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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28.03 11:07

I’m using a kanger subox mini…just built a dual coil reading at .2 ohms firing it at 30watts…with a goon rda…would it be safe????

Because the manual says the mod should not fire lower than .3 or maybe it says that .3 is it’s sub ohm limit???

gunadil saleh
19.03 04:19

very invormative

10.03 01:17

My ohms are adjustable on my smok mod box. Should they be set at the same number as the number on my actual coil.

05.03 11:36

Use this a lot just to double check I’m safe thanks guys and if u don’t know what ur doing u should get advice from professionals who know about them before u use anything

12.02 23:39

I have a smpl vape with the normal stock stuff on it and I have no idea how to fix it whenever I press the button it has a lot of smoke a loud crackling noise and all I smell is coil when it didn’t used to do that and idea of how to fix?

09.02 14:13

I have an 80W Eleaf istick power with the tfv4 mini. The watts are at 35 and the ohms is reading 0.74. I have a TF-RCA coil on it. Is this safe?

28.01 04:12

Running a kooper box mod with a arctic horizon tech tank at 60w with a BTDC 0.2 coil 0.20Ω not to sure about the Ω as i went off of what my coil said from the research iv done when i know what watts i need my mod at to vape safe but dont really understand my resistance.. Any ideas? Thx

22.01 05:51

Very informative

21.01 04:43

ian you have to care a little bit and understand some parts of vaping or you will mess things up and get hurt, your ipv5s will do most of the work for you, so on the calculator put in 100 watts and then the ohms of your coils, if you don’t know them you really should if they are pre made they will definitely tell you what ohms they are, if you made them then when you put it on your ipv5s it will tell you how many ohms the build is its that simple somehow you have to know the ohms there is no way that shouldn’t or actually there is now way that you can’t know it everything is told to you

Mike S.
21.01 04:37

you guys that have all these weird questions are scaring me that you vape…a lot of people on here are using the calculator correctly just to double check or to make sure what they should be running at…most of the questions are if i have this ohm coil what should i go to? most of the coils tell you what they are suitable to run at they will say 20-30 watts right on the coils or in the packaging…if you are making a coil to put on your rda if you are using a mech mod and you don’t know what to vape at please don’t use one…get an electronic one…because it does the calculations for you…i have a ipv 5s until i go up and get the 8 i have the aspire clieto…the coils it comes with are .2 and .4 ohms…on the coils is says what the limit is…the .2 is 55-70 so just put your wattage dialed in between those settings and you will be fine…and your mod will tell you how many volts its using but if you have batteries that are good for vaping which there are like 10 right off the bat you can think of then your are fine…the mod will tell you what ohm your build is…if you just made a coil yourself like a 5 wrap 22gauge kanthal…the mod will tell you how many ohms you just built it for and then dial in the wattage until you find a setting that suits you for clouds and/or flavor thats it…but most of the people on here know what they are doing i give props to you guys/gals

19.01 13:58

To all the guys asking if their setup is safe…..take the amps value that the calc gives you and check that your batteries are rated for that discharge rate. Safety is dependant on your battery ratings, nothing else. (beware of fake/cheap chinese batteries and their quoted specs)

18.01 19:17

When I push my button it blinks 9.9 and doesn’t work. KBox nano with a 1.2 coil

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 ??