Generator For Welding Machine | What Size Generator For Welding?


Welding is a vigorous metal joining technique that necessitates a high voltage and current supply. As a result, many welding projects must be completed indoors, in a workshop or garage with a steady electric power source. It enables the welder to complete the work without fear of running out of power or underperforming the weld due to a disruption in the power supply. We will discuss Generator for Welding Machine thoroughly in this article.

However, it creates a difficulty if the welding must be done at a specific location or outside. Finding a dependable electric wall outlet can be difficult in this area. Furthermore, you must choose one that meets the specifications of your welding setup. As a result, you cannot rely on a welding machine’s portability. Unless you’re traveling with a generator to do some welding.

There are numerous electrical generators on the market that are suitable for welding jobs due to their high voltage output and reasonable fuel efficiency. However, if you want the finest outcomes, you must select the correct generator for your welding setup. Failure to do so may result in damage to several crucial components of your welding setup. To be safe, you should consider the generator’s size, output ports, output capacity, compatible fuel, and other key features.

Suitable Generator Size For a Welder

There are numerous reasons why a welder might require access to a portable generator in order to perform remote welding work. However, selecting the correct one for the welding setup is critical. If the generator power rating is too low, it might lead to flaws in the expensive welding setup, as well as irreversibly damaging some of the electrical components. A too-powerful generator, on the other hand, would be difficult to transport and would have a very high running cost, sometimes exceeding that of the welder itself.

To address these issues, you must select the appropriate size generator for the assignment. The size aspect here relates to the generator’s output capacity. To determine the appropriate size of generator for your task, examine parameters such as amperage needs, wattage rating, generator fuel economy, and so on.

The issue arises when you attempt to compare your welder and its power requirements to what the generator has to give. Because different manufacturers use different standards to indicate specs, the rated output levels can differ from one product to the next. As a result, it is best not to consider the amperage output rating while shopping for a welding generator.

How to Figure Out What Size Generator For Your Welder

This question usually takes one of the following forms:

  • What size generator do I need for a 180-amp welder?
  • Will a 7,000-watt generator run a welder?
  • How big of a welder can you run with a generator of X size?

All of these are the same questions. You’re simply asking from different perspectives.

This Is How You Do It

Generators, like welders, come in a variety of sizes. There are numerous features and settings to choose from.
You’ll also need to specify whether you want 120-volt output, 240-volt output, or both.

The most difficult thing to remember is that generators are rated in total WATTS of power output, whereas welders are rated in output AMPERAGE.

That implies you must determine how many watts a welder requires to produce its rated amps.

Welding Wattage Requirement

There is a simple formula that allows you to easily link voltage, amperage, and watts. Watts = Volts x Amps, as we all know. So, simply multiply the voltage by the amperage rating to get the wattage rating. But first, let’s try to grasp what each of these components implies because it will help you perform the computation more exactly.


Technically, voltage is the difference in potential energy between two locations in an electrical circuit. As a result, the voltage level essentially represents the potential energy existing at each point in the circuit.
Consider it the potential energy present in the water when it is stored at a high point.


An ampere is a measurement of the flow of electrical current in a circuit. As a result, a higher amperage value indicates faster current travel, while a lower rating indicates slower current travel. The amount of electrical current flowing through the system of the maximum amount of currency accepted by the circuit within its safety standards is simply given by an amperage rating.


Wattage, in contrast to other metrics, simply quantifies thermal energy in an electrical system. As a result, when it comes to welding jobs, this is the most crucial factor. You can easily check if a generator is compatible with the configuration by performing the calculation based on the wattage needed by the welder.

How To Calculate Welding Input Requirement?

Now that you understand the main criteria that influence the generator’s compatibility with the welder, let’s look at how to compute the ratings and compare them to see if they are compatible.

Calculating The Welding Power Requirement

First and foremost, you must determine the power and current levels required by your welder to function.
The operator’s manual, which comes with all conventional welding machines, is the ideal place to start.
The voltage and amperage rating of the welder are both listed here. The voltage rating normally has a tolerance of a specific percentage, so keep that in mind when calculating the wattage.

For example, if the voltage rating is 220 volts with a tolerance of 15%, you must factor in 253 volts in the computation. The extra tolerance ensures that the generator you select can manage the welder’s peak power needs.

Following that, you’ll need an Amperage rating to enter into the calculation. For 110 volts, the maximum input current is roughly 46.3 amps. As a result, the approximate power requirement for a 110 Volt welder is 5856 Watts. However, keep in mind that this is only a preliminary rating and that a safety margin of roughly 30% is required.

So, adding 30% to 5856 Watts equals 7612 Watts. However, it is always preferable to round up the estimate to a higher point in order to increase the safety factor. As a result, a generator with an output of roughly 6000 Watts is required for a 110 Volt welder. And the additional 30% required for starting the machine and increasing power spikes should be roughly 2000 Watts higher. As a result, the generator’s highest wattage capacity should be around 8000 Watts.

If you perform the same calculations for a 220 Volt welder, you will discover that the best option for a generator is one with an 8500 Watt wattage rating and an 11000 Watt peak wattage capacity. Even if the information isn’t in the operator’s manual, the power, and current input requirements are clearly written on the welder itself.

Power Supply Differences Between Inverters & Transformers

One critical decision is whether your welding machine is powered by a transformer or an inverter. This is significant because there is a trait known as “dirty power” in welder generators.

“Dirty Power” refers to tiny and frequent changes in engine power as it operates.

These power fluctuations are referred to as “harmonic distortion” and are quantified in terms of Total Harmonic Distortion, or THD. It is expressed as a percentage, such as “5% THD.”

Transformer-powered welders are tolerant of unclean generator power. A transformer-powered welder can be powered by almost any modern generator.

The issue is with machinery powered by inverters. They have issues with dirty power because their control circuits are easily harmed by harmonic distortions in the power supply. They are also known as IGBT and MOSFET welders.

Without getting too scientific, capacitors are used in these systems to filter out distortion and smooth the power supply. Another advantage of using inverter power is that the welder itself can be lighter.

Many current generators are equipped with inverter filters, making them suitable for use with inverter-powered welders.

THD isn’t an issue with a transformer-powered welder, but if you want to run a computer, anything digital, or an IGBT or MOSFET welder, your THD must be less than 6%.

Other Factors Affecting Your Choice

High Altitude Issues

There is less oxygen at high altitudes. Engines that run on gasoline, diesel, or propane produce less power. At high elevations, your welding generator will produce less power than it would at sea level. Generator manufacturers recommend allowing for a 3.5 percent power loss for every 1,000 feet of elevation.

Depending on the height, it could be scarcely detectable or much less powerful. High-altitude kits are available from generator manufacturers.

Extra Tools and Equipment

If you need to run other equipment such as saws, grinders, drills, and so on, you need to add at least another 2,000 watts to the capacity because many grinders and reciprocating saws consume up to 1,800 watts.

Consider fans, heaters, and lights as well. It may be less expensive to purchase a smaller generator for these items rather than a larger generator to power both your welder and extra tools.

How Long Is the Run Time?

This is the amount of time a generator can run at maximum capacity with a full tank of fuel. Some can run for up to 8-10 hours, while others, especially large generators, may only last a couple of hours between refills if they’re working hard.


Generators are loud, although not as loud as certain tools and automobiles. There are also exhaust emissions to consider, as well as the risk of carbon monoxide poisoning. You can’t place a generator inside safely, and all of them have warning labels instructing you not to.

You must ensure that it is well-ventilated, safe from crashes or dropped goods, that cords can reach your work area safely, and that noise will not be a problem where it is sitting.

To determine how loud it is, look at its dB rating. Anything above 90 dB is harmful to one’s hearing.
Drag racers, artillery, jet aircraft, and hunting rifles with decibel ratings of 120 or above are practically deafening.


This chart summarizes some National Electrical Manufacturers Association (NEMA) extension cord length guidelines. Connect gadgets directly to the generator wherever practical.

Your coffee machine can brew until you take a break, at which point you can pour a cup after walking over and turning off the generator.

Generators with an operating power of 4Kw or more might easily weigh more than 200 pounds. Wheel kits, wheelbarrow-style handles, and lifting bales for hooks are all devices that make positioning such a large piece of equipment much easier.

Which Welding Generators Are Suitable For Your Job?

You should now understand how to pick the proper generator based on the specs of your welder as well as the output capacity of the generator itself. However, rather than performing intricate calculations, you may just refer to the comparison table that we have produced for you.

Here, we shall directly compare the approximate generator wattage with the amperage rating of the welder.
So, before purchasing the generator, you can refer to the wattage rating supplied below.

Approximate Welder AmperageMinimum Required generator WattageRecommended Generator Wattage
Less than 100 Amps3000 WattsUp to 4500 Watts
120 to 160 Amps4500 WattsUp to 6500 Watts
180 to 200 Amps6500 WattsUp to 8000 Watts
210 to 250 Amps10000 WattsUp to 13000 Watts

You’ve come to the right place if you’re seeking the best generator for outdoor welding projects. This guide has addressed the fundamentals of a generator, its compatibility with welders, and procedures to help you discover the best option for your welder. As a result, after reading our instructions, you will be able to simply select the best size generator for your welder.

We also have a reference chart available if you need a quick reference for standard welder parameters.
However, ensure that the generator you choose has at least 30 to 50% more power output rating than what the welder requires. While it may raise your operating costs, it is unquestionably a wise investment for long-term use and future updates.

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