Purpose – This paper summarizes a time-diary study of a Canadian public library that estimated the hours spent by patrons using library facilities and circulated collections during a month. The purpose of this paper is to convert conventional library statistics into a metric more understandable to external stakeholder groups: time. Design/methodology/approach – Paper-based time-diaries collected data on the patron use of circulated library materials throughout the loans cycle and exit surveys measured the duration of branch visits. This data along with gate and circulation statistics were used to estimate hours of patron residency in library branches and the time spent consuming borrowed materials. Findings – Patrons used the services, facilities and collections of Prince George Public Library’s Bob Harkins branch for an estimated 182,000 hours during August 2013. Over 90 per cent of use occurred offsite through the consumption of circulated materials by diarists and secondary use of borrowed items by their families and friends. Practical implications – Conventional statistics understate the utilization of public library resources as most of their use occurs outside the library branches, a different usage pattern than for other municipal services. This study suggests that all library use is potentially measurable using a single metric, hours of patron use. The value of a time metric, once methodologically sound, is its usefulness as a measure of library performance and its convertibility in dollars of direct value using contingent valuation methodology. Originality/value – Time-diary methodology collected patron time-use data on public library circulated materials. The paper demonstrates the potential of patron time-use as a metric of library performance. Hours of patron use appear convertible into dollars of benefit using contingent valuation research.