That would be right for 18mg nicotine target level with the assumption that you are inputting 10% flavoring. (Since "mg" is shorthand for "mg/ml" it's important to know how much, ml's, you're planning on making.)
If you do the double check math and include the designations 7.5ml * 24mg/ml = 180mg (The ml below the / is cancelled by the ml of the 7.5 so you just end up with mg's) If your total volume of finished liquid is 10ml and it has 180mg's of nicotine then 180mg / 10ml = 18mg/ml. So that checks. You posted 7.5ml and 1.5ml which adds up to 9ml and 10% flavoring in a 10ml bottle is 1ml. 9ml + 1ml = 10ml which is why I based my assumption that you were making 10ml at 10% flavoring as it makes
sense with the 180mg of nicotine.
If you want to figure your final PG/VG ratio just take your PG's and add them up and compare to the VG. 7.5ml of PG nic, (half of the 1.5ml PG/VG since it is 50/50) 0.75ml of base, and 1ml of flavoring for 9.25ml PG and 0.75ml of VG for a final 92.5/7.5 PG/VG ratio. (10ml is the final total so it is a simple matter of shifting the decimal one place.)
You'll have to make it and tell me if it needs to be sweeter before I'd have a clue as to if it needed sweetener, but if it seems to need to be sweeter to you, I'll bet you can make that call without me.
What are you making? Be sure to report back what you discovered with your first mix.
