The last time you probably took notice of Ohm's Law may have been in a high school science class, but if you've searched for this blog in particular, or looking to gain a greater understanding of Ohm's Law in relation to vaping, then it's time refresh your memory with the concepts of Ohm's Law as you move further in your vaping journey.

Although this blog goes into great detail to provide you with enough knowledge on safe vaping, you should always ensure you carry out the correct calculations and never push a battery or device above it's recommended/calculated potential. 

This blog is an extension to our battery safety blog and covers the basics with useful information on safe vaping including a tutorial on how to wrap/re-wrap your vaping batteries. 

Why vapers should understand Ohm's Law

By having a basic understanding of Ohm's Law, you'll learn more about power and wattage which is the most common way to measure your vape kit performance. Most importantly, knowledge of Ohm's Law can provide vital information regarding vaping safety and in turn prevent any hazardous actions.  

When looking into unregulated mods (talked about further on) it's important to fully understand Ohm's Law, not only to protect your device but also to ensure you do not injure yourself by over powering rechargeable batteries or coils

Understanding The Basics

Simply put, Ohms Law is utilised to determine current, voltage and resistance in any circuit. With a vape kit being an electric circuit itself, it functions like any other circuit with your vape device most likely having a variable setting allowing you to adjust each of these aspects individually, mostly wattage. 

Current, Voltage, Resistance and Power

Before going further with Ohm's Law, it's important to understand the main components which for around it and how they can each in turn effect your vape:

Current (I)

Measured in Amps (A), current can be viewed as the rate charge flows through a surface, such as a wire. This current is normally what we think of when we think of electricity. The movement of this current also works through electronic devices such as vape kits.

Voltage (V)

Measured in Volts (V) and can be viewed as the difference in charge between two separate points, mostly thought of as positive and negative terminals on a battery. By having a greater voltage between these two points, more energy can be created with the same amount of charge when in comparison to that of a lower wattage.

As you may have noticed already, the majority of vape kits on the market today have the ability to change voltage with a variable voltage setting. It's important to understand how the change in voltage can effect your vape and this blog will look into the fundamentals for you to gain a greater understanding. 

Resistance (R)

Something you may be used to, resistance is measured in Ohms and can be understood as a materials tendency to resist the flow of current. By having a lower resistance, current can flow faster and easier when in comparison to a higher resistance. Depending on the resistance you will notice you can get a completely different vape with these changes.

Most vapers will be aware of the term "sub ohm" in the current vaping climate and by understanding resistance you can further understand how sub ohm kits work. Sub ohm literally means having a resistance of less than one ohm. 

Power (P)

Electrical Power (P) is measured in Watts (w) and is defined as the amount of energy hat is used within a current. Power has one of the greatest influences on how vaping can be changed. As you may now possibly be aware, the higher the power, the quicker your vape warms the coil and in turn provides a quicker and warmer vape overall. 

Ohms Law Power Triangle

If you're still confused and feel as though you're going to struggle to understand Ohm's Law in depth there is no need to worry. The entirety of Ohm's Law can be calculated a lot easier with the help of the Power Triangle (see below). 


As you can see within the Power Triangle above, there are three main elements to consider and this goes for any electrical circuit represented by the letter V, I and R.

The easiest way to remember the order of the triangle is "V over I times R" with "times" being multiplication. For many the hardest part is remembering which letter means what which can all be found below:

  • V = Voltage (Battery Voltage)
  • I = Current (Amperage Drawn By Coil)
  • R = Resistance (Resistance in ohms of your coil)

To work out the desired equation, simply cover (or cover imaginarily) what you're trying to work out to reveal the equation to work out your answer. Once you have the equation it will be a lot easier to calculate. If you need additional help you can now use our simple Ohm's Law calculator at the bottom of this blog! 

So know with the basic understanding of the Ohm's Law with thanks to the Power Triangle, it's time to work out how to calculate current, voltage, resistance and power. By understanding what we cover in this blog, you'll become a lot more knowledgeable to start building coils, using unregulated mods and safer vaping in general. 

Calculating Current

If you're trying to work out the current draw though a resistance (coil in this case) the following formula is how to go about it:


It's all well and good knowing the formula, but if you're still struggling let's put this into a real world scenario. 

If you were using a mechanical mod with a fully charge battery you will essentially have 4.2V available to power through to your coil. If you were using a coil of 0.6ohms, you know have everything you need to work out the equation:

I = 4.2V ÷ 0.6ohms or (4.2 / 0.6)

I = 7A

As you can now see, with a 0.6ohm coil and fully charged battery of 4.2V the resulting maximum current draw will be at 7A. If your battery was to have a standard 10-amp limit then you would be well below the cap!

Important to remember

Ensure you don't forget that if you are using a dual mod in a series configuration then your amp draw per battery will be doubled, therefore you would have to build cols with double the resistance to ensure you create a safe vape.

Calculating Resistance

Using Ohm's Law to calculate resistance is another important factor within unregulated mod vaping. Mostly used to calculate the lowest coil resistance possible you would use the following equation:


Knowing that the battery CDR as above is 10A, it's ideal to aim slightly lower when working out resistance to give yourself a little headroom when calculating. Also by using the same calculations as above, you know your max voltage is 4.2V on a single battery mod too. Calculating resistance for this looks like:

R = 4.2V ÷ 9A or (4.2 / 9)

R = 0.47ohms

Once again in this scenario the results highlight that you are well within a safe range with a 10A battery however anything lower could risk exceeding the current limit on the battery. 

Calculating Power (Wattage)

Although not shown within the generic Ohm's Law Power Triangle, calculating power is an important equation when calculating how much power is generated at the coil, or wattage. We've created a mock-up for the equation to calculate power with Ohm's Law as follows:


Continuing with the same factors as above, calculating power can be seen in our example as follows:

P = 4.2V x 7A or (4.2 x 7)

P = 29.4W

By looking at the equation above, it's clear to see that with your same 0.6ohm coil and fully charged battery at 4.2V and maximum usage of 7A will deliver 29.4W. Remember that when the resistance of your coil(s) increase the current and wattage will drop. 

Calculating Voltage

Probably the least useful when using Ohm's Law in relation to vaping there is the equation to work out voltage. Like all the previous equations, as long as you know the other two variables, calculation is easy with the following equation:


Although as highlighted, calculating voltage isn't particularly useful when in regards to vaping, however it's nice to share the example of how this would be done. Using the same factors as we've found out with all the previous calculations, the voltage can be calculated through the following:

V = 7A x 0.47ohms or (7 x 0.47)

V = 3.29

Regulated Mods

The technology made available nowadays makes picking up vaping a lot quicker, easier and safer thanks to regulated mods and more noticeably, starter kits, AIO kits and sub ohm kits.

Regulated mods  are, well.. regulated which means you don't have to worry about Ohm's Law, although it is still ideal to have a basic understanding for your own knowledge and safety. 

Although regulated mods are created to provide a safe vape for you, it's still vital to ensure you look after your device and most importantly take extra care with rechargeable batteries to prevent any damage or injury. If you haven't already, we strongly recommend you read our blog on battery safety with wrapping tutorial. 

What tends to happen for many is that interest into the vaping world grows and then experimenting with more advanced vaping equipment begins. The most common move is into unregulated mods (see below). 

Unregulated Mods

As you extend your knowledge further into the vaping world you may move onto unregulated mods. This is where all your knowledge of Ohm's Law will really come in useful to ensure your safety and vaping experience. 

Unlike regulated mods, unregulated mods are not regulated as the name suggests. This means you're able to push your rechargeable batteries to their limit to get the most power. Although having this complete control over your device is great, it's also possible to push the batteries further than they are capable of which can result in severe injury in worst cases.

In addition to this blog, we also strongly advise you read our battery safety blog to gain a greater understanding of safe vaping overall. 

Ohm's Law vape calculator

To make your life a lot easier, we've included an Ohm's Law Calculator so you can get back to the most satisfying part of vaping, the vape! 

Enter two known values and press Solve to calculate unknowns.





Summary of Ohm's Law and Vaping

If you're not technically minded, you may still be confused with everything you've just read and that's totally understandable it's a lot to take in at once! 

If you haven't already, the use of our Ohm's Law calculator above will take away the majority of equations you'll have to carry out yourself although you will still need to know the figures before you can calculate. 

Realistically there are three useful formulas to calculate for vapers; calculating current (I= V/R), calculating power (P = V x I) and finally calculating resistance (R = V/I). These calculations will allow you to work out the current your coils will draw alongside the wattage that will result.

As you increase resistance, current and power will drop off, whereas if you decrease resistance, both current and power will increase. By using the resistance equation, you will be able to calculate a safe low resistance for your battery. 

Final Important Information

One final important thing to notice is to always assume your vape battery voltage is equivalated as a fully charged battery, which is normally 4.2 volts for a single battery or parallel battery mod or 8.4 volts for for a dual series vape mod.

Although some will state that your coils will not see the actual battery voltage due to drop, it is always the safest way to utilise the theoretical battery voltage in all your calculations. 

If you still are unsure, we highly recommend that you do not jump in with unregulated mods right away. If you're still new to vaping there is still a wide range of regulated mods available to start experimenting with while you start to understand Ohm's Law a little better.

If you need any further advice leave us a comment below or reach out to us directly and a member of a team will be more than happy to give you safe and expert advice! 


But for now, as always; Stay safe and speak to you soon,

The Royal Flush Team! 

Disclaimer: The content on www.royalflushvape.co.uk offers general insights about vaping and vape related products. Please be aware that this information is not meant to be a substitute for medical advice and should only be relied upon when explicitly referenced. We make no guarantees regarding the accuracy, reliability, or health-related advantages of the content displayed across all pages of our website, including blog posts, product pages and social media content.

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