Tutorial: Ohms Law and Vape Safety Calculator

Tutorial: Ohms Law and Vape Safety Calculator

Overview of Ohms Law and Vape Safety

Mechanical mods, high wattage regulated mods, rebuild-able dripping atomizers and rebuild-able tank atomizers are becoming extremely popular. Most experienced vapers quickly realize the cost savings of rebuilding and make simple RDA's / RBA's and RTA's part of their daily life. It's no surprise - for the cost of a pack of coils you could buy a year supply of kanthal wire and organic cotton - the building blocks of most vape coils built today. Additionally, self build coils in RDA's tend to produce a lot more vapor and superb flavor over traditional coils, but this post is not about that.

This post is about vaping safely and what that means. Let's face it, a metal tube with a high voltage battery or a high wattage (think 150W) box mod with two is nothing to smirk at. You are putting that thing right next to your eyes, mouth and face and firing (activating) it. You WANT to be safe! Before building your first coil, it is highly recommended to buy an ohms meter. This is a device that will tell you the resistance of the coils on your atomizer. Armed with resistance (Ω) you will be able to easily figure out if your setup is safe. But first, what exactly is "safety" when it comes to mods and e-cigs? Easy, the batteries used today for most mechanical and box mods are either 18650 or 26650 series batteries. These batteries vary in Amps - amps are batteries' ability to discharge stored energy (current). When a battery is pushed above its limits, the battery can vent, which means hot chemicals exit the battery under very high pressure or the battery could blow up. Yep. It's as scary as it sounds. That's why you should never push a battery beyond its capability. You should always check the resistance of your coil and calculate the amps the coil will pull from the battery, using either the volts for mechanical mods (4.2 for most 18650 and 26650 batteries) or watts you will set your box mod to. Sub-Ohming is easy and can be done safely, as long as you follow the simple guidelines above. For those of us not in favor of doing the math on our own, we built a handy Ohms Law Calculator in our signature easy to understand style. Notice, each variable is color coded to represent a piece on the mod below.

Vape Ohms Law Calculator

To use the Ohms Law Calculator to ensure vape safety, enter any two variables in their respective boxes and hit calculate. If the AMPS value comes out higher than what your battery is rated for, adjust either Ohms on your coil build or wattage output on your box mod.

Enter any two variables

For the mathematically and scientifically gifted out there, Ohm's Law defines the relationship between power, voltage, current, and resistance. The various possible formulas for Ohm's law are as follows.


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06.01 15:14

Is a 1.6 Ω coil vaping at 30 Watts but showing 6.9 Volts safe?

06.01 13:44

I recently bought my girlfriend the same setup that I have. I use a kbox 200W with two IMR 18650 3.7v 2100mAh 30A/60A batteries and a Smok Cloud Beast tank with a quad coil that sets up at .14ohms. She’s been doing so much research that she thinks the whole thing is unsafe to use. How would I go about proving it is safe?

02.01 22:29

how many rounds of the coil should be at 0.26ohm?

21.12 22:23

Nice thanks the site

19.12 00:37

i have alien mod with 2 awt batteries ( 3000 , 40A) kanthal wire 10 loops with V=5.73 ohm= 0.777 Amps=7.393 with watts on 40, should that be safe or not ?

Ian singer
28.11 22:30

What do I set my ipv5s resistance settings and stuff at just to keep it at 100 watts? I’ve been vaping for a little bit, but am really not interested in builds and usual vape stuff. I just don’t want to get hurt by my damn vape. I use regular coils nothing special.

21.11 03:35

Not REAL NEWBIE, but now totally confused with this calculator… I have 3 different sized eleaf mech mods.. 20w, 30w and 40w.. I use Kangertech Nano and the next size up (mini?) I use 1.2 coils in the 20w & 30w and .5 in the 40w now I pit the number of the coil in the OHMS orange box and the highest rated watts in the watts yellow box (or am I sup to use the setting I vape at in this box?) Now what is the answer sup to be for ? Is this the setting they suggest to use? Or lowest ot highest setting? Say I’m using my 20 mod with 1.2 coil I normally have it set at 9w.. the calculator says 15.40.. is this where I shud use it ? Or not go above it ? Confused..Please help me !! Vaping for 2 years and still don’t know if I’m doing anything right !!!

Ryan Janson Mercurio
19.10 09:14

I’m a newbie at vaping and would like to know the min/max coil ohm reading suitable for a tube type vape. Any suggestions? Somebody told me that I shouldn’t build as low as .19ohms. Is this still safe? Thank you guys in advance.

13.10 18:26

This is a great calculator! I use it every time I switch atomizers on my Joyetech Cuboid 150w. I’m a newbie, sort of, and I’m terrible at math, so an easy to use calculator like this one is a gift.

One warning; As usual, I didn’t read all the instructions above the calculator carefully, and until today I was matching volts and ohms, without doing this: " If the AMPS value comes out higher than what your battery is rated for, adjust either Ohms on your coil build or wattage output on your box mod."

Fortunately, even when not watching that I didn’t exceed the rated amps, the wattage value came close to the “safe” range. Now that I know not to exceed the amps rating, I feel less like a dummy.

Joey w
09.10 14:17

I have a single 6 rap 22 gage.. Thats.28 ohms. What should my wattage should be at?

Rahul Singh
30.07 03:22

Two 300 V dc voltmetets having resistances of 15000 ohm and 5000 ohm are connected in series.The safe voltage which can be measured by this combination is : plz anyone solve this problem.

John gray llicardo
22.07 02:50

Ohms law

Allan M. Pabuhat
13.07 19:59

i have a ohm reading of 0.17 dual coil clapton 6loops build, vaping at 70watts,isn’t it a little weird that i have a low resistance ??

03.07 09:58

Basically to insure safe usage just make sure your amp draw is less then the amp rating of your battery. My samnsung vtc4 is rated for 30 amps, with a watt setting of 25 and coil resistance at .24 ohms my amp draw is 10A well withing the limit. The actual mod you use shouldnt affect this. Look up your battery, find its amp rating and then make sure your amp draw is less than that rating with a caulculator like this one and you should be good to go.

24.06 09:37

Is it ok to have an .15 ohms?

17.06 04:48

So as long as the amps is lower than the 22amp limit of my samsung 25r, then I am safe? Should I not worry about my volts exceeding the 3.6v nominal voltage written on my battery?

07.06 01:45

That’s a really good way to show this I am happy they got this like this to teach u things

Fahim Faysal
01.06 14:01

My dual coil is showing 0.26ohm resistance,what watt should i vape it on in vaporesso tarot 200w device?

Joseph Surgent
27.05 17:20

To better explain what i mean i just a .18 ohm dual coil which ohms law formula would be the best to use to determine the max wattage i can vape at. I tried the watts/res square root and got 33.6 amps keep in mind i am running 2 18650 batteries at 25A each is this safe since im below 50 or do i need to keep the amps under 25 i hope this makes a bit more sense than my previous post


Joseph Surgent
27.05 17:13

I have an xcube 2 running 2 18650 batteries at 25A each does this mean that i can push a total of 50A safely or is 25A still my target limit does the amp outpit double since I am using 2 batteries or do i look at what each battery can output independently


22.05 03:20

I have a build that is reading .06. Is this even safe to vape and if so what can I vape it on. I don’t know what’s to low.

Jedi... leader north section
10.05 22:53

Hey I got a Fuchai-200w mod. I twisted up some 24 gauge wire and got some crazy action. First had 6 raps. Then cut it back to 4 raps. Got down 6 to 5 ohms at 60 to 70 watts. Great taste my two 18650 batteries have not heated up yet. It took me 30 minutes to build it. For now I am happy I will keep an eye on the battery heat and noise.

10.05 17:51

I bought noisy cricket with indestructible rda. Its a series mech mod. What build should i do? And what mm and loops of coil?

Kaleb marden
26.04 12:07

I have a Samsung battery and a smpl mec mod what ohm coil should I make?

06.04 21:56

If i buy pre-made coils will the resistance change after I clip the leads? And when calculating the power do I add the resistance of both coils?