In one implementation, a volatility of expected service usage is calculated along with an expected revenue. User input provides estimates of service usage such as an estimated high usage, an estimated low usage, and a swing range of percentiles for the high and low usage estimates, for each time period in a plurality of future time periods. A user also provides a schedule of prices that are based on usage rates. A model volatility is calculated based on the swing range of percentiles, the estimated high and low usage, and a cumulative density function, such as a cumulative lognormal density function, for each time period in a plurality of time periods. The expected usage and the schedule of prices, along with any discount plans, are also used to calculate an estimated revenue.