This calculator was designed to help you determine how much an additional expense (such as having children) can add to your FI timeline. Plug in the grand total of the additional expense and the amount you invest monthly to cover it. This calculator originally appeared in the post Financial Independence With Kids: How Procreation Impacts FIRE.       Download all PoF calculators in one Excel file! You will be sent a link to the file and a confirmation to receive notifications of new posts and my quarterly progress note.