Inflation Calculator

Inflation quietly erodes the value of money — a dollar today buys more than a dollar will in ten years. This inflation calculator shows both sides of that: how much a purchase costing a certain amount today will cost in the future, and how much buying power your cash will have lost if it just sits there. Understanding this is essential for retirement planning, long-term saving, and seeing why money needs to grow just to stand still.

How inflation affects money

Inflation is the general rise in prices over time, which means each dollar buys a little less each year. There are two useful ways to look at it. Looking forward, something that costs $100 today will cost more in the future at the same inflation rate. Looking at buying power, $100 of cash kept under the mattress will buy less in the future — its real value shrinks even though the number on the bill stays the same. This calculator shows both.

The formula

Future cost is Amount × (1 + rate)^years — the same compounding math as interest, working against you. The future buying power of today’s cash is the reverse: Amount ÷ (1 + rate)^years. The difference between your original amount and that reduced buying power is the value quietly lost to inflation.

A worked example

Assume 3% average inflation over 20 years. Something costing $10,000 today would cost about $18,060 then. And $10,000 in cash today would have the buying power of only about $5,540 in 20 years — meaning roughly $4,460 of real value simply evaporates if the money earns nothing. That’s nearly half. It’s a stark illustration of why leaving large sums in a no-interest account is itself a risk.

Using it for planning

Inflation is a key input in any long-term plan. A retirement target that looks comfortable today may fall short in 30 years of rising prices, which is why future-cost thinking matters. Pair this with our compound interest calculator to check whether your expected returns outpace inflation, and our retirement calculator for the bigger picture. As a reference, long-run US inflation has averaged roughly 3% a year, though it varies year to year.

Frequently asked questions

How does inflation affect the value of money?

Inflation raises prices over time, so each dollar buys less. Looking forward, the same goods cost more in the future; looking at buying power, cash held without growth loses real value. The calculator shows both the future cost of today's prices and the shrinking buying power of cash.

How do I calculate the future cost with inflation?

Multiply the amount by (1 + inflation rate)^years — the same compounding math as interest. At 3% over 20 years, $10,000 of goods would cost about $18,060. The buying power of $10,000 in cash would fall to roughly $5,540 over the same period.

Why does inflation mean I should invest?

Because cash that earns nothing loses real value every year to inflation. To preserve and grow wealth, your money generally needs to earn at least the inflation rate, ideally more. That's a core reason people invest for the long term — to avoid quietly getting poorer by holding cash.

What inflation rate should I use?

Long-run US inflation has averaged roughly 3% a year, though it varies and some years are much higher or lower. For long-term planning, a figure around 2–3% is a common assumption. Adjust it to be more conservative if you prefer. This calculator is for educational estimates only.