Predicting the colour of trichromatic prints by measuring the colour of the primaries and their areas has been shown to be possible using large area textile prints. This approach has been extended to paper printing with much smaller coloured areas, in a predetermined array of squares. As before, the light reflected from the coloured areas mixed additively within the integrating sphere of a spectrophotometer. Cyan, magenta, and yellow were used with the addition of red, green, blue, and black, to simulate the typical situation likely to arise in commercial paper ink-jet printers, Partitive colour-mixing theory was used to predict the colours, and the results compared well with those obtained by measurement. However, unwanted overlaps of the printed coloured squares caused all the measured results to be darker and of higher chroma. The reverse process, whereby the area of each colour was calculated for a given target colour, specified by its tristimulus values, was also carried out. The results were generally used to produce the target, within one square out of 16.