The calculator developed by former hospitality worker Natalie Tindale and Professor Drew Dawson, director of the Centre for Sleep Research at the University of South Australia, will sell as an iPhone app for less than $50 at iTunes beginning September.

The calculator will also be made available on touch-screen kiosks at service stations, fatigue rest stops on highways, truck depots and selected work sites.

The application's ability to score one's fatigue level and recommend the corresponding amount of sleep before working or driving could help reduce road and workplace accidents related to lack of sleep.

According to Dawson, fatigue is one of the top four causes of fatal road accidents. The other three are drink driving, speeding and not wearing seat belts.

Tindale came up with the idea of a fatigue calculator after experiencing micro sleeps while driving after working 12-hour shifts for 14 consecutive days.

Such an app is important for someone like Nicole Seeney, a law student at Queensland University of Technology. The 23-year-old said the calculator helps in informing him if it is safe to drive after a long day.

Seeney works full-time as a property broker and studies law full-time at QUT so he wakes up early and sleeps late.