100mg is the easiest to ratio out.
I am going to preface the rest with a warning/disclaimer.
100mg nic is very dangerous to work with.
Don't get lazy or complacent.
Never mix juice if you are im a hurry.
Mix your juice in an environment free of distractions.
If your phone rings and you are moving fluids, just let it ring.
You can call the person back.
But you can't undo putting your phone to your face with nic fluid on your hand.
Do everything slowly. No fast movements. You don't wanna fling 100mg nic around.
Wear gloves and eye protection. Long sleeves are good too.
I keep an emergency saline eye wash near my mixing station.
If you get juice on yourself, wash it off immediately.
Ok, now that's out of the way.....
So easy, it's one of the reasons I use it.
I never use an ejuice calculator.
I've never tried to up the nic level, but find my ratios very to use when mixing juice from scratch.
This will get you right in the ballpark.........
Example, if you are using 20ml bottles, and are going to use 6mg fluid as your base, you add 2ml of 100mg to the bottle, and 18ml of your pre mixed juice.
That'll get you 16mg juice.
Just remember, it's really easy to divide by 100.
If you have a 60ml bottle, add 6ml of 100mg nic, and 54ml of your 6mg juice. That gets you 16mg.
10ml bottle you would add 1ml and 9ml of the premix.