Inverter vs Transformer Welders: The Guide You've Been Looking For

What’s better: an inverter welder or a transformer welder? Pretty straightforward question on the surface but the seemingly innocent question often leads to a debate of old versus new. One technology is a century-old while the other is basically brand new, relatively speaking (inverter welders became prevalent a few years ago).

However, the truth is there is no “best-for-all” welding machine. Both inverter and transformer welders come with their own cons and pros but the best welder is the one that fits your needs.

That said if you are in the market for a new welder and need some objective advice to choose between inverter welders and transformer welders in 2020, this is the guide for you.

What Is An Inverter Welder?

Inverter welders have various electronic components along with a traditional transformer that regulates the electric current. In other words, an inverter welder regulates the voltage so you can connect your welding machine to a 240V connection but use it at an 80V DC output. This is done through a switched-mode power supply or SMPS system that turns the connection on and off extremely quickly (up to a million times every second).

Inverter welders came to the market decades ago but back then, they suffered from reliability issues and lack of overall usability. However, the technology driving these welding machines has had plenty of time to mature so don’t let your previous impressions paint your opinion of a modern inverter welder.

Modern inverter welders have a microcontroller that allows the operator to change different characteristics of the welder to suit their workflow. Some of the things that are possible in an inverter welder include:

  • Changing and pulsing the welding current
  • Using variable ratios and changing current densities
  • Custom timings for automatic spot-welding

Benefits Of Using An Inverter Welder

Modern features aren’t the only reason why you would want to pick up an inverter welder in 2020, there are many other benefits as well. Following some of the top benefits of using an inverter welder:


Perhaps the biggest difference between an inverter welder and a transformer welder is the size. Inverter welders are compact and very portable which means they become a lot easier to work with, especially during remote projects. Just to put their size into perspective, inverter welders can weigh less than 5kg and are comparable to a small suitcase in form factor.

Transformer welders, on the other hand, are a lot bulkier and can weigh up to 50kg for a similar output. So if you plan on needing a welding machine that is truly compact and portable, transformer welders are pretty much out of the question.


Another reason to choose an inverter welder over a transformer welder is efficiency. Inverter welders have a smaller transformer as well as complex electronics that have lower resistance and heat dissipation which allows for two things to happen. 

First, an inverter welder can work with most household sockets including those with a 110v connection, and second, they have a much better efficiency rating of 80% to 90%. That’s nearly twice the efficiency of traditional transformer welders, most of which are only good for an efficiency rating of 50%.

Ideal for Casual & Beginner Welders

The combination of compact size and versatility due to complex electronics means that inverter welders are not as overwhelming as conventional transformer welders and easy to use. Furthermore, the fact that good quality inverter welders are quite inexpensive makes them easy to recommend to beginners or casual welders. 

Disadvantages Of Using An Inverter Welder

Complex Internals

From a different perspective complex internals means they are more things that could fail and this is certainly one of the biggest drawbacks of an inverter welder. The cheap inverter welders, in particular, are prone to falls and breaks (their weight and size don’t help either) which means you could be looking at more frequent maintenance. 

Not Ideal for Extended Use

Though inverter welders have longer duty cycles in comparison to traditional transformer welders and cool faster, they’re not meant for extended use that is common in professional workloads. Though the ideal option for someone looking to weld full-time will still be a professional-grade transformer welding machine, you could go with a more expensive inverter welder with better build quality.

What Is A Transformer Welder?

A transformer welder works by converting moderate voltage and moderate current (in the range of 230 and 115 VAC) into high current and low voltage ranging from 200 to 600 amperes.

Both inverter welders and transformer welders generally share a component known as a step-down transformer and this is the core part of these welders but the main difference between an inverter welder and a transformer welder is that the step-down transformer in an inverter welder is much smaller.

Benefits Of Using A Transformer Welder

The technology in transformer welders is literally centuries old with transformers becoming prevalent in the 1800s but don’t let that fool you into thinking these types of welders are obsolete. Transformer welders are still widely used and there are some pretty convincing reasons as to why you would want to use them as well.


Transformer welders don’t have a single moving part – they’re incredibly simple machines which also makes them very reliable. And while inverter welders have undoubtedly come a long way in terms of reliability, transformer welders are still superior in this department. So if you want a rugged and solid welding machine in 2020, buy a transformer welder.

Maintenance Costs

As you can imagine, transformer welders don’t break down very often (if at all) and on the rare occasion, they do need some repairing, it’s generally straightforward and simple. More importantly, it’s unlikely that you will have a problem sourcing parts and the general maintenance costs are also low compared to inverter welders.

Versatile Working Conditions

Apart from the obvious disadvantage of being big and heavy, transformer welders are quite versatile in the kind of environments they can work in and certainly more resilient than inverter welders. For instance, while you’ll want a clean, dust-free and relatively controlled environment for an inverter welder, you can use your transformer welder is a dusty, windy, and in environments with high moisture content.

Disadvantages Of Using A Transformer Welder


Transformer welders can be very heavy and large in size which can be a deal-breaker or a non-issue depending on your use cases. If your work involves going into narrow spaces or being portable at all, transformer welders are out of the question. However, if you work in a dedicated workshop, transformer welders are great. Note that the issue here is that transformer welders are difficult to move, not impossible. 


As we mentioned, inverter welders are nearly twice as efficient as their transformer counterparts which can be a big deal, especially in the long run. While lower maintenance costs do decrease running costs to some level, regular and extended transformer welding can eat into those savings and increase the overall running costs in the long term.

Lack Of DC Output (In Lower-End Models)

Inverter welders will output both AC and DC current, irrespective of their model. This is important if you want compatibility with a large range of electrodes. Most transformer welders on the other hand output in only AC current.

However, you can have DC output with transformer welders as well but you’ll need a rectifier transformer welder. A rectifier converts AC current to DC output but is usually found in more expensive transformer welders.

Consider These Things Before Buying

Understanding the pros and cons is a great way of ensuring you’re buying the right product. However, when it comes to differences between inverter welders and transformer welders, there are a few other things that you need to take into consideration.

For instance, your budget. There are some really impressive inverter welders that are equally inexpensive but most transformer welders will be even cheaper. But there’s a caveat, due to lower efficiency ratings, your electricity bill with a transformer inverter could end up eating into those initial cost savings – especially if you’re going to be using them more. Inverter welders are also more efficient with welding gasses which means you might end up doing more with less.

There is also versatility and overall usability. Inverter welders allow you to use a greater number of electrodes and gasses right out of the box, whereas you’ll need to have a rectifier installed in your transformer welder to achieve the same versatility.

Overall, the inverter technology has improved significantly and an inverter welder offers more value for the money. Therefore, we can easily recommend it to most welders. However, transformer welders have not yet faded into obscurity. There is still a large demand for transformer welding machines, especially in professional workloads because of their simplicity, ruggedness, and the ability to perform at sustained loads for longer.