Had been wanting to keep this in a handy place! All sizes shown in centimeters.

A F6 canvas in France would measure 41.0 cm by 33.0 cm, where as an F6 canvas in Japan would measure 41.0 cm by 31.8 cm.

Who decides this stuff?

European Japanese Canvas Sizes

Chart showing the difference between European (France) canvas sizes and those you find in Japan