The basis for the computations are the monthly consumer price indices from Statistics Norway, see The consumer price index (CPI). Go to "Tables" and Table 1. The Norwegian consumer price index by month. 2015 = 100
Examples of calculations
In use of the indexes for adjustment purposes, sometimes there is a need to calculate the percentage change in the index for a specific period of time.
The following example shows the percentage change from August 2018 to March 2021 for Consumer Price Index:
August 2018: 108.9 (index)
March 2021: 114.6 (index)
Increase in percentage: ((114.6 / 108.9) - 1) * 100 = 5.23
The increase in Consumer Price Index from August 2018 to March 2021is approximately 5.2 percent.
Increase in percentage: 5.2
Amount to be adjusted: NOK 1000
Increase: (1000 * 5.2) / 100 = 52
New amount: NOK 1000 kr + NOK 52 = NOK 1052
Alternative calculation method: 1000 * 114.6 / 108,9 = 1052.34
New amount after adjustment is approximately NOK 1052
In some cases, users need to change the base year. The example below show how we converted from the base index 2015= 100 to the new base index 2020= 100 for the index value per March 2021.
Average 2020: 112.2 (index)
March 2021: 114.6 (index)
Index value per March 2021 with base 2020 = 100 equals: (114,6 / 112.2) * 100 = 102.1