Inflation Calculator: Today's Money vs. Future Purchasing Power

Why inflation matters for every long term plan

Any financial decision that involves a future date has an inflation problem hidden inside it. The retirement number you read in a magazine is in today's dollars, even if you are 30 years away from retiring. The college savings goal you set assumes today's tuition. The income you think you will earn in your peak years is quoted in current pay scales.

The correction is not complicated, but it has to happen. Take any future dollar goal, plug it into this calculator at the inflation rate you find defensible, and see what you actually need in inflation adjusted future dollars. A million dollars of retirement savings at age 65 sounded like a fortune to people retiring in the 1990s, and it still sounds substantial, but a million dollars 30 years from now will buy roughly what $400,000 buys today.

The two ways to think about inflation

The first way is the discount view. You have a future amount and you want to know its real value in today's purchasing power. Useful when you receive a quote for a future payment, like a pension promise, an annuity, or a long deferred bonus. Run the future amount through the calculator backwards to see what it is worth today.

The second way is the target view. You know what you need to be able to buy in the future, in today's terms, and you want to know what nominal dollar figure that translates to. Useful when planning retirement, college costs, or any savings goal that will be spent decades from now. The calculator shows this as the inflated target line.

Choosing an inflation rate that holds up

US CPI has averaged about 3 percent annually over the past 30 years. Over the past 50 years it has averaged closer to 4 percent because the late 1970s and early 1980s saw double digit inflation. For very long horizons, 3 percent remains the most common planning assumption.

Recent experience matters too. From 2021 to 2023, US inflation peaked at over 9 percent and stayed elevated. If you believe the current decade will average higher than the long run, use 4 percent. If you believe the recent surge was a transitory shock, 3 percent is still fine. The calculator lets you test both.

For short term decisions like a one year contract or a five year savings goal, use a near term forecast. Federal Reserve projections and bond market breakeven inflation rates are reasonable references. For long term decisions like retirement, do not anchor too heavily on this year's rate. Use a long run number.

Real versus nominal returns

The most important way inflation enters investment math is the distinction between real and nominal returns. Nominal return is the headline percentage your account earned. Real return is what you actually gained in purchasing power, equal to the nominal return minus inflation.

If your portfolio returned 8 percent and inflation was 3 percent, your real return is roughly 5 percent. That is the number that compounds your actual buying power. Long term, real returns for US stocks have been around 7 percent, real returns for bonds 1 to 3 percent, and real returns on cash near zero.

This calculator lets you stress test the real value of a future balance. Run the compound interest calculator to see your projected nominal balance, then run this calculator on that balance to see what it is worth in today's purchasing power.

Currencies with different inflation profiles

The default 3 percent rate is appropriate for the US dollar and similar developed market currencies. If you are projecting in a different currency, use that country's long run CPI as a baseline. Emerging market currencies often see meaningfully higher inflation. The historical Brazilian real, Turkish lira, or Argentine peso have inflation profiles that make a 3 percent assumption deeply wrong.

When you hold savings in a high inflation currency, the math of inflation can dominate any reasonable return rate. This is one reason why people in high inflation economies often convert savings into a stable currency or into hard assets. The calculator helps quantify how big that effect is over a given horizon.