New to the 4% rule and FIRE numbers? Start with the FIRE Calculator and the Safe Withdrawal Rate Calculator, then come back here for the cross-currency version.
Currency-Aware FIRE Calculator#
Use your blended effective rate, not your top marginal rate. Entering the marginal rate overstates the tax and inflates the target. 0% for UAE/GCC residents; often 10-20% effective elsewhere, and lower still if most of a withdrawal is return of capital.
How your earn currency moves against your spend currency each year. Left = your earn currency weakens (you need more); right = it strengthens (you need less). We default to flat because no one reliably forecasts currencies. Set a weakening drift to stress-test the risk, not to lower your target.
Investable assets, in your retirement country's money, if you stopped working today.
Future earn currency units you must accumulate. This is a nominal figure, not today's money, so it will look larger than your current salary.
| Scenario | You need (earn) |
|---|
Note: inflation and FX drift are set independently here. Over long periods they tend to partly cancel, because a currency with higher inflation usually weakens over time. If you enter high spend-country inflation and also assume your earn currency weakens a lot, you may be counting some of the same effect twice. This is a deterministic planning estimate: it assumes steady returns, inflation, and FX, and does not model market crashes, sequence-of-returns risk, or the odds your money runs out. Treat the drift row as a range of outcomes, not a forecast.
Why a Normal FIRE Calculator Is Not Enough for Expats#
A FIRE number is a spending number. The standard rule is that you need about 25 times your annual expenses invested, so a 4% withdrawal covers your life. That works cleanly when you earn and spend in the same money.
The moment you earn in one currency and plan to retire in another, two things a normal calculator ignores start to matter:
- Your expenses are in the retirement country's currency. If you will live in the Philippines, your grocery bills, rent, and healthcare are in pesos, not dollars. The honest FIRE number is priced in pesos first.
- The exchange rate will move before you get there. You are saving in one currency today and will convert it into another over a working life. That drift is a real risk, and it only points one way that hurts you.
A Worked Example#
Say you earn and save in US dollars and plan to retire in the Philippines. You expect to spend about 1,200,000 pesos a year, you use the 4% rule, and you are 15 years out. Inflation in the Philippines runs around 3%.
- In pesos, your FIRE number today is about 30,000,000 (1,200,000 divided by 4%).
- Grown for 15 years of 3% inflation, that is roughly 46,700,000 pesos by your retirement date.
- At today's exchange rate that is about 758,000 US dollars.
Now the currency part. If the dollar weakens by 2% a year against the peso, each dollar you saved buys fewer pesos, so you need more dollars: closer to 1,030,000. If instead the dollar strengthens, you need less. A weakening earn currency is the risk, because it means your savings shrink in the money you will actually spend. That single assumption can move your target by hundreds of thousands, which is exactly why it deserves its own slider.
How to Read Your Results#
| Result | What it means |
|---|---|
| FIRE number today (spend currency) | What you would need right now, priced where you will live |
| FIRE number at retirement (spend currency) | The same target grown for inflation in your retirement country |
| FIRE number at retirement (earn currency) | The nominal amount to accumulate in the money you save, at your retirement date |
| Drift scenarios | How that earn-currency target changes if your currency weakens, stays flat, or strengthens |
This is an estimate for planning, not advice. It assumes a constant withdrawal rate, steady inflation, and a steady FX drift. Real currencies move in jumps, not straight lines, so treat the drift row as a range of outcomes, not a prediction.
Related Calculators#
More tools for globally mobile investors:
- FIRE Calculator - the single-currency starting point
- Safe Withdrawal Rate Calculator - stress-test your withdrawal rate against history
- Savings Rate Calculator - the biggest lever on how fast you get there
Go deeper: The 4% Rule Doesn't Speak Your Currency - why retiring into a currency you never earned in adds a second layer of sequence-of-returns risk.
