How it works
Start with the income your family would be short each year: the share of your take-home pay they would still need, minus their other income. The lump sum pays that at the start of each year, rising with inflation, while the rest stays invested; it runs out after the last year they need it. Add the mortgage and other debts, final expenses, an education fund per child and an emergency fund, then subtract savings and the cover you already have. In the example, a $70,000 take-home pay, two children and a $280,000 mortgage need $1,075,149 in all; with $45,000 saved and $140,000 of cover through work, the gap to buy is $890,149. The 10× rule says $700,000 and DIME says $1,693,000, because neither looks at what your family would really need. The spreadsheet adds a year-by-year table that shows the lump sum lasting exactly the years you entered.