Welder duty cycle calculator
Enter the rated output and duty cycle off the nameplate and the amps you run. See the minutes welding and cooling in every 10, and the most amps you can hold at the duty cycle you want.
Updated November 2026
Quick answer
Duty cycle is how many minutes out of 10 a welder can run at a given output before it needs to cool. 200 A at 30% means 3 minutes welding and 7 cooling at 200 A. Turn it down and it goes up: by the square law that machine runs about 53.3% at 150 A, and about 110 A at 100%.
How the duty cycle math works
- A 200 A, 30% welder at 150 A: 30 × (200 ÷ 150)² = 53.3%.
- Minutes: 5.3 welding and 4.7 cooling in every 10.
- Most amps at 100%: 200 × √(30 ÷ 100) = 110 A.
Jasic publishes the same formula with a 200 A, 60% machine: about 155 A at 100%, and 38.4% at 250 A. The calculator gets 155 A and 38.4%. Jasic also warns it is only approximate, more so on inverters. The duty cycle chart in the manual wins.
Not sure what amps you'll run? The welding settings chart has starting amps by process and metal thickness.
Duty cycle by amps: a 200 A, 30% welder
† The formula came out over 100%, so the row shows 100%.
Most amps by duty cycle: a 200 A, 30% welder
† Above the 200 A rated output. It only counts if the machine goes that high.
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Questions welders keep asking about duty cycle
What does 30% duty cycle mean on a welder?
30% of 10 minutes: 3 minutes welding and 7 minutes cooling, at the amps the duty cycle is rated at. On a 200 A, 30% welder that is at 200 A. Below that you get more time: about 53.3% at 150 A, or 5.3 minutes in every 10.
How many amps can I run at 100% duty cycle?
Take the rated amps times the square root of the rated duty cycle over 100. A 200 A, 30% welder works out to about 110 A nonstop. Some plates list a 100% rating too; when yours does, use it.
What happens if I go over the duty cycle?
On most machines a thermal overload shuts the output off until the machine cools, then lets you weld again. Running it into the overload all day is hard on the machine. The duty cycle chart in the manual is what to go by.
Is a 60% duty cycle better than 30%?
Only when you compare at the same amps. A 200 A machine rated at 60% holds about 155 A nonstop. One rated at 30% holds about 110 A. Compare duty cycles at the amps you actually weld at.
How accurate is the duty cycle formula?
It's an estimate. Jasic, who publish the formula, say so, and more so for inverters. Our math matches their worked examples: a 200 A, 60% machine comes out 38.4% at 250 A and about 155 A at 100%. Where the manual has a duty cycle chart, go by the chart.
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