Estimated CPI Observations
finPack distinguishes between CPI observations published by the data provider and observations that were not published but have been approximated by finPack using a methodology published by the provider.
What estimated means in finPack
In finPack, an estimated observation is:
An observation not published by the provider and approximated by finPack using a methodology published by the provider.
Estimated observations are explicitly identified so that users can distinguish them from observations published directly by the provider.
An estimated finPack observation should not be interpreted as an official CPI observation published by the provider.
Approximating a missing BLS observation
For a missing U.S. BLS CPI observation, finPack can approximate the missing value using the geometric mean of the immediately preceding and following CPI observations:
Estimated CPI = √(Previous CPI × Following CPI)
The approximated value is rounded using the precision configured for the CPI series.
The U.S. Bureau of Labor Statistics describes this geometric-mean approach for approximating an unpublished CPI observation and notes that the resulting value is not an official CPI observation.
See BLS: Approximating missing data points.
How estimated observations are displayed
When an individual CPI value is estimated, finPack adds an estimated indicator next to the value.
For example:
Value 324.461 (estimated)
Published observations do not display an estimated indicator.
For example:
Value 170.0
Calculations that include estimated data
A calculation can use more than one CPI observation.
When one or more observations used in a calculation are estimated, finPack identifies the result as includes estimated.
For example:
Change from last month -0.1% (includes estimated)
or:
Increase 3.2% (includes estimated)
The phrase includes estimated means that at least one observation used in the calculation is estimated.
It does not mean that the complete calculation was estimated independently.
Estimated observations in CPI history
When a complete CPI series is inserted into Excel, the table includes an Estimated column.
This lets you identify estimated observations directly in the historical data.
For example:
| Year | Month | Date | Value | Estimated |
|---|---|---|---|---|
| 2025 | 10 | 2025-10 | 324.461 | Yes |
| 2025 | 9 | 2025-09 | 324.8 | No |
The CPI value remains numeric whether or not the observation is estimated.
Estimated observations in worksheet functions
finPack worksheet functions return numeric results.
For example:
=FINPACK.CPI("us","all-items",2025,10)
returns the numeric CPI value available to finPack for that period.
The worksheet result itself does not append text such as:
(estimated)
This keeps the result numeric so it can continue to participate in Excel calculations.
When estimated-data status is important to your analysis, review the corresponding CPI information in the finPack task pane or inserted CPI history.
Why an observation may be unavailable
A CPI provider may occasionally be unable to publish an observation for a particular reference period.
For example, the U.S. Bureau of Labor Statistics reported that CPI survey data could not be collected for October 2025 because of the 2025 lapse in federal appropriations.
For more information, see the BLS explanation of the 2025 federal government shutdown impact on CPI.
Using estimated data
Whether an estimated CPI observation is appropriate for a particular workbook or analysis depends on how the CPI information will be used.
finPack identifies estimated observations so that you can make that decision with the estimated-data status visible.
For work that requires provider-published observations only, review the Estimated status before using the affected value or calculation.
Related topics
- Countries and Series — Learn how finPack organizes CPI datasets.
- Data Sources — Review the statistical providers behind finPack data.
- CPI Value — See how estimated observations are displayed in the task pane.
- CPI Average Change — See how calculations identify results that include estimated observations.