Inflation Planning
Published on September 19, 2025. Updated on August 2, 2026.
To find what a sum will be worth in future buying power, divide it by (1 + inflation rate) raised to the number of years. At 3% inflation, $100,000 held for 20 years still says $100,000 but buys what $55,367 buys today. Looked at the other way, something costing $100,000 now would cost $180,611 in 20 years.
Published by PraxisCalc, a Zeta Digilux Labs project
Inflation reduces purchasing power over time. That matters for retirement corpus planning, education costs, household budgets, and any goal where today's price will not be enough in the future.
To calculate a future cost with inflation, multiply today's cost by one plus the inflation rate raised to the number of years.
Future Cost = Current Cost x (1 + Inflation Rate)^Years
Example: $50,000 at 3% annual inflation for 20 years becomes about $90,306. The inflation premium is about $40,306, which is the extra amount needed to keep the same purchasing power.
Retirement planning often fails when today's expenses are used without inflation. If monthly expenses are $4,000 today and inflation averages 4% for 25 years, the same lifestyle may cost about $10,663 per month later. That higher future expense increases the retirement corpus needed.
For retirement-specific planning, use the Retirement Corpus Calculator. For general price changes, use the Inflation Calculator.
Use the inflation calculator to compare today's price with a future inflation-adjusted estimate.
Use the Inflation Calculator →The inflation premium is the extra future amount needed because prices rise. If today's cost is $50,000 and the future cost is $90,306, the inflation premium is $40,306. This idea is useful when estimating tuition, retirement expenses, insurance coverage, and long-term savings goals.
Nominal return is the return before inflation. Real return is the return after inflation. If an investment earns 7% while inflation is 3%, the simplified real return is about 4%. Long-term plans should aim for returns that beat inflation after fees and taxes.
At 3% inflation, $100,000 will have the buying power of about $55,367 in today's money. The formula is $100,000 / (1.03)^20. At 4% inflation it falls further, to roughly $45,639.
To find future buying power: PV = FV / (1 + i)^n. To find what something will cost later: FV = PV x (1 + i)^n. Both use the same annual inflation rate i and number of years n.
About $41,199 in today's buying power at 3% inflation. The erosion compounds, so the third decade costs you more purchasing power than the first even at an unchanged rate.
Multiply today's price by (1 + inflation)^years. A $50,000 car costs about $90,306 in 20 years at 3%, and a $400,000 house about $722,444, assuming those categories track general inflation.
Many central banks target around 2%, and long-run realised inflation in developed economies has often run closer to 3%. Running your plan at both, and again at 4%, shows how sensitive the answer is to an assumption nobody can pin down.
It means cash held for decades loses real value, not that saving is pointless. The comparison that matters is your return against inflation. A 5% return during 3% inflation grows real wealth at roughly 2% a year; a 1% savings account during 3% inflation shrinks it.
Nominal return is the percentage gain an investment shows before adjusting for inflation, while real return subtracts out inflation's effect to show how much your purchasing power actually grew. A 6% nominal return during a year of 4% inflation produces a real return of roughly 2%, meaning your money's ability to buy goods and services grew by only about 2%, not 6%. This distinction matters most for long-term goals like retirement, where nominal-looking growth over decades can mask a much smaller gain in actual purchasing power once inflation over that period is properly accounted for.
Money held in cash or a low-yield account loses purchasing power every year that inflation exceeds the interest earned, and this erosion compounds the same way growth does, just in the opposite direction. Anyone relying on a fixed monthly payment, such as a pension without a cost-of-living adjustment or a fixed annuity payout, sees that payment buy noticeably less with each passing year of inflation, even though the dollar amount received never changes. This is a central reason retirement planning models typically build in an inflation assumption for future expenses rather than assuming today's cost of living will hold steady for a 20-30 year retirement.
Equities, real estate, and inflation-protected government securities have historically tended to outpace inflation over long holding periods better than cash or fixed-rate bonds, since company revenues, rents, and adjusted bond principal can rise along with general price levels. This isn't a guarantee for any specific short period, since these assets can also lose value or lag inflation in individual years, but over multi-decade horizons they've generally provided better real (inflation-adjusted) returns than holding cash. This is one of the practical reasons long-term retirement savings are typically invested rather than left in cash: cash preserves nominal value but reliably loses real value to inflation over time.
Inflation is not just a background statistic. It changes the future cost of retirement, education, housing, and everyday spending. Use inflation-adjusted estimates whenever a financial goal is years away. For official guidance on this topic, see the Bureau of Labor Statistics' Consumer Price Index.
Compare Systematic Investment Plans (SIP) against one-time lump sum investments.
Learn how annuities work and their role in a long-term financial plan.