A one-year sentence in a county jail rarely means twelve full months behind bars. The actual time served is almost always less, and in New York the calculation works in his favor.
New York state generally applies a good time credit that reduces a sentence by up to a third for inmates who follow the rules and stay out of trouble. On a one-year sentence that works out to about eight months served if he maintains a clean disciplinary record from day one. Some county facilities in New York also have their own local good time policies that can affect the calculation, so the exact number can vary slightly depending on how Niagara County applies its credits.
Worst case, assuming some good time is lost to minor infractions but not all of it, he is looking at something just over ten months. Best case with a clean record and any applicable additional credits, he could be out closer to eight months.
The math is straightforward but the outcome is entirely in his hands. Every incident report, every rule violation, every disciplinary issue chips away at that good time credit and adds days back onto his release date. Inmates who keep their head down, follow the rules, take any available programming, and stay out of other people's business serve the shortest version of their sentence. Those who create problems serve longer.
A year in county jail is hard but it is manageable. Eight to ten months goes faster than it sounds when there is structure, communication with people on the outside, and something to look forward to at the end.