Generator Wattage for a Welder: Read the Two Figures

A generator listing states two wattage figures

A generator listing states a running watts figure and a starting watts figure. Running watts, sometimes called continuous watts, is the power the generator can supply steadily. Starting watts, sometimes called surge or peak watts, is the higher burst it can supply for a short moment when a load first turns on. The U.S. Energy Information Administration explains watts as the unit of power; the figure on the listing is the number to compare against a welder's input requirement. See running watts versus starting watts for more on the two figures.

A welder draws power from the generator according to its input requirement, which the maker states on the nameplate. The nameplate lists the input voltage, such as 120V or 240V, and the input amperage. Those two figures together describe how much power the welder asks for. The generator listing gives output in watts, so the comparison starts with reading both figures in the same unit.

Welder input requirements and the nameplate

The nameplate on a welder is the first place to read. It states the input voltage and the input current. The manual may state the input in watts or kilovolt-amperes (kVA) directly. When the manual gives volts and amps, watts are the product of volts and amps for a DC load; for an AC load with a power factor, the maker's stated input figure is the one to compare.

This article cannot state the watts for your welder because the input depends on the model and the amperage setting you choose. Read the welder's nameplate and the maker's page. Then read the generator listing's running and starting watts.

Duty cycle and what it means for generator shopping

Duty cycle is a rating term on a welder: it is the percentage of a 10-minute period the welder can run at its rated output before it needs to cool. A 40% duty cycle means 4 minutes of welding in each 10-minute window. The duty cycle affects the average draw over a job, because you pause between welds. The generator's running watts still has to cover the steady draw while you weld, and the starting watts has to cover the moment the arc strikes.

See generator duty cycle for the term explained in general terms.

Surge, starting watts, and the arc strike

A welder draws a brief surge when the arc strikes, and a wire feeder or cooling fan can add a short surge when it starts. The generator's starting watts figure is the figure that pairs with that brief peak. The running watts figure pairs with the steady draw during the weld. A listing may show the starting figure first; read the full title to find both figures.

How to compare a welder with a generator listing

Read the welder nameplate for input volts and amps. Read the generator listing for running watts and starting watts. If the manual states the welder's input in watts, compare that directly with the running watts. If it states volts and amps only, the maker's input figure is the one to use. The comparison is between the welder's input requirement and the generator's output; neither figure promises that a specific weld will run.

When the listing does not state a starting watts figure, treat it as unstated and ask the maker. The same applies to the welder's duty cycle and input: if a figure is missing, the maker's manual or the maker's support page is the next place to read.

Shopping before hurricane season in Florida

The time to compare backup power options is before hurricane season, as the National Weather Service advises in its before-storm checklist. The Florida Division of Emergency Management Plan & Prepare page lists preparation steps, and the generator safety page notes that you should check with your building management or local regulations to understand what backup power solutions are already in place. If you live in a county, visit the county emergency management program for locally significant information. To compare stated figures on different types, see the best inverter generators for Florida and best large portable generators for hurricanes guides.

Why this article gives no wattage table

This article does not tell you which wattage runs a specific welder, because every welder model has a different input requirement and every generator listing states its own figures. The site's guides compare generators on stated details; the running and starting watts in each listing are the figures to read. For generator placement and carbon monoxide guidance, follow the maker's manual and read the CPSC and Florida Division of Emergency Management generator safety pages in the sources. See generator carbon monoxide safety for a pointer.

What to pick for your situation

Questions

What does duty cycle mean on a welder?

Duty cycle is the percentage of a 10-minute period the welder can run at its rated output before it needs to cool. A 40% duty cycle means 4 minutes of welding in each 10-minute window. It affects the average draw, not the peak.

What is starting watts on a generator?

Starting watts is the higher burst a generator can supply for a short moment when a load first turns on. It pairs with a welder's arc strike and any motor start.

Can a portable power station run a welder?

Only if the welder's input requirement fits within the station's stated continuous AC output. Read both figures; many welders need more than a portable station can supply. For apartment-friendly options, see the best power stations for apartments.

Where do I find the welder's input requirement?

On the welder nameplate, which states input voltage and current. The manual may state the input in watts directly.

What if the generator listing does not state starting watts?

Treat it as unstated and ask the maker before you buy. The running watts figure alone is not enough to compare against a welder's peak draw.

Do I need a 240V generator for a welder?

Only if the welder's nameplate states 240V input. Read the input voltage on the nameplate and match it to the generator's stated outlet voltage.