Just to add though. You don't always, ( in fact with my recipe's, very rarely) , need 20% pg flavouring.
If you use flavourart single flavours you sometimes only need 3%
I think my average percentage is somewhere around 15% if using mainly TPA.
20% is probably worst case.
Because I'm having an attack of OCD I reworked the figures for 10% and 5% flavour.
12 mg nic juice with 10% flavour, the limit is 73% VG
12 mg nic juice with 5% flavour, the limit is 78% VG
6 mg nic juice with 10% flavour, the limit is 81% VG
6 mg nic juice with 5% flavour, the limit is 86% VG
Didn't bother with 3mg nic juice because the above figures for VG look high enough already.
I'm not too worried about the PG/VG I end up with as I only vape at 3mg and my flavour % rarely exceeds the 15% mark so my PG level is always pretty negligible. If I vaped above 6mg tho I probs would choose to use VG based nic coz sometimes you do add concs at 20%...lots of oneshot flavours say to use at 15% or higher so it's good to have the wiggle room if you wanna keep your juice as high VG as poss