Yes, it changes the math — Coast FIRE is calculated backward from your eventual spending target, and moving somewhere your spending drops by a third pulls that target down by roughly the same amount. What it doesn't change is the part people skip: whether the lower cost of living is a real, sustained number or a guess based on a vacation.
The mechanics, quickly
Coast FIRE is the portfolio size at which, if you stopped contributing today, compound growth alone would carry it to your full retirement number by a traditional retirement age. Hit that number, and you can stop saving — cover current expenses from current income, let the existing portfolio do the rest silently in the background.
Barista FIRE is a step further into actual early retirement: part-time or lower-stress work covers some of your living costs, and a smaller portfolio than full FIRE would require covers the remainder. Both are the same underlying formula — future spending target, divided by a safe withdrawal rate, discounted back to today's portfolio requirement — just landing on different combinations of "how much is covered by work" and "how much is covered by the portfolio."
A worked example
Someone targeting $50,000 a year in retirement, at a 4% withdrawal rate, needs a $1.25 million portfolio. Move that same lifestyle somewhere spending drops to $32,000 a year — not unrealistic for several popular retirement destinations — and the target portfolio drops to $800,000. That's the geoarbitrage effect on Coast FIRE, direct and real: less needed, sooner reachable.
What doesn't show up in a cost-of-living index
Four things routinely eat into the savings a lower cost of living promises. Currency risk, first — a multi-decade retirement drawing income in one currency while spending in another means exchange rate movement is a real, uncontrolled variable, not a rounding error. Healthcare, second — cost and quality vary enormously by country, and what looks like a savings line item can turn into a genuine gap in coverage. Visa renewal requirements, third — rules change, and a plan built around a visa category that gets tightened is a plan that needs a backup. And the actual cost of staying connected to home — flights, visits, the version of "cheap" that assumes you never fly back — which a Numbeo cost index doesn't price in at all.
None of these make geoarbitrage a bad idea. They make "just move somewhere cheaper" an incomplete plan without the specific numbers behind it.
Where the real numbers live
The 2021 vs 2026 cost-of-living comparison tracks Numbeo index data across a dozen-plus popular retirement destinations — several of which moved by 20% or more in just five years, in both directions. That's the input a Coast FIRE recalculation actually needs, not a guess.
Run your actual Coast FIRE number, two ways
Set a domestic income target as Scenario A, a lower geoarbitrage target as Scenario B, and see the portfolio-size gap directly.
✦ Open the FIRE Abroad Calculator — it's free