“I will wait — the rate looks bad this week.” That is the sentence that comes up most when I sit down with someone who earns in dollars and owes in reais, and it is almost always said without any arithmetic behind it.
So let us put the arithmetic behind it. Not to find the right week — nobody at my desk knows where the Brazilian real goes next — but to price exactly what waiting is worth and what it costs.
Every rate below is an invented example, chosen to show the shape of the calculation. Look up the live rate before you act — the Banco Central publishes official exchange rates, and the current IOF percentage comes from an official source, never from an article. Then redo the tables with your own figures.
What six months of conversions actually averages
Say your obligations in Brazil come to R$3,200 a month. Here are six example months, and two ordinary rules run side by side: convert the R$3,200 you need, or convert a fixed US$640.
| Month | Example rate (R$ per US$1) | Rule A: buy R$3,200 | Rule B: sell US$640 |
|---|---|---|---|
| 1 | 5.20 | US$615.38 | R$3,328 |
| 2 | 5.05 | US$633.66 | R$3,232 |
| 3 | 4.90 | US$653.06 | R$3,136 |
| 4 | 5.35 | US$598.13 | R$3,424 |
| 5 | 5.15 | US$621.36 | R$3,296 |
| 6 | 4.95 | US$646.46 | R$3,168 |
| Total | average 5.10 | US$3,768.05 for R$19,200 | R$19,584 for US$3,840 |
| Effective rate achieved | — | R$5.096 | R$5.100 |
Both rules land on the average of the six months, because that is arithmetically what they are built to do. Put the same US$3,840 through Rule A’s effective rate and you get R$19,567 against R$19,584 — a difference of about R$16, under a tenth of one percent.
Now price the timing game against that. The best month was 5.35 and the worst was 4.90, a range of roughly 9%.
- All US$3,840 converted in month 4: R$20,544 — R$960 better, about +4.9%.
- All US$3,840 converted in month 3: R$18,816 — R$768 worse, about −3.9%.
- Spread across all six months by rule: R$19,584.
So perfect timing was worth R$960 over six months, and bad timing cost R$768. You are being asked to make one call, months in advance, on a coin with those two faces — and to make it again every six months for the rest of your working life.
A rule wins because it removes the input you cannot supply, which is the date. This is the same reasoning that sits underneath how currency risk works when your income and your bills are in different currencies: you are not trying to beat the rate, you are trying to stop one date from deciding your year.
The three rules that survive contact with a paycheck
Three versions actually hold up, and all three work by fixing something other than the rate. Pick one and write it down — an unwritten rule is a mood.
1. A fixed date
The same day each month, whatever the screen says. Twelve prices a year instead of one, and no decision to make on the day. It is the weakest rule intellectually and the easiest to actually follow, which usually makes it the best one.
2. A fixed share of income
A set percentage of each paycheck becomes reais. If you earn US$5,000 and send 20%, that is US$1,000 a month regardless of the quote. This rule scales with a raise, and it suits someone building a balance in Brazil rather than covering a fixed bill. What it does not do is size itself to your actual bills, so it can overshoot or undershoot for months at a time.
3. Convert against known expenses
The strongest of the three. List what you owe in reais over the next twelve months and convert exactly that, when it is due.
R$3,200 a month of running costs, plus R$1,800 of property tax in January, plus R$2,400 of school fees in February, is R$42,600 for the year. At an example R$5.00 that is US$8,520. Now you are hedging an obligation instead of holding a view — which is what a natural hedge means once the jargon is gone.
Frequency costs more than timing
Here is the part almost nobody prices. Every conversion is a priced FX operation, and part of that price is flat, so how often you convert is a fee decision before it is a rate decision.
Take the R$38,400 of annual running costs. Assume, as an example only, a flat R$75 per transfer — a US$10 sending fee at R$5.00, plus a R$25 receiving fee — and an example proportional cost of 3.5% covering the exchange rate spread and IOF, the federal tax on foreign exchange operations.
| Conversions per year | Flat cost | Proportional cost (example 3.5%) | Total | As % of R$38,400 |
|---|---|---|---|---|
| 12 (monthly) | R$900 | R$1,344 | R$2,244 | 5.84% |
| 4 (quarterly) | R$300 | R$1,344 | R$1,644 | 4.28% |
| 2 (twice a year) | R$150 | R$1,344 | R$1,494 | 3.89% |
Moving from monthly to quarterly saved R$600 a year, or 1.56% of everything sent. That saving is certain. The 4.9% prize in the timing table was a maybe that required knowing the future.
The trade-off is real, though: four prices a year instead of twelve, and three months of reais sitting in Brazil. Idle reais are a second cost, which is why what happens between conversions belongs to what Brazil’s interest rate is actually worth to someone earning abroad. Nothing here is a recommendation to buy any particular product — this is mechanism, not personalized investment advice, and what fits you depends on facts a post cannot know.
Before you fix a frequency, measure your own flat cost per transfer. The method is in the full line-by-line cost of sending money into Brazil, and it takes one old confirmation and ten minutes.
The one case where waiting is defensible
There is exactly one, and it has nothing to do with the rate looking good or bad.
Waiting is defensible when you have nothing in reais for the money to do. No obligation in Brazil in the window, a buffer in reais already funded, no plan to move. Converting then does not close an exposure — it opens one, because you would be taking on currency risk you have no bill to justify.
That is not timing. That is declining to open a position you have no use for, and the honest version of the sentence is “I have no reais obligation this quarter”, not “the rate is bad”.
The mirror case runs the other way. If you are returning to Brazil in three months and the deposit, the movers and the first rent will all be paid in reais, those obligations already exist and waiting is the position, not the safe choice. Money you will need in reais on a known date is the clearest argument for converting on a schedule you control.
One thing I will not do here is tell you what any of this means for what you owe or declare. Whether a conversion or a transfer has to appear anywhere is a question for a contador, a Brazilian accountant, and one paid hour is cheaper than a year of guessing.
Do this before your next payday
Write down three numbers, in this order.
- Your real obligation in reais, monthly, from actual bills rather than an estimate — the number the whole plan is sized against.
- Your flat cost per transfer, rebuilt from your last confirmation.
- The frequency where that flat cost stops being noticeable against the table above.
Then put the date in next month’s calendar and convert on it without opening a rate chart first. The rule is the product; the rate is the weather. The wider map of the decisions this one sits inside is in the guide to earning abroad when your money and family are in Brazil.