The volume increment of a single tree can be estimated in different ways. A problem with some of the methods is that the height increment must be estimated. Strand (1968) worked out formulae that can be used to estimate the form height increment per cent. Tests of one of these formulae were made on data from the National Forest Survey of Norway and from the Norwegian Forest Research Institute. The test on forest survey data indicated rather large differences between computed and observed volume increment. A new formula for the volume increment of Norway spruce is given. Data from 10 permanent sample plots were used. Tests of this new formula gave promising results.