147 - 154cm = 100cm
155 - 161cm = 105cm
162 - 168cm = 110cm
169 - 176cm = 115cm
177 - 183cm = 120cm
184 - 195cm = 125cm
196 - 200cm = 130cm
You will still less commonly find different ratios of calculation (e.g 0,68 / 0,66 / 0,76) in Scandinavia and Germany , in Europe but more usually it will be based metrically on height.
To gauge what is right and when your are in between two sizes, go for the longer length to be sure to have enough support.
Standing up , your elbows should be at 90 degrees.
Frédéric Gingreau Personal Trainer on the Côte d'Azur.