What’s the difference between Inverter and Transformer Welder?

Stay Welding Logo

Sharing is caring!

Transformers have been a power source for many different types of equipment, not just welders. Interestingly the first transformers were developed when electricity became more common in the late 1800s.

As it’s been used in a wide range of electronics for a long period of time, the design was perfected especially in welders between 1930 and 1980 where a ‘welding boom’ was taking place. This demand of reliable and capable machines gave manufacturers centuries to improve on their previous designs.

In the 1980s a boom in electronics started to surface, involving more individuals owning personal computers and our reliance on technology growing. As more advancements in technology materialised, engineers of welders soon realized inverters controlled by software could be used for better flexibility when welding.

As with all new technology, inverters had their teething problems. Poor reliability, moisture resistance and user interfaces to name a few. These issues have caused a long debate about which technology is best.


Transformer vs Inverter Comparison

So what is the difference, and how does this affect the end user?


Due to transformers being in use for centuries compared to inverters 35 years, there has been more opportunity for improvement. Therefore the technology is more reliable, and can be used in worse conditions whilst still maintaining performance.

For example areas with high moisture content or airborne contaminants will reduce an inverters lifespan negatively, whereas transformer machines are more resilient to poor conditions.

However it should be noted that inverter units are backed by longer warranty periods, for example Millers True Blue warranty, Hobarts 5/3/1 coverage or Lincolns 3 year warranty.

The lifetime of a transformer based machine could exceed 20 years, therefore the bar for a “long lasting machine” has been set high. The fact that manufacturers are prepared to guarantee their products for longer period of time shows their confidence, and it wouldn’t be possible if they weren’t built to last.




Both technologies can achieve great efficiency whilst maintaining arc stability, however inverter welders are superior in this instance. Inverters are more energy efficient, even having the ability to produce the same amperage from a 120V residential socket compared to a transformer welder – which will require a 240V input.

Inverters can also provide AC and DC output, even within one machine. Due to their increased efficiency over transformers they have a much more stable arc, leaving inverters the clear winner in terms of efficiency and stability.



Transformers are much heavier than inverters, as their aimed at workshop environments where portability is a low priority. Depending on the type of work you perform will quickly dictate which machine is better for your needs. It’s not uncommon to weigh over 220LBs (100KG), making it difficult to move around.

On the other hand inverter welders can weigh as little as 30LBs, making carrying easy. Some models such as the X have straps allowing you to carry the welder on your back. For use cases such as mobile welding work, a transformer machine wouldn’t be feasible to use.



Both types of welder are offered with better and better warranties, covering both parts and labour (assuming they’re serviced at a manufacturer approved service centre). That being said transformer machines are still ahead in terms of reliability due to their extensive history.

Inverters are still establishing themselves by comparison, with advancements made each time a new model is released. Therefore looking back and comparing both is difficult as inverters haven’t had the widespread usage for a long period of time compared to transformers.

However many large manufacturers provide great warranties on both types of welder, and through wide adoption through the industry inverters have proven to be dependable. Most welders produced now rely on inverters in some way showing that this technology is viable.

As they can provide a wider range of functionality, whilst also being more efficient it’s a worthwhile trade off to have a machine that can do more for less.



Welder Purchase

As inverter machines have become more widely adopted, their manufacturing cost has dropped significantly despite being more complex in design. Although machines with a lot of functionality can cost a lot more than a transformer unit, a like for like machine generally doesn’t cost any more.

Depending on the type of functionality you need, cost shouldn’t be the centre of your decision.

Although the purchase price is the same, running costs can vary a lot. A more expensive unit initially could be the cheaper option long term, therefore it’s important to weigh up both sides. When comparing machines it’s important to factor in the following:


Energy efficiency – It takes electricity to run a welder, which has to be factored into your running costs if you weld as a service. Even if it is for a hobby, you may not take kindly to raised bills for a side hobby, alongside the rest of the equipment and consumable costs it takes just to get started. Generally inverters are more energy efficient, therefore costing less over the life of the machine to run.

Downtime –Certain applications can cause premature damage to inverter welders, such as excess airborne contaminants and high moisture content in the air. Manufacturers have tried to build products more resilient to failure from environmental conditions, however they will always be more susceptible to failure.

When failure happens you won’t be able to use your machine until it’s repaired, but how will this affect you in day-to-day operations? If you’re only a hobbyist, although failure is disappointing it isn’t holding back crucial projects or affecting your income. Whereas if your equipment is crucial to business running smoothly, you have to consider the impact downtime will have.

If your environment contributes to premature failure and it’s out of your control, is it worth having a more reliable unit that’s more basic versus a versatile machine that may fail?

Potential restrictions – The general trend is transformer welders are more basic but dependable, whereas inverter welders can incorporate many different processes with reduced reliability.

Another consideration is how either machine will restrict you in the medium to long term. These units when well cared for can last a considerable amount of time. If you have a transformer based model, it’s going to be heavier and less feature rich compared to an inverter based model – would you need to purchase additional equipment in order to have the same functionality an inverter machine could provide?

Or do you need the reliability of a transformer, but also need something portable as a backup which an inverter based model provides?


Final Verdict

It’s not possible to give a blanket one choice is better than another. It entirely depends on its application, as well as your personal preference too. You may prefer a simplistic approach without all of the gadgets, or something with more bells and whistles to keep you busy.