Future wireless communication calls for exploration of more efficient use of wireless channel capacity to meet the increasing demand on higher data rate and less latency. However, while ergodic capacity and instantaneous capacity are fundamental properties of a wireless channel, they are in many cases not sufficient for use in assessing if data transmission over the channel meets the quality of service (QoS) requirements. To address this limitation, we focus on the concept of “cumulative capacity”, which is the cumulated capacity over a time period, and study its properties. Specifically, the moment generating function, the stochastic service curve, and the Mellin transform properties of cumulative capacity are investigated and related results are derived. It is appealing that with these properties, QoS assessment of data transmission over the channel can be further performed based on stochastic network calculus, a newly developed theory for (stochastic) QoS analysis. To demonstrate the derived properties, a Rayleigh fading channel is considered and numerical results are provided.