You supply the two CPI values — on purpose
This page embeds no price table. A hardcoded CPI list starts going out of date the day it is written: the Bureau of Labor Statistics publishes a new figure every month and revises seasonally adjusted series afterwards. Take both index values from the live series and you always compute against current, citable data — and you know exactly which vintage you used.
Look up CPI index values at BLS →The amount
Expressed in the starting period’s dollars.
Only needed to annualise the change.
The two CPI index values
The index value, not a percentage. Copy it from the BLS series.
Use the same series for both — do not mix seasonally adjusted with unadjusted.
Recorded in the worked solution so your citation stays with the arithmetic.
Equivalent amount
$130,000.00
$100,000.00 in the starting period has the same purchasing power as $130,000.00 in the ending period.
Cumulative price change
30.00%
Price ratio 1.3000
Average annual rate
2.658%
Compounded
Held as cash, worth
$76,923.08
In starting-period dollars
Read this alongside the answer
- CPI measures a national average basket. It is not a cost-of-living index for any individual household, and it is not the right deflator for every purpose — BLS publishes regional and item-level series, and BEA publishes the PCE price index used by the Federal Reserve.
Step-by-step solution for your numbers
Every figure below comes from the two index values you entered, so the calculation is reproducible from your own citation rather than from data hidden inside this page.
Step 1: Form the price ratio from the two index values
- Formula
- ratio = CPI_end ÷ CPI_start
- Your numbers
- 260.000 ÷ 200.000
- Result
- 1.300000
The ratio says how many the ending period dollars buy what one the starting period dollar bought.
Step 2: Multiply the amount by the ratio
- Formula
- adjusted = amount × ratio
- Your numbers
- $100,000.00 × 1.300000
- Result
- $130,000.00
$100,000.00 in the starting period has the same purchasing power as $130,000.00 in the ending period.
Step 3: Convert the ratio into a cumulative price change
- Formula
- cumulative = (ratio − 1) × 100
- Your numbers
- (1.300000 − 1) × 100
- Result
- 30.00%
Step 4: Annualise the change over the period
- Formula
- annual rate = ratio^(1/n) − 1
- Your numbers
- 1.300000^(1 ÷ 10.00) − 1
- Result
- 2.6584%
This is the constant yearly rate that compounds to the same cumulative change — the same operation as a CAGR.
Step 5: Restate the reverse direction: purchasing power held flat
- Formula
- start-dollar value = amount ÷ ratio
- Your numbers
- $100,000.00 ÷ 1.300000
- Result
- $76,923.08
Holding $100,000.00 in nominal dollars across this span leaves 23.08% less purchasing power than at the start.
The formula
adjusted = amount × (CPI_end / CPI_start)
cumulative = (CPI_end / CPI_start − 1) × 100
annual rate = (CPI_end / CPI_start)^(1/n) − 1
The price ratio does all the work: it says how many ending-period dollars buy what one starting-period dollar bought. Everything else on the page is that ratio expressed a different way.
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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