How much electricity does welding use? A typical 240-volt shop welder draws roughly 3 to 7 kW while the arc is running, which costs about 55 cents to $1.30 per arc hour at the US average residential rate of about 18 cents per kWh. Small 120-volt welders draw less, and large three-phase machines draw more. Because most welders arc for only a fraction of the day, a home shop usually adds just a few dollars a month to the bill.
Quick Answer
Electricity cost = input power (kW) × arc-on hours × your rate per kWh. Use the machine’s input rating from its data plate, not the welding output amps. At the August 2026 US average prices reported by the EIA (about 18.2¢ residential, 14.5¢ commercial and 9.6¢ industrial per kWh), one hour of arcing at 5 kW costs roughly 91 cents, 72 cents or 48 cents.
Key Takeaways
- kW is how much power the welder draws at a moment; kWh is the energy you are billed for over time.
- Calculate from input voltage, input amps and power factor, not from output weld amps.
- Inverter welders are generally more efficient than older transformer welders. Manufacturer examples put inverters at roughly 85 to 87 percent and transformers at roughly 67 to 80 percent.
- Arc-on time is usually a small share of a work day, so billing hours are far lower than clock hours.
- Never size breakers or wiring from an energy estimate. Use the welder manual, the National Electrical Code and a qualified electrician.
How Welding Machines Use Electricity
A welding power source converts utility power into the low-voltage, high-current output that melts metal. Some energy is lost as heat in the machine, and the cooling fan, controls, wire feeder and any water cooler also draw power.
- Kilowatt (kW): the power drawn at any moment.
- Kilowatt-hour (kWh): the energy billed. A 5 kW welder arcing for 30 minutes uses 2.5 kWh.
- Power factor (PF): the ratio of real power to apparent power (volts × amps). Check the machine’s data plate or manual for the value.
The U.S. Energy Information Administration explains that household bills are based on kilowatt-hours used. Commercial customers may also pay demand charges based on peak kW.
Do not multiply output amps by wall voltage: Welding at 180 output amps and 22 arc volts delivers about 3.96 kW at the arc (180 × 22). With an inverter at about 85 percent efficiency, the machine draws roughly 4.7 kW from the wall (3.96 ÷ 0.85). A breaker size such as 50 A is a circuit limit, not what the welder actually draws.
Typical Welder Power Draw by Machine Type
Real draw depends on the model and how hard you run it, so treat these as ballpark figures and confirm with your data plate.
| Machine type | Typical supply | Approximate draw while welding | Approx. cost per arc hour (18.2¢/kWh) |
|---|---|---|---|
| Small 120 V MIG or stick | 120 V, 15 to 20 A circuit | Up to about 1.5 to 2.4 kW | About 27 to 44 cents |
| 240 V shop inverter (MIG, TIG, stick) | 240 V, 30 to 50 A circuit | About 3 to 7 kW | About 55 cents to $1.27 |
| Older 240 V transformer welder | 240 V, 50 A circuit | About 4 to 9 kW | About 73 cents to $1.63 |
| Industrial three-phase | Three-phase 230 or 460 V | About 10 to 20 kW or more | About $1.82 to $3.63+ |
These ranges are estimates based on typical nameplate ratings, not measured figures for every model.
Single-Phase Formula
kW = volts × input amps × power factor ÷ 1,000
Example: a 240 V machine drawing 25 input amps at a 0.90 power factor uses 240 × 25 × 0.90 ÷ 1,000 = 5.4 kW.
Three-Phase Formula
kW = 1.732 × volts × input amps × power factor ÷ 1,000
Example: a 480 V three-phase machine drawing 20 amps per phase at a 0.92 power factor uses 1.732 × 480 × 20 × 0.92 ÷ 1,000 = about 15.3 kW. For more on the maths, see the Fluke power factor guide.
How Duty Cycle Affects Energy Use
Duty cycle is the share of a 10-minute period a welder can run at a given output before it needs to cool. A machine rated 60 percent at 200 A can weld for 6 minutes, then needs 4 minutes to cool. It limits how long you can weld, not how efficient the machine is. Miller explains that duty cycle rises as output current drops.
Example hour with a 6 kW machine arcing 36 minutes (60 percent of the hour):
- Arc energy: 6 kW × 0.6 h = 3.6 kWh
- Standby energy: a small inverter may draw a few dozen watts when idle, so well under 0.05 kWh
- Cost at 18.2¢/kWh: about 66 cents
Warning: Do not defeat thermal protection or block cooling vents to get around duty cycle limits. Overheating can damage the machine and create a fire or shock hazard.
How to Calculate Your Welding Electricity Cost
- Find the input rating. Read the data plate for input voltage, input amps and, if listed, power factor.
- Calculate input kW. Use the single-phase or three-phase formula above.
- Track arc-on time. Estimate the minutes you actually weld, not the hours you are in the shop.
- Add extras. Include standby draw, a water cooler, fume extraction and other equipment.
- Multiply by your rate. Use the price per kWh on your own bill.
The EIA Electricity Monthly Update reported US average retail prices in August 2026 of 18.16¢ per kWh for residential, 14.47¢ for commercial and 9.64¢ for industrial customers. Your local rate can be quite different.
| Scenario | Assumptions | Energy | Estimated monthly cost |
|---|---|---|---|
| Home hobbyist | 5 kW machine, 12 minutes of arc per session, 12 sessions | 12 kWh | About $2.18 at 18.16¢/kWh |
| Small fabrication shop | 6 kW machine, 40 arc hours plus about 5 kWh standby | About 245 kWh | About $35 at 14.47¢/kWh |
| Industrial production | 15 kW machine, 4 arc hours a day, 22 days | 1,320 kWh | About $127 at 9.64¢/kWh |
These examples exclude demand charges, fixed fees and taxes, which can raise a commercial bill.
Pro Tip: Arc-on time is often only a modest share of a working day because you also fit, clamp, grind and inspect. Costing every shop hour as arc time will badly overstate your bill.
What Changes Welding Power Consumption
- Output current and arc voltage: higher settings draw more power.
- Machine design: inverters waste less energy as heat. Miller cites about 85 percent average efficiency for inverters versus about 80 percent for three-phase transformers, and Lincoln Electric gives an example of 87 percent versus 67 percent. These are manufacturer figures, so your savings will vary.
- Cable length and condition: undersized or damaged leads waste energy as heat.
- Process and technique: faster travel and good fit-up mean less arc time per part.
- Extra equipment: water coolers, fume extractors and air compressors can add real load.
How to Cut Welding Electricity Costs
- Consider an inverter when replacing an old transformer machine, especially if it runs many hours a week.
- Improve fit-up so you need fewer passes and less rework.
- Use correctly sized, clean, tight leads. See our welding leads cost guide.
- Switch off the welder and extraction when you leave the booth for a long time.
- Check your rate plan and avoid peak-demand periods if you are billed for them.
Grid Power vs Engine-Driven Welders
Grid electricity is almost always the cheaper way to power a welder because one kWh costs only cents. Field work often needs an engine-driven welder or a generator, where fuel, maintenance and the machine itself cost more than the electricity. If you plan to run a welder from a portable generator, follow the welder manufacturer’s generator guidance, because arc starts can surge well above the running load. For equipment prices, see our guide to what welding equipment costs.
Electrical Safety and Circuit Requirements
An energy estimate is not a wiring plan. Circuit breakers, conductors and receptacles for arc welders are covered by the National Electrical Code (Article 630) and local rules, so ask a qualified electrician to size them. Welding equipment safety is also covered by OSHA 1910.254.
- Use the circuit and plug the manufacturer specifies.
- Disconnect power before opening the machine.
- Do not use extension cords that are not rated for the welder.
Carbon Footprint
The emissions from welding electricity depend on how your local grid generates power. The EPA Power Profiler shows the fuel mix for your area.
Frequently Asked Questions
How much electricity does a welder use per hour?
A typical 240-volt shop welder draws roughly 3 to 7 kW while welding, so about 3 to 7 kWh per hour of continuous arc. Small 120-volt units draw less and large industrial machines draw more. Check the input rating on the data plate.
How much does it cost to run a welder for an hour?
At the August 2026 US average residential rate of about 18.2 cents per kWh, a 5 kW welder costs roughly 91 cents per hour of arc time. Your cost depends on your local rate, your machine and how much of the hour you are actually welding.
Does a welder use electricity when idle?
Yes. Fans, controls and displays draw some power whenever the machine is switched on. Idle draw is usually small on modern inverters, but it varies by model, so switch the machine off when you are away from it for long periods.
Are inverter welders cheaper to run than transformer welders?
Often, yes. Manufacturer examples put inverters at roughly 85 to 87 percent efficient and older transformer machines at roughly 67 to 80 percent. The real saving depends on how many hours you weld and your electricity rate, so a hobby welder may never recover the extra purchase price through power savings alone.
Can a 120 V household outlet run a welder?
Small welders designed for 120 V can run on a standard household circuit, but many need a dedicated 15 or 20 amp circuit to avoid tripping the breaker. Check the manual for the required circuit and do not use light-duty extension cords.
Does duty cycle change my electricity bill?
Not directly. Duty cycle limits how long you can weld at a given output before the machine must cool. Your bill depends on the energy used while the arc is running and the machine is on.
Can I run a welder from a generator?
Often yes, but the generator must be large enough for the welder’s input draw and arc-start surge. Follow the welder manufacturer’s generator recommendations and do not guess the size.
Conclusion
Welding uses less electricity than most people expect once you count only the time the arc is actually running. Find your machine’s input rating, estimate real arc-on hours and multiply by your local rate. For a home shop that is usually a few dollars a month; a production shop can reach the low hundreds.
To compare running costs with other expenses, see our guides to welder power consumption, welding cost per hour and MIG welding costs.
