CPI Inflation Calculator

The formula behind the calculator

The consumer price index (CPI-U) tracks what a fixed basket of goods and services costs an average US urban household. The US Bureau of Labor Statistics publishes it every month, and annual averages run from 1913 to today. Two index values are all you need to translate money across time: the CPI in the earlier year and the CPI in the later year.

The translation formula is:

Cost_later = Cost_earlier x (CPI_later / CPI_earlier)

And the cumulative inflation between the two years is:

Inflation % = ((CPI_later - CPI_earlier) / CPI_earlier) x 100

Both come straight from the index itself, so any answer the calculator gives can be checked by hand in one step. The index is built so that 1982-84 averages 100, which is why the raw numbers look small for old years: the 1913 index sits at 9.9, while 2025 sits at 321.9.

The series itself comes from the US Bureau of Labor Statistics CPI program, and FRED hosts the annual series as CPIAUCSL for anyone who wants the raw data behind a calculation.

What a dollar from each decade is worth in 2025

Each row divides 321.9 by that year's index and multiplies by 100. The further back you start, the harder the arithmetic bites: a 1970 dollar carries more than eight times its face value in 2025 terms, while a 2020 dollar has already lost about a fifth of its buying power in five years.

Reading the table by rows also shows the compounding asymmetry: between 1950 and 1970 the index moved from 24.1 to 38.8, a 61% rise, but between 1970 and 1990 it moved from 38.8 to 130.7, a 237% rise. Someone who kept a dollar under a mattress from 1950 lost far more purchasing power in the second twenty years than the first, even though the two spans look symmetric on a calendar.

Worked example: $100 in 1990 to 2025

Take the headline example: $100 in 1990. The annual average CPI-U was 130.7 in 1990 and 321.9 in 2025.

Step 1: ratio = 321.9 / 130.7 = 2.4629

Step 2: Cost_2025 = 100 x 2.4629 = $246.29

Step 3: cumulative inflation = ((321.9 - 130.7) / 130.7) x 100 = 146.3%

So the same shopping cart that cost $100 in 1990 costs $246.29 in 2025, and prices overall rose 146.3% across those 35 years. Divided out, that is an average of 2.61% per year: (2.4629)^(1/35) - 1 = 0.0261.

Worked example: the salary that fell behind

Wages work the same way. Suppose a job paid $50,000 in 2015 and still pays $50,000 in 2025. The CPI-U was 237.0 in 2015 and 321.9 in 2025.

Step 1: ratio = 321.9 / 237.0 = 1.3582

Step 2: needed salary = 50,000 x 1.3582 = $67,911

Step 3: shortfall = 67,911 - 50,000 = $17,911, a 35.8% pay cut in real terms

A nominal raise from $50,000 to $55,000 over the same span still falls short: 55,000 / 1.3582 = $40,494 in 2015 dollars, which is $9,506 below the 2015 pay. This is the calculation union negotiators and HR teams run every contract cycle.

Three ways to quote the same result

Two index values produce one ratio, and the same ratio supports three different sentences: the equivalent amount, the cumulative inflation percentage, and the average annual rate. The calculator shows all three so the answer can be quoted in whichever form the conversation needs.

The override box handles a case the table cannot: a partial-year index. BLS publishes mid-year readings, and anyone comparing against a monthly figure can type it in as the end index instead of waiting for the annual average to be finalized.

A caution on the annual rate line: it is a geometric mean, not an arithmetic one. Cumulative inflation of 146.3% over 35 years divided by 35 gives 4.2% per year, but that overstates the compounding reality. The correct figure is (2.4629)^(1/35) - 1 = 2.61%. The calculator always reports the geometric figure, which is the one that matches what compound-interest math would need.

How the index has moved by period

The BLS updates the CPI-U monthly, and each year's annual average is final once the year closes. The figures in this tool run from 1913 through 2025. Over long spans the annual average is the right series to use because it smooths month-to-month noise: energy shocks and sales cycles wash out.

The 1970s stand out as the worst decade in the modern record, with prices more than doubling. The 1990s and 2000s ran near 2.5% a year, close to the Federal Reserve's informal 2% target.

One more reading helps: the ratio between adjacent-year index values gives that year's headline inflation. From 2021 (271.0) to 2022 (292.7) the ratio is 1.0801, the familiar 8.0% print. The same one-line division, applied one year apart instead of decades apart, reproduces every monthly news headline.

What the CPI-U does not capture

The CPI-U has known limits, and anyone quoting a result should know which ones apply.

Where an inflation adjustment belongs

Four uses cover most of what people bring to an inflation calculator:

• Salary reviews and offers: convert an old salary to current dollars before judging whether a raise is real. A 3% raise in a 4% inflation year is a pay cut in purchasing power.
• Rent and lease reviews: many commercial leases index rent to CPI. Both sides can check the arithmetic with two index values.
• Family history and genealogy: what did a 1955 house price of $12,000 mean? $12,000 x (321.9 / 24.1) = $160,282 in 2025 dollars.
• Contract clauses and alimony: agreements that reference "the CPI" need a defined series. CPI-U, annual average, is the most common choice.

For future projections, a different tool applies: expected inflation and compound growth need assumptions about rates yet to happen, not published index values.

For the official series and methodology papers, start with BLS CPI and the tax-side application in the IRS annual inflation adjustments.