I’ve read quite a bit about very knowledgeable people and spent quite some time on the Steam Engine calculator, but haven’t found yet a clear answer to my puzzle. For months, I have been building many coils from a Clapton wire 32ga wrapped over 26ga using a 20 post and 5 wraps to get a target resistance of 0.5 ohms just about every time and for my 80% VG liquid, I get a perfect setting for my taste. The problem is that threading the cotton wick through the small inner diameter is a pain you know where, so I’d like to use a size 25 post instead, but not sure if I should have more or less wraps? I guess I could always try one and test it with my ohmmeter, but I thought I’d just ask before I fry something or get an unexpected result.
I don’t build claptons anymore. I usually build 2.5 to 3.0 mm ID single wire coils. When I build the 3 mm ID coils I use 1 less wrap than the 2.5 mm ID coils and usually hit the same ohms.
I have no idea what a “20 post” is o.O must be imperial? Anyway, when you increase the inner diameter you should use less wraps to achieve the same resistance, assuming the same wire. Be aware, though, that your vape experience might change if you do this. 
I am guessing 20 is 2.0mm and 25 is 2.5mm.
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Seems legit. 
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From the numbers you listed it looks like 26ga N80 core with a 32ga kanthal wrap. A single 5 wrap around a 2.0mm inner diameter coil should yield a .515 ohm coil. A 4 wrap of that same wire around a 2.5mm inner diameter should yield a .472 ohm coil. Hope that helps.
JoJo you are right and I am sorry I didn’t write it in the question. Thank you for correct guess 
and thanks to everyone for their help. I ended up just trying with 4 wraps and of course everyone was right, I got 0.48 ohm on 4 wraps @ 2.5mm which made it easier to thread my coton wick without ripping it once in a while 
Resistance is total length of wire. Given a set length. Increase the diameter and it wrap less. Ok I can’t help it I am left-handed.
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Why not just move to that larger ID and keep the wraps. Your ohms will go up but the vape may be awesome. Don’t know if you’ll like it if you don’t try. I’m guessing flavor and vapor both would be slightly improved.
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Excellent idea SthrnMixer! and I will try it on my next one, not really sure why I am stuck on 0.5 ohm, maybe I got misinformed at some point and I actually never tried raising the resistance. Anything to improve the experience even slightly is worth a shot. Thx
Pro_Vapes > Only reason I am using a Clapton wire is that using 80% VG, I thought they would last a bit longer than a single wire before getting clogged up.
If the ohm’s are too high for you when you go up in diameter, you can always reduce the number of wraps to bring it back down or even go lower, if you want. It’s where your happy at with your vape.
But you can also space your wraps and a "spaced "coil gives more flavour in my opinion.
Your 20/80 mix should make no difference in the larger diameter but could wick slower in the smaller diameter. But I’ve had no problems.
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Think you guys are on to something. More wraps increases surface area. This will change your vape. Play with wattage and hopefully find your sweet spot. Lately have been playing with coils with a noisy cricket a good vape with higher ohms is possible.