A man who retired at 34 shares a spreadsheet that helped him get there

The 34-year-old software developer and blogger behind the Mad Fientist - who doesn't use his last name online for privacy reasons - had been planning and saving to retire early for years.

"For the first five to seven years of my career, I wasn't saving for anything in particular," Brandon told Business Insider. "I was just saving because I wanted a portfolio. Then I learned about financial independence, and I was like, 'This is perfect. This is what I'm saving for.'"

Brandon, who is married but keeps his finances largely separate from his wife Jill, an optometrist who isn't interested in retiring, was talking about the concept of financial independence (FI) as pursued and documented by an online community of bloggers and readers seeking to save enough that they can stop working and "retire."

Living frugally and working in rural Vermont, he managed to save and invest about 70% of his after-tax income, and saved enough to leave his job in the spring of 2014. However, when he approached his employer with the news he'd be moving to Scotland to be closer to his wife's family, they offered to make his position remote.

That change eliminated all of the things that most frustrated Brandon about working life, like commuting, dealing with difficult coworkers, and navigating endless meetings. So he stayed on for a few years more than planned, intermittently traveling with Jill until they relocated full-time to Scotland in May 2015. There, he continued working, blogging, and saving until he retired this summer.

"It's always been about 'financial independence' for me and not really 'early retirement,'" he told Business Insider. "I never wanted to stop working, but rather I wanted to have the time and freedom to work on things that are important to me. It's a very powerful position to be in, to be able to do things without worrying about the monetary reward, so I imagine I'll be more productive and make a far greater impact on the world now that I don't have to trade my time for money and don't have money driving my decision-making."

On Mad Fientist, Brandon offers a free, downloadable Excel spreadsheet to help others calculate when they can afford to retire. It's not the exact one he currently uses - since he built this version in 2014, he's made some tweaks to his own - but lays out the most important factors, accounts, and balances he's been tracking for years. Bear in mind that the numbers in the sheet are not his actual numbers, which he does not share. These numbers are being used for example purposes only.

The blue cells are the ones for individuals to edit (on the interactive version from the website - below are screenshots that don't accept data) to input their own numbers.

Below, he walked Business Insider through the spreadsheet: