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FINPACK.CPIINCREASE

FINPACK.CPIINCREASE returns the CPI percentage change from the same month one year earlier.

This is the conventional 12-month CPI change commonly used to describe how CPI has changed over the previous year.

Syntax​

=FINPACK.CPIINCREASE(country, series, year, month)

Arguments​

ArgumentDescription
countryCountry code for the CPI data. For example, "ca" for Canada or "us" for the United States.
seriesCPI series identifier. For example, "all-items".
yearEnding year of the 12-month comparison.
monthMonth number from 1 through 12. The same month is used for both years.

Text arguments must be enclosed in quotation marks when entered directly in a formula.

How the calculation works​

FINPACK.CPIINCREASE compares the CPI for the requested month with the CPI for the same month one year earlier.

For September 2026, the comparison is:

September 2026
compared with
September 2025

Conceptually:

CPI for September 2026
────────────────────── - 1
CPI for September 2025

The calculation is equivalent to:

(Current CPI / Prior-year CPI) - 1

The result is rounded to one decimal percentage point.

Example​

To calculate the Canadian All-Items CPI increase for September 2026:

=FINPACK.CPIINCREASE("ca","all-items",2026,9)

The function returns:

0.031

When the Excel cell is formatted as a percentage with one decimal place, the result is displayed as:

3.1%

Return value​

FINPACK.CPIINCREASE returns a numeric ratio rather than formatted text.

For example:

0.031

represents:

3.1%

Because the result remains numeric, it can be used directly in other Excel formulas.

Percentage formatting​

To display the result as a percentage, apply a percentage number format to the Excel cell.

For example:

0.031

displayed using a percentage format with one decimal place becomes:

3.1%

Same month is important​

A 12-month CPI comparison uses the same month in consecutive years.

For example:

September 2026 versus September 2025

is a 12-month comparison.

A comparison such as:

December 2026 versus January 2026

does not represent a 12-month change because the two observations are only 11 months apart.

The U.S. Bureau of Labor Statistics describes 12-month CPI changes using the same month in consecutive years. BLS: Calculating percent changes

CPI Increase versus CPI Average Change​

FINPACK.CPIINCREASE compares two individual monthly CPI observations:

Selected month
versus
Same month one year earlier

FINPACK.CPIAVGCHANGE compares average CPI values over two consecutive periods of equal length.

For example, a 12-month FINPACK.CPIAVGCHANGE calculation ending in September 2026 compares:

Average CPI: October 2025 through September 2026
versus
Average CPI: October 2024 through September 2025

Use FINPACK.CPIINCREASE for the conventional same-month annual CPI change.

Use FINPACK.CPIAVGCHANGE when you want to compare averaged CPI periods.

Estimated observations​

The calculation may use an observation that was not published by the provider but was estimated using the provider's recommended methodology.

FINPACK.CPIINCREASE still returns a numeric result when the required observations are available.

The worksheet function itself does not append an estimated-data label to the cell result.

Use the finPack task pane or CPI history when you need to review estimated-data status.

Errors​

FINPACK.CPIINCREASE returns an Excel error when the requested increase cannot be calculated.

For example, this can occur when:

  • The country is not supported.
  • The CPI series is unavailable.
  • The selected month is outside the available CPI history.
  • The corresponding month from the prior year is unavailable.
  • The month is not between 1 and 12.
  • The BPOpti service cannot provide the requested result.

Excel may display:

#N/A

Internet connection​

FINPACK.CPIINCREASE performs the calculation through BPOpti services and therefore requires an internet connection when Excel calculates the function.

Use CPI Data to view the latest CPI Increase for a selected CPI series.

Use CPI Value when you want a specific monthly CPI value together with the change from the immediately preceding month.