Getting the inputs right
Use the index value, not the inflation rate. CPI is published as an index level — a number in the hundreds — and the ratio between two levels is what converts dollars. Entering a percentage change in those fields produces a confident, meaningless answer.
Take both figures from the same series. Seasonally adjusted and unadjusted CPI values are both correct and are not interchangeable; mixing one of each introduces an error the arithmetic cannot see and the result will not reveal. The same applies to mixing a regional series with the national one.
Record which series and which periods you used. The reason this page asks for optional period labels is that they travel into the worked solution, so the calculation you paste into a document carries its own provenance instead of arriving as a bare number.
To turn an inflation-adjusted pair of endpoints into a real growth rate — the correct order of operations, rather than subtracting inflation from a nominal rate — use the CAGR calculator
Methodology and sources
The arithmetic here is the standard CPI ratio method used to restate dollar amounts across periods. What is deliberate is what the page does not contain: any CPI data. Both index values are inputs, sourced by you from the live BLS series and optionally labelled with their own periods.
That choice costs a little convenience and buys the thing that matters on a site whose promise is verification. An embedded price table cannot stay correct — BLS publishes monthly and revises seasonally adjusted series afterwards — so a copied table drifts silently while continuing to look authoritative. A calculator that quietly rots is worse than one that asks you for a citation, because only one of the two fails visibly.
All arithmetic runs in your browser; nothing you enter is transmitted or stored. The sources below link to the agency documents themselves, so you are always reading the current figure rather than a copy of it.
Primary sources
U.S. Bureau of Labor Statistics
Consumer Price Index — databases and seriesThe live CPI series. This is where both index values on this page should come from, and the reason this calculator embeds no price data of its own.
U.S. Bureau of Labor Statistics
Handbook of Methods — Consumer Price IndexThe authoritative description of how CPI is constructed: the basket, the weighting, the sampling design, and the revision policy that makes a copied table unreliable.
U.S. Bureau of Labor Statistics
CPI questions and answersThe agency’s own statement of what CPI does and does not measure — including, directly, that it is not a cost-of-living index for an individual household.
U.S. Bureau of Economic Analysis
Personal Consumption Expenditures Price IndexThe alternative price measure, broader in coverage than CPI and the one referenced by the Federal Reserve for its inflation objective.
Links go to the publishing agency, so you always read the current figure rather than a copy of it. This page embeds no agency data of its own.
Common questions
Why doesn’t this page just have the CPI values built in?
Because an embedded table starts aging the moment it is written. BLS publishes a new CPI figure every month and revises seasonally adjusted series afterwards, so a copied table quietly drifts out of date while still looking authoritative. Taking the two values from the live series means you always compute against current data — and you know precisely which vintage your answer rests on, which is what makes it citable.
Where do I find the CPI index value for a given month?
The BLS CPI databases publish the full CPI-U series by month and year. Use the index value itself, not the percentage change, and take both of your figures from the same series — mixing a seasonally adjusted value with an unadjusted one introduces an error that no formula can detect.
Which CPI series should I use?
For general-purpose adjustment of dollar amounts over time, CPI-U for All Urban Consumers, US city average, all items, is the standard choice and the one most published comparisons use. BLS also publishes regional series, item-level series, and CPI-W; the right one depends on what your amount represents.
Is CPI the same as my cost of living?
No. CPI tracks the price of a fixed national basket of goods and services for an average urban consumer. It is not a cost-of-living index for any particular household, and it does not reflect your spending pattern, your region, or the specific things you buy. It is the right tool for restating dollars across time, not for measuring what happened to any individual budget.
What if the index went down?
Then prices fell over that span, and the adjusted amount is correctly smaller than the original. That is deflation, not an input error, and the page flags it so the result is not mistaken for a mistake.
Should I use CPI or the PCE price index?
Both are legitimate and they differ in coverage and weighting. CPI, from BLS, is the most widely cited and the basis for most statutory adjustments. The PCE price index, from the Bureau of Economic Analysis, has broader coverage and is the measure the Federal Reserve refers to for its inflation objective. If your comparison is to a specific published figure, use whichever series that figure used.
Can I use this to compute a real growth rate?
Yes, and it is the right way round. Convert both endpoints into the same period’s dollars first, then compute the growth rate on the adjusted figures. Computing a nominal rate and then subtracting inflation is an approximation that drifts as rates rise.
This page does the arithmetic. We check the numbers you put into it.
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These calculators are provided for general business analysis and are independent informational research — not investment, financial, legal, or tax advice. The arithmetic is standard and openly documented on this page; the assumptions you enter are yours, and the conclusions drawn from them are too.