Welder Duty Cycle Explained
Thirty percent at 150 amps means three minutes of welding in every ten. Here is how to read the figure, convert it, and judge whether it will ever actually stop you.
What does duty cycle mean on a welder?
Duty cycle is the proportion of a ten-minute period a machine can weld at a stated output before it has to stop and cool. A rating of 30% at 150 A means three minutes of arc time at 150 amps, then seven minutes off. The formula is arc minutes = duty cycle × 10. Duty cycle is a curve, not a single number: back the output off and the rating rises, which is why the Lotos LTP8000 publishes 60% at 80 A and 100% at 50 A. For most home welding it is the least limiting specification on the sheet, because a home shop spends far more time measuring, clamping and grinding than welding.
Duty cycle appears on nearly every page of this site as a reason to prefer one machine over another, and it is also the specification most often used to sell people more machine than they need. Both of those can be true, and the difference is arithmetic.
The formula, and reading a rating
The industry convention is a ten-minute window. So:
Arc minutes available = duty cycle percentage × 10 ÷ 100.
20% is two minutes on, eight off. 30% is three on, seven off. 60% is six on, four off. 100% means continuous — no cooling pause at any point.
Two things make the figure less simple than it looks. First, it is quoted at a stated output, and that output is part of the rating: 30% at 150 A and 30% at 90 A are not the same claim. Second, it is measured under stated conditions — supply voltage and ambient temperature among them — so a machine in a hot garage in August will not match its sheet.
Duty cycle by rating, in minutes
| Rating | Arc time per 10 min | Cooling time | What it feels like in practice |
|---|---|---|---|
| 20% | 2 minutes | 8 minutes | Fine for tacks and short beads; stops you on a long run |
| 30% | 3 minutes | 7 minutes | A real working figure for home fabrication |
| 35% | 3.5 minutes | 6.5 minutes | Comfortable for stick runs on 1/8 in rod |
| 40% | 4 minutes | 6 minutes | Beyond anything hobby TIG asks for |
| 60% | 6 minutes | 4 minutes | You will hit the air supply or your own stamina first |
| 100% | Continuous | None | Professional. Long cuts and production work |
Why it matters less at home than you think
Write down what you actually did last time you welded something. Measure, cut, grind, deburr, clamp, check square, tack, check square again, re-clamp, weld two inches, chip, brush, inspect, reposition.
The welding in that list is perhaps thirty seconds in ten minutes — a 5% duty cycle. A machine rated 20% has four times the arc time a typical home fabrication job demands, which is why best welders for hobbyists argues that duty cycle stops being the argument at this level.
The honest exceptions, where duty cycle does bite:
Long continuous beads. A trailer deck, a long fence rail, a structural fillet that has to be run in one pass. These are genuinely continuous and a 20% machine will stop you.
Learning. Beginners run hot and dwell, both of which load a machine harder than the settings suggest. The first ten hours is when you are most likely to find the thermal cutout.
Plasma cutting. A cut is continuous by nature, and stopping mid-cut leaves a defect you have to grind out. This is the one process where the rating is load-bearing in a home shop — the cut thickness chart pairs with it.
Summer in a closed garage. Ratings assume an ambient temperature. A hot garage with no airflow reaches the cutout sooner than the sheet implies, and that is a real effect rather than a machine fault.
What happens when you exceed it
Nothing dramatic. Every modern inverter has a thermal cutout: the machine stops welding, usually lights an indicator, and resumes when the internal temperature drops. It is a protection feature, not damage, and hitting it occasionally is not abuse. What does cause harm is defeating the cooling — blocking the fan intake, standing the machine against a wall, or letting the vents fill with grinding dust. Keep the air path clear and the duty cycle looks after itself.
Reading a duty cycle claim sceptically
Three things to check before you weigh one machine's rating against another's.
At what output? A generous percentage quoted at a modest current is a weaker claim than a lower percentage at maximum. The AHP AlphaTIG 200X publishes 60% at the full 200 A, which is the honest version.
At what supply voltage? Hobart publishes 30% at 150 A and 20% at 90 A for the Handler 210 MVP because those are measured on 230 V and 115 V respectively. Dual-voltage machines have two curves, and one number can only describe one of them — 120V versus 240V welders covers what else changes.
For which process? A multiprocess machine loads differently on stick than on TIG. A single figure covering both is either optimistic for one or conservative for the other.
And one broader point: a machine that publishes nothing has told you something. Several budget machines in this registry publish no duty cycle at all, and where a figure is not published this site leaves the row blank rather than estimating one. If continuous arc time matters to your work, treat that absence as the answer — what size welder do I need is the page that puts it in context with output and thickness.
What we would buy
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1. The clearest published figure
Hobart Handler 210 MVP
30% at 150 A and 20% at 90 A — two points on the curve rather than one, which is what makes a duty cycle rating usable.
Hobart publishes gas MIG and flux-core; 115 V or 230 V via the multi-voltage plug; 25 to 210 A (140 A on 115 V, 210 A on 230 V); a 30% duty cycle at 150 A and 20% at 90 A; 24 gauge to 3/8 inch single-pass capacity; and seven voltage settings on 230 V.
Two published points is unusual and genuinely useful. A single figure tells you one thing about one current; two let you see which way the curve runs on this specific machine, and here it runs in the direction that surprises people — the rating is lower at the lower current.
That is because the two figures are measured on different supplies: the 20% at 90 A figure reflects 115 V operation and the 30% at 150 A figure reflects 230 V. It is a good reminder that a duty cycle is a measurement under stated conditions, not a property of the box.
30% at 150 A is a real working figure rather than a demonstration figure, which is what you want from a machine you intend to run through an afternoon.
Costs: on 115 V you get 140 A, no more than the much cheaper Handler 140EZ, so the value appears only once the 240 V circuit exists; and it is heavy enough to want a cart.
What works
- The multi-voltage plug means you can buy it before you have run a 240 V circuit and get the full 210 A later
- 3/8 in single-pass capacity covers essentially every home fabrication job
- 30% duty cycle at 150 A is a real working duty cycle, not a demonstration figure
What does not
- Heavy enough that you will want a cart, which is another purchase
- On 115 V you get 140 A — no more than the Handler 140EZ, at a much higher price. The value only appears once you have the 240 V outlet
- No spool gun included, so aluminum is a further purchase
2. Best duty cycle for the money
AHP AlphaTIG 200X
60% at 200 A TIG and 35% at 155 A stick, published per process — which is rarer and more useful than a single headline number.
AHP publishes AC/DC TIG and stick; 110 V or 220 V single phase; 10 to 200 A; a 60% duty cycle at 200 A TIG and 35% at 155 A stick; capacity 24 gauge to 3/8 inch mild steel and aluminum to 1/4 inch; AC balance 30 to 70%; and 50 lb.
Publishing the rating per process is the detail worth noticing. Stick and TIG load a machine differently, so one number covering both is either optimistic or conservative depending on which process you use. Two numbers is honest.
60% at the full 200 A is high for the price, and it is quoted at maximum output rather than at a flattering reduced current — which is the trick to watch for when a budget machine advertises a generous-sounding figure.
For TIG specifically, a high duty cycle is less load-bearing than it looks, because TIG is slow work with long gaps for repositioning and feeding rod. It matters most when you are learning and running hot.
Costs: the bundled torch is the first thing most owners replace, the manual is thin, and 50 lb plus a pedal means a permanent bench spot.
What works
- AC output is what makes aluminum possible at all — this is the cheapest widely supported machine that has it
- 60% duty cycle at 200 A is a genuinely high rating for the price
- Adjustable AC balance lets you trade cleaning action against penetration instead of accepting one compromise
What does not
- The bundled torch and consumables are the first thing most owners replace
- The manual is thin. Budget time for learning the machine as well as the process
- 50 lb and a foot pedal means it lives in one place
3. The 100% rating, explained
Lotos LTP8000
60% at 80 A and 100% at 50 A — the clearest example on this site of how a duty cycle rises as you back the output off.
Lotos publishes 20 to 80 A output; a 1 inch clean cut and 1-1/2 inch maximum cut; a 60% duty cycle at 80 A and 100% at 50 A; 210 to 250 V single-phase input; non-touch pilot-arc start; and a fitted regulator and filter with an external compressor required.
This pair of numbers is the best teaching example in the registry. The same machine is rated 60% at its maximum and 100% — meaning continuous, no cooling pause at all — at roughly two-thirds of it. Duty cycle is not a fixed property; it is a curve, and backing off the output moves you up it.
For a plasma cutter that matters more than for a welder, because a long cut in thick plate is genuinely continuous work in a way that welding rarely is. A machine that stops halfway along a cut leaves a mark you have to grind out.
Costs: 80 A needs serious air volume and starving it ruins both the cut and the consumables; it is 220 V only at up to a 50 A draw, so the circuit is part of the purchase; and consumable life does not match Hypertherm's.
What works
- A published 1 in CLEAN cut rather than a 1 in severance cut — that distinction is the entire point of this class
- 60% duty cycle at the full 80 A, so a long cut in thick plate does not become a stop-start job
- Pilot arc, so rusty and painted plate — which is what thick stock usually is — does not stall the machine
What does not
- 80 A needs serious air volume. A pancake or small twin-stack compressor cannot feed it, and starving it ruins both the cut and the consumables
- 220 V only, at up to a 50 A draw. The circuit is part of the purchase
- Consumable life and support do not match Hypertherm's, and at 80 A you get through consumables faster
Who this is wrong for: A garage with a pancake compressor. The duty cycle is academic if the air supply gives up first.
4. What a professional rating looks like
Everlast PowerTIG 255EXT
100% at 200 A TIG and 100% at 175 A stick — the specification that separates a machine that never stops you from a good hobby machine.
Everlast publishes AC/DC pulse TIG and stick; DC 3 to 250 A and AC 5 to 250 A; a TIG duty cycle of 60% at 250 A and 100% at 200 A; a stick duty cycle of 60% at 225 A and 100% at 175 A; 110 V or 220 V input; and digital microprocessor-controlled IGBT inverter control.
A 100% rating at 200 A is what the top of this specification looks like, and it is here as the reference point rather than a recommendation. It means the machine can weld continuously at 200 A with no cooling pause — the figure that separates a professional machine from a good hobby one.
225 A stick at 60% means it genuinely doubles as the shop's stick machine rather than pretending to, which is the same honest pattern as the AHP a tier down.
The reason it is a reference point: it is heavier, larger and dearer than any 200 A entry machine, and none of that helps if you weld an hour a week. That sentence is the whole argument of this page.
Costs: the parameter depth is intimidating on a first TIG machine, and Everlast's dealer network is smaller than Lincoln's or Miller's.
What works
- 100% duty cycle at 200 A is the specification that separates a professional machine from a good hobby machine — it never stops you mid-job
- Full AC parameter control on top of a 250 A ceiling, so thick aluminum is a setting rather than a limit
- 225 A stick at 60% means it genuinely doubles as the shop's stick machine rather than pretending to
What does not
- Heavier, larger and dearer than any 200 A entry machine, and none of that helps if you weld an hour a week
- The parameter depth is genuinely intimidating if you have not run TIG before
- Everlast's dealer network is smaller than Lincoln's or Miller's, which matters on a machine you depend on
Who this is wrong for: Almost every reader of this site. If duty cycle is why you are considering it, work out your real arc time first — it is usually a fraction of what you imagine.
Questions people actually ask
What does 30% duty cycle at 150A mean?
It means the machine can weld for three minutes at 150 amps in any ten-minute period, then needs seven minutes with the arc off to cool. The industry convention is always a ten-minute window.
The formula is arc minutes = duty cycle percentage divided by 10. So 20% is two minutes on and eight off, 60% is six on and four off, and 100% means continuous with no cooling pause.
Does duty cycle change with amperage?
Yes - duty cycle is a curve, not a single number, and the rating rises as you turn the output down. The clearest example in this registry is the Lotos LTP8000, which publishes 60% at 80 A and 100% at 50 A for the same machine.
That is why the stated output is part of the rating. A generous percentage quoted at a modest current is a weaker claim than a lower percentage quoted at maximum output.
How much duty cycle do I actually need at home?
Less than you think. Write down what a real job involves - measuring, cutting, grinding, clamping, checking square, tacking, welding two inches, chipping, inspecting, repositioning - and the actual arc time is often around thirty seconds in ten minutes, which is a 5% duty cycle.
A machine rated 20% has four times that. The honest exceptions are long continuous beads, the first ten hours of learning, plasma cutting, and a hot closed garage in summer.
What happens if you exceed a welder's duty cycle?
The machine stops welding. Every modern inverter has a thermal cutout that trips, usually lights an indicator, and resets when the internal temperature drops. It is a protection feature rather than damage, and hitting it occasionally is not abuse.
What does cause harm is defeating the cooling: blocking the fan intake, standing the machine tight against a wall, or letting the vents clog with grinding dust.
Why do some welders publish two different duty cycles?
Because the rating depends on conditions, and two numbers describe two sets of conditions. Hobart publishes 30% at 150 A and 20% at 90 A for the Handler 210 MVP because those reflect 230 V and 115 V operation respectively.
AHP publishes 60% at 200 A TIG and 35% at 155 A stick for the AlphaTIG 200X, because stick and TIG load a machine differently. Two numbers is more honest than one, not less.
What does a 100% duty cycle mean?
That the machine can run continuously at the stated output with no cooling pause at all. The Everlast PowerTIG 255EXT publishes 100% at 200 A TIG and 100% at 175 A stick.
It is a professional specification, and it is heavier, larger and dearer than any 200 A entry machine as a result. If duty cycle is the reason you are considering a machine like that, work out your real arc time first.
What if a welder does not publish a duty cycle?
Treat the absence as information. Several budget machines in this registry publish no duty cycle figure we could confirm, and where that is the case we leave the row blank rather than estimating one.
For short tacks and general fabrication it rarely matters. If your work involves long continuous beads, choose a machine that states a figure - an unpublished number is not a good number, it is an unknown one.
Sources
- Hobart Welders — Handler 210 MVP published specifications: 115 V or 230 V multi-voltage plug, 25–210 A, 30% duty cycle at 150 A and 20% at 90 A, 24 gauge to 3/8 in single pass
- AHP — AlphaTIG 200X published specifications: 10–200 A, 60% duty cycle at 200 A TIG and 35% at 155 A stick, AC balance 30–70%, 50 lb
- Lotos Technology — LTP8000 published specifications: 20–80 A, 1 in clean cut, 60% duty cycle at 80 A and 100% at 50 A, 210–250 V single phase, non-touch pilot arc
- Everlast — PowerTIG 255EXT published specifications: AC/DC pulse TIG and stick, DC 3–250 A and AC 5–250 A, TIG 60% at 250 A and 100% at 200 A, stick 60% at 225 A and 100% at 175 A
Read next
- What size welder do I need?
Amperage against thickness, duty cycle read honestly, and whether you need a bigger machine or a different circuit.
- The best welders for hobbyists
Machines for a few hours a month, and the three specifications that still matter at that rate.
- Best Stick Welders for Home Use
Stick-capable machines for a home shop, ranked on published stick amperage and duty cycle.
- 120V vs 240V welders: which one do you actually need?
The decision that sets your ceiling: what each supply voltage welds, and what the circuit really costs.
- The best TIG welders for professionals
Duty cycle, parts availability and repeatability — the three things that separate a working machine from a good hobby one.
- Find your level before you spend a penny
Most bad first welder purchases are not bad machines. They are the right machine bought by the wrong person, one level too early or one level too late.
Back to Find Your Level, or start over at Find Your Level.
Ryder M.
Ryder M. is the hands-on owner behind Magoo Media Group. He writes Arc & Bead's buying guides and picks every machine on the site. What every recommendation is based on — and what it is not based on — is set out on How We Pick.