Great Fountain's maximum height ranges from about  to over . Its duration is usually about one hour but durations of over two hours have been seen. The duration of an eruption affects the interval that will elapse before the next eruption, so that if the duration of an eruption is recorded, the time of the following eruption can be predicted to a precision of about two hours.
Great Fountain's peak elevation fluctuates from roughly to above . Its typical duration is about one hour but has been observed for up to two hours. The length of an eruption impacts the interval before the next eruption; therefore, if the eruption duration is noted, the timing of the following eruption can be estimated with a precision of approximately two hours.