Employment and working conditions are strong social determinants of health, yet many epidemiological studies fail to account for their impact on life expectancy calculations. Integration of working conditions into health estimates requires both valid methodology and data sources. Using the French National Health and Career Path survey and French life tables, we quantified the impact of four major work-related factors (lack of job control, job insecurity, unemployment, and occupational physical activity) in explaining socio-occupational inequalities in life expectancy. Using a formula-based approach, we computed work-related loss in life expectancy by socio-occupational group separately by sex. Based on life expectancy at age 35, we estimated a range from 1.3 to 3.3 years of life lost for men, and from 0.5 to 1.8 years for women are attributed to a combination of these four key factors. Although subject to sources of under- and over-estimation, the differential life expectancy at age 35 between senior executives and manual workers would substantially decrease, had these exposures been set at the theoretical minimum level. This proof-of-concept analysis demonstrates the utility of accounting for occupational factors and the potential to quantify the improvements in life expectancy by modifying working and employment conditions.