Inflation is the silent tax on your savings. A dollar saved today does not buy the same basket of goods ten or twenty years from now — and the gap grows faster than most people expect because prices compound, not just add. This inflation calculator takes an amount in today's dollars, an assumed annual inflation rate, and a number of years, then shows you what that same amount will cost in the future and how much purchasing power it loses along the way.
Slide the three inputs and every figure updates instantly. Test a calm 2% target, a hot 7% year, or a multi-decade retirement horizon to see just how much your future self will need.
How to Use
- Enter the Amount (Today's Value) — a price, salary, rent, or savings balance expressed in dollars as they are worth right now.
- Set the Annual Inflation Rate. The US Federal Reserve targets about 2%, while the long-run average measured by the Bureau of Labor Statistics (BLS) Consumer Price Index (CPI) has been closer to 3%. Run a stress test at 7% to see what a high-inflation decade does to your plan.
- Choose the Number of Years — how far ahead you want to look. A 10-year window shows medium-term erosion; a 20–30 year window is what matters for retirement planning.
- Read the result card. Future Cost tells you the price tag in future dollars. Purchasing Power of Today's Money tells you what your current amount will actually buy in that future year. Purchasing Power Lost is the gap — the value inflation quietly consumes.
The engine compounds the rate year by year using the same geometric growth model behind the official CPI index, rather than applying a simple one-time percentage.
The Inflation Formula
Inflation compounds exactly like interest, except that it erodes value instead of building it. The future cost of today's price is:
futureCost = P × (1 + r)ⁿ
Where:
- P is the present amount in today's dollars.
- r is the annual inflation rate as a decimal (3% becomes 0.03).
- n is the number of years.
Purchasing power moves the other direction, dividing instead of multiplying:
purchasingPower = P / (1 + r)ⁿ
Worked example: take $1,000 at a steady 3% over 10 years. The growth factor is 1.03¹⁰ = 1.3439, so the future cost of that $1,000 basket is $1,343.92. Meanwhile, the purchasing power of your original $1,000 shrinks to $744.09 — meaning you have lost about $255.91 of real value, a cumulative inflation of 34.39% over the decade. Notice that prices did not rise by a flat 30%; compounding pushed the cumulative increase to more than a third.
If the rate is 0%, the factor is exactly 1.0, so future cost equals today's amount and nothing is lost — the baseline of "no inflation."
Why It Matters for Savers and Retirees
Cash sitting in a low-interest savings account is the most exposed asset of all. At a 3% inflation rate, $100,000 held in mattress cash loses roughly $25,591 of real purchasing power over 10 years, even though the nominal balance still says $100,000. This is why financial advisors urge you to beat inflation, not just beat zero: a savings account paying 0.5% while prices rise 3% is a guaranteed loss in real terms.
Retirees drawing a fixed pension feel this sharply. A $50,000 annual pension at 3% inflation needs to grow to about $90,306 after 20 years just to maintain the same lifestyle, while its purchasing power falls to roughly $27,684. Cost-of-living adjustments (COLAs) are designed to track the BLS CPI precisely to close that gap.
Examples
Example 1 — Everyday goods. A grocery basket that costs $100 today runs at 7% annual inflation for 10 years. The future cost rises to $196.72, while $100 of today's money buys only about $50.83 of groceries — prices nearly doubled while the cash lost half its bite.
Example 2 — A savings stress test. Set the amount to $1,000,000, the rate to 3%, and the horizon to 10 years. To hold the same standard of living, that nest egg must grow to about $1,343,916 in nominal terms; otherwise its real purchasing power drops to roughly $744,094. This is the number that makes the difference between a conservative bond ladder and a diversified growth portfolio.
Example 3 — A salary negotiation. If your employer offers a 2% raise while inflation runs 5%, your real pay is shrinking. The calculator shows the hidden cut: a $75,000 salary at 5% inflation must reach about $94,688 after five years just to stay flat, before counting any actual raise.
FAQ
How do you calculate inflation over multiple years?
Inflation compounds geometrically. Use futureCost = P × (1 + r)ⁿ, where P is today's amount, r is the annual inflation rate as a decimal, and n is the number of years. Divide P by the same factor to find how much purchasing power the original amount retains in the future.
What is a good average inflation rate to assume?
The US Federal Reserve targets 2%, and the long-run CPI average measured by the Bureau of Labor Statistics is roughly 3%. For planning, use 3% as a baseline and run a stress case at 5–7% to see how exposed your savings are to a high-inflation period.
Why does compounding make inflation worse than a simple percentage?
Because each year's price increase is applied to an already-raised price. At 3% over 10 years, a simple rule of thumb says 30%, but compounding produces a cumulative inflation of about 34.39%. Over 20 years the gap widens further — roughly 80% cumulative instead of a flat 60%.
What will $100 be worth in 10 years?
At 3% annual inflation, $100 today will have the purchasing power of about $74.41 ten years from now, and a basket that costs $100 today will cost about $134.39. At 7%, that same $100 buys only about $50.83 of future goods.
How do I use this for retirement planning?
Project your expected annual spending in today's dollars, then inflate it by your chosen rate over the years until retirement. The result tells you the nominal income you will need. Compare it to your projected Social Security, pension, and portfolio withdrawals to see whether you have a shortfall.
Does this calculator use the official CPI?
The method mirrors the geometric growth model behind the BLS Consumer Price Index, and the reference rate should be drawn from the latest published CPI figures at bls.gov/cpi. Your own assumed rate is a planning estimate, not a forecast — past inflation never repeats itself exactly.
What is the difference between future cost and purchasing power?
Future cost is the price tag expressed in future dollars — what you will hand over at the register. Purchasing power is what your current dollars will actually buy in that future year. As future cost rises, purchasing power falls; the lost value between them is the real cost of inflation.
Disclaimer
This inflation calculator is provided for informational purposes only and does not constitute financial, investment, tax, or legal advice. Projections are based on the inflation rate and number of years you enter; actual inflation is measured by the Bureau of Labor Statistics CPI and varies by year, region, and spending category. Historical averages are not guarantees of future results. Always consult a qualified financial professional before making long-term saving, retirement, or investment decisions.