If you maintain an abode in Ohio and have at least 213 Ohio contact periods during the tax year, you are presumed to be domiciled in Ohio for the entire year. This presumption may be rebutted only with clear and convincing evidence. An Ohio contact period is not the same as a calendar day: it generally involves being away overnight from an abode outside Ohio while spending at least part of two consecutive days in Ohio. The app counts calendar days, so this rule provides an approximation rather than an exact legal calculation.
https://codes.ohio.gov/ohio-revised-code/section-5747.24