This is relevant to those who reach their FI number and then want 'one more year' or otherwise start to feel it's now not enough. Your FI number is your FI number, but it isn't. When I initially computed my fire number I didn't account for inflation. Yes, 4% accounts for inflation over the retirement period. BUT if it takes you 15 years to reach your number as computed by your current living expenses, your cost of living has gone up in those 15 years at minimum by the cost of inflation. So if inflation averages 2% over 15 years, that's a 35% increase in your living expenses from just that. So your cost of living at retirement is 35% higher than today. Example numbers (not mine): If you predict your annual expenses to be $48k at today's rate and you want a 4% withdraw over retirement, you nominally want $1.2M in savings to sustain that.…