Understanding the duration of widowhood is essential for individuals and effective widow support policies. However, widowhood duration (WD) remains an understudied topic. In this article, we provide a quantitative estimation of the impact of three primary determinants of expected WD at age 60 within a unified framework: (i) the degree of overlap between male and female mortality distributions; (ii) the age gap between spouses; and (iii) the dependence of spousal mortality. Using French life tables from 1962 to 2070 and simulations based on the Gompertz law and a bivariate Gaussian copula, we assess each determinant's relative influence. Our findings show that ignoring spousal mortalities dependence overestimates WD by three years, while disregarding the age gap underestimates it by one year. In France, in 2020, expected WD for females at age 60 is 10.4 years and 5.8 years for males. Despite converging gender life expectancies, our projections suggest that WD will remain high until 2070: 9.2 years for females and 6.2 years for males. Notably, we identify a negative gradient of WD along the standard of living distribution.