main question remains the same: how to choose a generator that can withstand the actual load and will not turn into a ‘temporary solution’? If you decide to buy a generator for your home, pay attention not only to the price, but also to the power, fuel type and noise level — these details will determine how comfortable you will be during the next power outage.

Why is it important to choose the right power generator?

First of all, the stability of the power supply will depend on this. It is the understanding of where the generator will be used that determines its size and type that you need. For example, if you plan to power only a few light bulbs, a refrigerator and a boiler, a small 3-5 kW petrol generator will suffice. But when it comes to a farm, workshop or production facility where engines, pumps, ventilation or cooling systems are running simultaneously, a completely different level of power is required.

A generator that is too weak will simply ‘choke’ under the load: it will operate at the limit of its capabilities, overheat, consume more fuel and break down faster. On the contrary, one that is too powerful will be an unjustified luxury: you will overpay for both the device itself and fuel costs.

The right choice is a balance between needs and safety margin. Experts advise calculating the power with a small reserve of 20-30% so that the generator does not run at full capacity all the time. And also — take into account the ‘starting currents’: electric motors and compressors consume two to three times more energy at the moment of start-up than during stable operation.

So, before buying a generator, it is worth sitting down and honestly calculating how many electrical appliances you want to connect and how much power each of them consumes. This is the simplest but smartest thing you can do to ensure that the generator serves you for a long time and without surprises.

Step 1. Familiarise yourself with the basic electrical terms

For easier understanding, let's draw an analogy between electricity and water supply.

Volts (V) are the pressure of water in a pipe: the higher it is, the stronger the water (i.e. electricity) pushes forward. In domestic networks, 220 V is considered the norm, and in industrial networks, 380 V.

Amperes (A) are the amount of water flowing through a pipe per second, i.e. the power of the electron flow. The higher the current (amperes), the more energy is consumed.

Watts (W) is the total power of the flow, which shows how much work electricity does.

Watt-hours is the amount of water that flows through a pipe in a certain amount of time, i.e. energy.

This analogy helps to understand why generators should be selected not only by their power in watts, but also by the voltage they output and the load they can withstand.

Step 2. Make a list of devices and determine their power

In order to correctly determine the power of the generator, you first need to know how many watts each electrical appliance consumes. This information can be found on the label on the device, which indicates the main parameters: voltage (V), current (A) and power (W). The power is also indicated in the ‘Technical Specifications’ section. There are special devices that show the actual energy consumption.

For example, a refrigerator consumes 100-300 W, depending on its size and energy efficiency class. An air conditioner consumes 800-2500 W for a small room and 3000-5000 W for a large room. A television consumes between 50 and 250 watts. Power tools also vary: a drill consumes 500-1200 watts, an angle grinder consumes 800-2200 watts, and a circular saw consumes 1200-2000 watts.

But remember, it is important for the generator to take into account the starting current of power tools and refrigerators, which can be two to three times higher than the nominal current.

Why are marked lists convenient? Because you can list devices without complicated tables and show the power range for different models of the same type of device.

Step 3. Calculate the total power

To choose the right generator, you need to know the total power of all the devices that will be operating simultaneously. Therefore, simply add up all the wattage ratings of the devices, plus add a 20% reserve — this is a guarantee that the generator will not operate at its limit and will withstand short-term overloads. We also take into account the starting current. Devices with electric motors (refrigerators, air conditioners, tools) consume a starting current 1.5-3 times greater than the nominal current. 120 and 240 V appliances are added separately if the generator does not support both voltages simultaneously.

Add a 20% reserve and we get 7020 W.

Types of generators and their power

Now let's look at the type of fuel. Petrol generators are well suited for short-term use and are characterised by quick start-up. They have an internal combustion engine, are lightweight and mobile. Typical power ranges from 1 to 7 kW. When planning to buy a petrol generator, you should immediately decide how often you will use it — for short outages, it is a convenient and compact option, but for long-term operation, it is better to consider a diesel model.

Diesel generators are more economical during long-term use and have a more powerful engine. They are better suited for heavy loads. Their typical power is 5-200 kW and above. If you want to buy a diesel generator, choose a model with power reserve — such units are designed for long-term, stable operation and are ideal for homes, farms or manufacturing.

Inverter generators have a petrol or diesel engine with an electronic unit that produces stable, clean voltage. They can be connected to sensitive electronics and are lighter and more compact than classic petrol or diesel models, although they are slightly more expensive. Typical power output is 1-10 kW. To ensure stable and clean electricity for sensitive equipment, it is worth buying an inverter generator that combines compactness, quiet operation and stable voltage.

If you have already decided on the type and model of generator, you can now start looking for a store. Visit the VADA online store, where you will find a large selection of generators for various needs. We guarantee the quality of our products, fair prices and fast delivery throughout Ukraine. And if you still have doubts about the type of generator, our consultants will help you decide and select the model that best suits your needs.

08/10/2025