This is an interesting point ... and I'm not sure the author of the original post understood it to this level. Mister Money Mustache's actual words are: "take y

This is an interesting point ... and I'm not sure the author of the original post understood it to this level. Mister Money Mustache's actual words are: "take your annual spending, and multiply it by somewhere between 20 and 50" (as a basis for a savings target) The key there is "annual spending". One might naively assume that the author is still aiming for the 25x savings amount based on his annual spending prior to deciding on this "retire at 39" plan. I know I sure as hell did at first. However, I see no way to do that based on the Savings Rate vs. Working Years Until Retirement chart that's presented in the post. The last line item "Savings Rate: 100%, Years: Zero" can only work if you're doing what derefr points out: continuing to live at that same spending rate for the remaining years of your life. Only by saving 100% (and thus spending 0%) could you retire instantly at any time, since you have no costs - so it wouldn't matter how much you saved. This doesn't mean the article is invalid. The author may truly understand how much of a permanent life change is involved. The trial run at 1 year may be an attempt to see how well he could live the rest of his life at a spending rate close to 1/3rd what he's accustom to. ... But reading it more and more, I'm not sure that's the case.