  The sizes of canvases and stretchers for oil painting have been standardized
in France in 19th century and widely accepted in many countries in Europe as
well as in Japan so far. These standard sizes do not follow the golden ratio
and porte d'harmonie number as has been often claimed. In this work, a general
formula is derived to calculate the sizes of painting canvases and stretchers,
which satisfy exactly the golden ratio and the porte d'harmonie number as well
as the rule for optimal use of material in their mass production. Based on this
formula new canvas and stretcher sizes are calculated for all three figure,
landscape and marine formats.
