I've been making my own
juice for so long, I eyeball stuff now. You'll get to the point where you'll be able to do that also. As with anything, it just takes practice to get better at it. Stick with simple mixes at first like one or two flavorings to begin with. I wouldnt start out trying to make a serial killa clone for your first batch. lol. Juice me up calculator definitely helps but its just math and knowing your extracts. Most berrys and fruits are about 10%mixes. most tobacco's and menthols are usually much less, more like around 2-5%. So if you making a 10ml bottle of strawberry e liquid, you'll want to put about 1ml of extract in. fill it the restof the wayup with your premixed pg/vg nic no flavoring base, shake and vape. Start outwith small batches to begin with because everyone tastes are different. You'll do fine, welcome to ECF and the world of DIY'ing your own juice!