Schedule variance occurs when the time needed to complete a project is different from the time scheduled for completion. In some cases projects get completed early. However, schedule variance more often refers to situations in which the timeline for completion exceeds the amount scheduled.
Schedule variance is measured by time and cost. A project phase may have a variance of eight extra work hours. If the budgeted cost is $400 per hour, the variance amount is $3,200. Significant variance between actual and budgeted project schedules is expensive for a business. If a project manager grossly underestimates the time required for a project, the business may not make any money.