What your money will actually buy later
What your money will actually buy later
Inflation is the rate at which prices rise, which is the same as saying it is the rate at which each unit of currency buys less. Enter an amount, an assumed inflation rate, and a number of years to see what that sum will be worth in today's purchasing power, and what you would need in future dollars to match it.
The effect is quiet and cumulative, which is why it is so easily underestimated. A rate of 3% sounds trivial in any single year. Over decades it is one of the largest forces acting on your finances.
Future purchasing power of a fixed sum:
Real value = Amount ÷ (1 + i)n
And the amount needed later to match today's buying power is the same relationship reversed: Amount × (1 + i)n.
Worked example: $50,000 at 3% inflation over 20 years retains the purchasing power of about $27,684 in today's terms. To buy in 20 years what $50,000 buys now, you would need roughly $90,306. Nearly half the value of idle cash disappears across a normal working lifetime.
Dividing 72 by the inflation rate gives roughly the number of years for prices to double. At 3%, that is 24 years. At 6%, just 12. Turned around, it is also how long it takes for money under a mattress to lose half its value.
This is the clearest argument against holding large sums in cash indefinitely. A savings account paying 0.5% during 3% inflation is losing 2.5% of real value annually — a guaranteed loss that never appears on a statement, because the nominal balance only ever goes up.
The number that actually matters is the real return: what you earned after inflation.
Real return ≈ Nominal return − Inflation
A 7% investment return during 3% inflation is a real return of about 4%. A 5% savings rate during 6% inflation is a real return of −1% — you are getting poorer while your balance grows. Any discussion of returns that omits inflation is incomplete.
This is also why long-horizon money is usually invested rather than saved. Over thirty years, the gap between a 4% real return and a −2% real return is not a matter of optimisation; it is the difference between reaching a goal and not.
One place inflation helps you: fixed-rate debt. If you owe $300,000 on a 30-year fixed mortgage, inflation erodes the real value of those future payments while your obligation stays nominally fixed. You repay with money that is worth less than the money you borrowed.
This does not apply to variable-rate debt, where rates typically rise alongside inflation, nor to credit card balances at rates far above any plausible inflation figure. But it is a genuine reason why aggressively overpaying a low fixed-rate mortgage during an inflationary period is less obviously optimal than it appears.
Three practical implications. First, retirement targets must be stated in future dollars — a figure that sounds comfortable today will not be in thirty years. Second, income needs to keep pace; a salary without an inflation-matching raise is a real-terms pay cut. Third, long-term savings held entirely in cash will not reach long-term goals, regardless of how disciplined the saving is.
Historically, broad stock market returns have outpaced inflation over long periods, which is the underlying reason long-horizon money is generally invested. That comes with volatility and no guarantees, and it is a poor fit for money needed soon. Matching the time horizon to the vehicle is the whole discipline.
Many central banks target around 2% annually as a stable long-run rate. Actual inflation varies considerably year to year, and has been both far higher and occasionally negative during different periods.
If your savings rate is below the inflation rate, you are losing purchasing power even though the balance grows. A 1% account during 3% inflation loses roughly 2% of real value each year.
It benefits holders of fixed-rate debt, since future repayments are made with money worth less than what was borrowed. It harms savers holding cash and anyone on a fixed income that does not adjust.
Historically, assets that grow over time - broadly diversified investments, and property in some markets - have outpaced inflation over long horizons. Inflation-linked government bonds adjust directly. Cash held long term does not keep pace.