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You are watching: How big of a generator do i need to run a welder

What dimension generator do I should run a welder?

I get asked that a lot.

There are great reasons why it renders sense.

You should repair a door that’s no close sufficient to family members powerA friend’s truck is broken down out on the trailYou want to develop a greenhouse in your garden

But if it’s as well small, you could damage or kill your expensive welder.

Too big, and it may price too lot to run, be hard to move, and also take up too lot room.

How to figure Out What size Generator For her Welder

This inquiry usually takes one of these forms, for example:

What size ggenerator carry out I require for a 180 amp welder?Will a 7,000-watt generator operation a welder?How large of a welder can you run with a generator of X size?

These space actually all the exact same questions. You’re just asking the from different viewpoints.

This Is how You perform It

Generators, choose welders, come in too many of various sizes. There space a many of features and options available. And also you’ll should decide if you want 120-volt output, 240 volts, or both.

The trickiest point to watch out for is that generators are rated in complete WATTS of strength output, yet welders room rated for calculation AMPERAGE.

That method you need to figure out how plenty of watts a welder needs to create its rated amps.

How plenty of Watts Does your Welder Use?

There’s a very simple math equation to move earlier and forth in between volts, amps, and watts:

Volts x Amps = Watts

Volts: The technical an interpretation is “a measure of the distinction in electric potential in between two points.”

Think the volts in the same way you think of water pressure. The the available “push” the gets the electrical energy going.

Amps: Amperes space a method to measure up the circulation of electrical current.

Keeping with our water it is provided analogy, think that amps together the price of flow in the pipes, fast or slow.

Watts: A watt measures heat energy. Together electrons flow through the circuit, friction provides heat, measure up in watts.

So what you require is the voltage the welder uses, multiplied by the input amps the the welder.

Find her Welder’s input Power

Step 1: discover the strength & current levels

First, you need to understand what power and current levels your welder requirements to run. A commonplace to discover this information is in the manual.

Here’s an instance from the manual for the PrimeWeld rod 160.


Checking the specifications, as soon as again, there space numbers right here for “Current Input”. This brand is easier to occupational with 보다 some because it gives both intake voltage and also the input present needed by the welder.

It’s basic to figure out just how much power you need in watt from a generator for her welder. Because that the 140-amp version, multiply:

120 volts intake x 23 amps = 2,760 watts

That’s only the an easy number, however. The characteristic the power devices to use much more power to begin than the takes to save them running.

Generator makers advise including up come 30 percent come the running watts to account for beginning devices.

2,760 watt x .30 = 828 watts

Add this 30 percent security margin to the straightforward running number of 2,760 watts:

2,760 + 828 = 3,588

This amounts to 3,600 watts. This welder will need a generator rated at 2,800 operation watts, with a optimal rating of 3,600 watts.

Take away notes:

DON’T FORGET to add specified tolerance, favor our example was plus or minus 15 percent. ALWAYS add THE yongin IN.REMEMBER come ADD 30 percent to your full wattage come cover the beginning surge. The exemption to this rule is if you’re making use of a value well-known as “I1max“. Watch the next section for much more information.Input Values have the right to Have other Names too

Sometimes over there are numerous different types of electric ratings. You might not have actually a rating top top the brand that’s specifically referred to as “input voltage” or “input current,” yet there are other names because that them.

No must be confused, however. Inspect for values v these names instead:

Input VoltageMax PowerMax VoltageV max or VmaxU max or UmaxU1maxInput CurrentMax AmperageMax CurrentA maxI maxI1max

Note that selection 5 in both instances has a notation of 1max. This surname specifically suggests main entry power.

I2 or I2max means output power.

The I1max rating is already changed for rise or starting watts. If you calculate v I1max, you already have her maximum beginning watts rating without a require to include 30 percent.

Another unit you periodically see top top a generator because that welders is the Kilovolt Amp or KVA.

For this unit 1,000 volts x 1 Amp = 1 KVA, the same as 1 Kilowatt (Kw).

Remember: Volts x Amps = Watts

Because 1 KVA = 1 Kw, a generator that makes 6 KVA of peak power is also rated at 6 kW.

Power supply Differences in between Inverters & Transformers

One important choice is whether her welding an equipment is it is provided by a transformer or is one inverter welder. This matters because with generators for welders, over there is a quality called “dirty power.”

“Dirty Power” method small and repeated fluctuations in the strength level as the engine runs.

These fluctuations in strength are called “harmonic distortion” and measured in devices of full Harmonic Distortion, or THD. It’s presented as a percentage, because that instance, “5 percent THD.”

Transformer-powered welders are fairly forgiving that dirty power from a generator. Virtually any modern-day generator deserve to run a transformer-powered welder.

The trouble is with inverter-powered machines. Generally called IGBT and MOSFET welders, lock have problems with dirty power since their regulate circuits are quickly damaged by harmonic distortions in the strength supply.

Without gaining too technical, this designs use capacitors to filter the end distortion, smoothing the power supply. One more benefit that inverter power is the welder itself have the right to be lighter.

A lot of contemporary generators are designed with inverter filters, make them for sure for inverter-powered welders.

If you have a transformer-powered welder, THD isn’t a problem, but if you desire to operation a computer, noþeles digital, or an IGBT or MOSFET welder, you have to be listed below 6 percent THD.

Other determinants Affecting your Choice

High Altitude Issues

At high altitudes, there’s less oxygen. Gasoline, diesel, and propane engines run less efficiently, making much less power. Her welding generator will make much less wattage at high altitudes 보다 it would certainly at sea level. Generator equipments advise plan on a 3.5 percent strength loss for every 1,000 feet the elevation.

Depending on the elevation, it could be right noticeable, or it could be a lot less power. Generator makers offer high-altitude kit to help.

Extra Tools and Equipment

If you need to run extra tools like saws, grinders, drills and the like, you require to include at least one more 2,000 watts to the capacity because many grinders and reciprocating saws take it as much as 1,800 watts to operate.

Also, take into consideration fans, heaters, and lighting. It might actually it is in cheaper come buy a smaller generator for these accessories than one huge one to operation both your welder and extra tools.

Here’s a partial perform of usual devices and also their power demands:

ApplianceRunning WattsStarting Watts
Coffee Maker17500
625W Microwave625800
Single 60W equivalent CFL bulb150
Room waiting Conditioner: 10,000 BTU15002200
Small Appliance2001700
8in. Bench Grinder14002500
Pressure Washer: 1 HP12003600
7-1/4in. One Saw14002300
Electric Chain Saw: 14in. Bar, 2 HP11000
10in. Table Saw18004500
Drill: 3/8in., 4 Amps440600
Drill: 1/2in., 5.4 Amps600900
Portable Heater (Kerosene, Diesel Fuel): 90,000 BTU500725
Battery Charger: 60 Amp through 250 Amp Boost1500/57500
LCD computer system Monitor250
Inkjet Printer150
Cell call Charger100

How long Is the run Time?

This is exactly how long a generator deserve to run at full demand, v a complete tank that fuel. Some can run as lengthy as 8-10 hours, if some huge generators could only last a couple of hours between refills if they’re functioning hard.


Generators space loud, although generally not together loud as part tools and also vehicles are. Over there are also exhaust fumes come consider, with the danger of carbon monoxide. Friend can’t put a generator inside safely, and also they all have actually labels informing you no to carry out this.

You must make sure it’s ventilated well, protected from collisions or reduce items, cords deserve to reach your work-related area safely, and also noise won’t be a problem where the sitting.

Check the dB rating come see exactly how loud that is. Anything over 90 dB is damaging come hearing. 120-decibel ratings and over are indistinguishable to precise deafening sounds prefer drag racers, artillery, jet aircraft, and also hunting rifles.


This chart provides some National electrical Manufacturers (NEMA) recommendations on expansion cord length. Anytime possible, plug tools directly right into the generator.

Your coffee maker can brew until you take it a break, then you can pour a cup as soon as you to walk over and also shut off the generator.

Total Wattage10 gauge cord12 gauge cord14 gauge cord16 gauge cord
2,400250 feet150 feet100 feet75 feet
4,800125 feet75 feet50 feet25 feet
7,20060 feet35 feet25 feet10 feet
9,60030 feet15 feet10 feet0
12,00015 feet000

Generators through 4Kw or more running wattage can easily weigh over two hundred pounds. Wheel kits, wheelbarrow-style handles, and also lifting bales for hooks are all items that make points a lot simpler when placing such a heavy piece of equipment.

Related: What size Wire because that Welder expansion Cords?

Generator Sizing Chart because that Welders

Here’s a rapid reference table I placed together to provide you one idea that what dimension generator you should be aiming for, depending on your welder’s existing level.

Welder existing LevelMinimum Generator SizingRecommended Generator Size
Up come 160A7kva 0r 7000 watts8000+ watts
180–200A8kva or 8000 watts10,000+ watts
210-250A13kva or 13,000 watts15,000+ wats

Best Generators for Welders

I’m going with substantial portable generators here.

You don’t desire your generator working also hard, running level out. It’s much easier on your new power plant if it’s no breathing tough to get the job done.

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Cleaner and more consistent power, much less wear, and longer life are the rewards that a small extra investment.