A Vaper’s Ultimate Guide to Volts, Watts, and Ohms

To a smoker, vaping sounds a lot like electronic engineering sometimes. Volts, watts, ohms…what does it all mean, and perhaps more importantly, why is it sooo complicated?

In fact, you can vape without ever knowing all that much about watts and resistance. As long as you’re not using an unregulated mechanical mod, you shouldn’t really have to worry about overloading your vape mod.

As long as you know which wattage settings and resistance coils you like best, you’ll be fine.

However, if you want to really understand the technology you’re using, this article is for you. Below we have everything you need to know about volts, watts, current, and battery capacity so you can really optimize your vaping experience.

Volts and Voltage
Voltage is defined as the difference in electric potential between two points. This tension or pressure forces the electrons to flow from the negative terminal of a battery to the positive one creating an electric current that powers the atomizer or heating element.
Let’s try an analogy.
If you take a pipe and run water through it, the voltage would represent the amount of water pressure in the tube. By increasing the amount of water in the tube or decreasing the size of the pipe, you increase the water pressure.
18650 batteries from most reputable e-cig brands range from 3.7V to 4.3V. While simpler devices usually fire at 3.7V, you can also find certain vape pens with variable voltage. A variable voltage vape pen will allow you to change the voltage according to your preferences.
On larger box mods though, you’re more likely to find variable wattage than variable voltage. Be careful though. Even though both metrics measure power, the two terms are not interchangeable.

Watts and Wattage
Wattage, also known as power output, measures the amount of energy consumed by your electronic cigarette. This is a unit of power used to record the rate of energy transfer of electrical current, for instance, into the heat that ultimately vaporizes your e-liquid.
You’ll notice that unlike voltage, wattage measures power consumption and not production.
Light bulbs are measured in watts as well. If you find a lightbulb that’s 100W, you know that in one hour, it uses 100 joules(a measurement of heat).
If you purchase a box mod, you’ll have to set the wattage. For most vapers, anywhere between 15W-65W is considered normal. You can find mods that can fire at over 100W, but most people find that e-cigs simply get too hot above 75W or so.
You can usually get larger clouds with a higher wattage level, but you have to make sure you’re using a high VG vape juice as well so the vapor is smooth against your throat. You also can’t raise the wattage level if your battery doesn’t support that kind of power output. We’ll get to that soon though.

Variable Voltage vs. Variable Wattage
You might notice that different devices offer different settings. On a vape pen or e-cigarette, you might find variable voltage, but on most vape mods and box mods, you’ll be asked to change the wattage. Voltage and wattage are closely related, and either way you’re changing the power level. However, in one case you’re changing the input, and in the other case, you’re changing the output.
You might think of variable voltage and variable wattage like you would a manual and automatic transmission. When you change the voltage, you’re changing the power input as you would if you were driving stick shift.
On the other hand, when you alter the wattage, you’re just setting the power output, and the vaporizer will set the voltage accordingly. Likewise, if you were driving a car with an automatic transmission, you set the speed as you pump on the break, and the car will change the gears for you to keep the car driving smoothly.
To shift between voltage and wattage, you can use the following formula W=V^2/R, or, the wattage is equal to the voltage squared divided by the resistance. You could also say that the voltage is equal to the square root of the wattage multiplied by the resistance. So, if you have a voltage of 4.0V and a resistance of 1.0Ω, you’d be vaping on 16W. However, if you lowered the resistance to 0.5Ω and kept the voltage the same, you’d be vaping on 32W.
As you can plainly see, the lower your resistance and higher your voltage, the higher your wattage will be. If you’d like to lower the heat and reduce the amount of power you’re using, you can use an atomizer with a higher resistance and decrease the voltage (or wattage!)

The current refers to the amount of energy running through the battery at any given time. In our pipe analogy, the current is comparable to the amount of water running through the pipe. You might refer to this as the flow rate.
You measure the current in amps or amperes, symbolized by the large letter A. The amperage will be labelled on the battery itself and varies greatly from battery to battery. You’ll find anywhere from 10A all the way to 30A and everything in between.
The battery’s current is particularly significant if you are planning to crank up the wattage. The wattage level your device can reach is directly dependant on the current of your batteries. Even if the package advertises that the box mod can handle up to 200W, if you’re using weak batteries, the vaporizer won’t even reach half that level.
This doesn’t change with a series connection. Box mods from most e-cigarette brands require multiple 18650 batteries. When using two batteries, the voltage will double, but the capacity will remain the same. So, if both of your batteries have 20 amps, the machine as a whole will still run on a current of 20 amps even if it’s using two batteries instead of one.

Battery Capacity
The battery capacity is essentially the battery life. This number, measured in milliampere hours (mAh), will tell you how long you can vape continuously before you’ll need to plug your device back into a charger.
So, what’s a milliampere? A milliampere is 1,000th the size of an ampere. Do you remember changing between metric units back in chemistry class? Well this is the same idea. If you take the number of amps and move the decimal point over three times to the left, you’ll get the same number in milliamperes.
A milliampere hour describes the number of milliamperes that can be drawn continuously in one hour of vaping. So, let’s say that your electronic cigarette has a battery capacity of 1,000mAh. That means that you can draw 1,000 milliamperes in one hour, 2,000 milliamperes in a half-hour, and 500 milliamperes in 2 hours.
A standard e-cig will have a battery capacity of about 200-300mAh, a vape pen will have anywhere from 600-1,000mAh, and vape mods run 2,500mAh and up.
Do note though that the battery capacity is in an inverse relationship with the current. If the battery has an amperage of 30A, chances are the capacity won’t be much higher than 1,600mAh. On the other hand, if the amperage is only 10A, the capacity will probably be well over 3,000mAh.

Resistance is measured in ohms and reduces the amount of energy flowing through the atomizer. When you lower your resistance, you allow more energy to flow through to your atomizer.
Resistance helps keeps your battery and mod from overheating and possibly even exploding. It essentially acts as a safety feature protecting you from any disasters.
With a lower resistance, you’ll get better flavor and more vapor. That being said, you’ll also wear down the battery life and atomizer faster than you would otherwise. You’ll use up your vape liquid much more quickly, and you’ll be more likely to get a dry hit especially if you’re not careful about regulating the temperature.

Sub-Ohm Vaping & Mechanical Vape Mods
Sub-ohm vaping is exactly what it sounds like, vaping with a resistance of less than one ohm. At one point, sub-ohm vaping was seen as all the rage. At sub-ohm levels, you can get more power, more vapor, and more heat. Today, sub-ohm vaping is fairly standardized. In fact, besides vape pens and small travel vape mods, most vaporizers come with at least one or two sub-ohm atomizers anyway.
Mechanical mods vape at sub-ohm levels, but not all sub-ohm devices are mechanical mods. A mechanical mod is an unregulated device created by a vaping expert designed without standard safety features. No overcharge protection, no reverse polarity protection–no protection whatsoever!
If you’ve ever read an article about a vaporizer blowing up in someone’s face, you can bet it was a mechanical mod. Under no circumstances do we recommend using mechanical mods unless you know exactly what you’re doing. Even then, there’s no reason not to stick with standard store-bought mods.

Ohm’s Law
If you plan on either using a mechanical mod or building your own coils, it is absolutely imperative that you learn Ohm’s law. Ohm’s law relates current, resistance, and voltage, and helps you determine a few key metrics.
First of all, you can use Ohm’s law to determine which battery you’ll need to reach a certain wattage level given the resistance. If your mod comes with only a few different coils, and you don’t plan to make your own, you can figure out your maximum power output by plugging in a few numbers.
If you are making your own coils, you’ll need to use Ohm’s law to figure out the minimum resistance you can use for your coils assuming the maximum possible voltage on the device and the current on whatever batteries you plan to plug in.
Ohm’s law is I=V/R, or alternatively I*R=V or even R=V/I where “R” stands for resistance, “V” stands for voltage, and “I” stands for current in amperes. So, if your atomizers have a resistance of 0.2Ω and you plan to use them at 4.0V, you better have batteries with at least 20A. Let’s say you’re using two batteries though. Then you could have a voltage of 7.0V. If you keep the resistance at 0.2Ω, you’re going to need 35A batteries to make sure you’re vaping safely.
Let’s take another example. This time, you’re building your own coils, and you want to check what resistance you can use. You can use an ohm reader to check the resistance on your coils before loading them onto your deck, but you’ll need to do your calculations first using Ohm’s law. So, you’re going to use the equation R=V/I and plug in your voltage and amperage. So, just for argument’s sake, let’s say you’re using 8.0V with batteries that offer 35A. If your coils are any less than about 0.25Ω, you’ll be in big trouble.

Do I Even Need to Know Ohm’s Law?
If this seems complicated, you can always use an ohm’s law calculator. However, do not attempt to build your own coils until you have a very firm grasp of Ohm’s law. Battery safety is extremely important, and if you try to experiment without taking proper safety precautions, you could suffer serious consequences.

What Resistance/Wattage Combination Should I Use?
Usually, your starter kit will come with a few atomizers you can use interchangeably, and the appropriate wattage range to be used with each atomizer will be marked on its side.
There are no hard and fast rules for what wattage settings work with which resistance levels, but you’ll start to notice patterns and develop your own preferences with a little bit of experimentation. Then when you decide to purchase a new tank, you can search electronic cigarettes brands for atomizers based on their resistance.
That being said, there’s really no need to use the lowest possible resistance with the highest possible wattage. Increasing power levels usually improves the taste of the vapor but not necessarily and usually only to a certain degree.
There are plenty of other factors that influence your vaping experience–the type of e-juice you use and its PG/VG ratio, for instance. If you want to improve the flavor, you could also consider using a dripper or squonk box. Moving the atomizer closer to the mouthpiece will help improve the taste dramatically.

Final Thoughts
Congratulations for making it this far! That’s a lot of technical information. Time to pat yourself on the back.
Fortunately, that’s basically all you need to know about volts, watts, and ohms even on a very technical level.. If you plan to start building your own coils, you should probably go ahead and learn how to wrap coils, but this is, essentially what you need to know in terms of resistance, amperage, and power. …And if you just wanted to know more about atomizers and batteries, then we’re glad we could help!