By Nchetachi Chukwuajah
Nigeria’s inflation rate for all the months in 2025 has been reviewed upward following the December 2025 Consumer Price Index (CPI) methodology review by the National Bureau of Statistics (NBS).
An analysis of the CPI year-on-year data published with the November 2025 report and the revised series released in December 2025 shows that inflation was higher in every single month from January to November 2025 than was previously reported.
The change in the inflation data was not due to fresh price shocks, but from a statistical re-anchoring of the inflation base.
According to the NBS, before December, Nigeria’s year-on-year inflation rates for 2025 were calculated using a single-month reference base under the old 2009 CPI structure.
The NBS noted that using a single-month base would have produced “an artificial spike in the December 2025 year-on-year inflation rate,” driven by base effects rather than underlying price movements.
However, the NBS rebased the CPI in December and adopted a 12-month average reference period for 2024, setting the average CPI for the year to 100.
The bureau noted that retaining the single-month base would have exaggerated year-on-year inflation due to base effects, particularly at the end of 2025.
The NBS further stated that the revised approach aligns Nigeria’s CPI framework with international best practice and improves stability and comparability over time.
According to the NBS, the rebased CPI affects already released year-on-year inflation rates for January to November 2025, prompting a full recalibration of the inflation path.
The revised CPI series shows a consistent upward trajectory across all months of 2025, with the largest gaps appearing earlier in the year and gradually narrowing towards November.
A look at the data showed that in January 2025, inflation previously stood at 24.48 per cent but was revised upward to 27.61 per cent, a difference of 3.13 percentage points.
The rate moved from 23.18 per cent to 26.27 percent in February 2025, representing a 3.09 percentage point increase.
In March, the inflation rate changed from 24.23 per cent to 27.35 per cent, while the rate was revised upwards from 23.71 per cent to 26.82 per cent in April.
The upward trajectory was maintained into May, where inflation rose from 22.97 per cent to 26.06 per cent, and changed from 22.22 per cent to 25.29 per cent in June under the revised methodology.
There was a slight moderation in the rates by mid-year, as the July inflation changed from 21.88 per cent to 24.94 per cent, and moved from 20.12 per cent to 23.14 per cent in August.
The September inflation rate changed from 18.02 per cent to 20.98 per cent, October figures moved from 16.05 per cent to 18.97 per cent, while the November rate, initially reported at 14.45 per cent, was revised sharply upward to 17.33 per cent.
Headline inflation slowed further to 15.15 per cent in December 2025, down from the revised 17.33 per cent in November, reinforcing the downward momentum.
Under the revised CPI methodology, inflation did not decline as quickly as earlier data suggested, as price pressures remained structurally higher for longer across the year.
