This is easy math you can do yourself.
Every tooth = 1/2" of sprocket circumference.
the chain only wraps 1/2 way around so it calls for 1/4" of chain
that 1/4" is divide equally between the upper and lower loops so it's only 1/8"
So, for every tooth added or subtracted, your axle will move 1/8".
Measure the usable length of your dropout, figure 1/8" per tooth, and you'll know your usable range without changing the chain.
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