Please remember, the above is only a guide. We would suggest that if in doubt, choose a paddle that is a little longer than you think you may need, you can always shorten the Staff later, but you can't make it longer. The shorter your paddle the more it will strain your back. If it is too long you cannot generate sufficient power in your stroke. You can always ask for the "T" bar handle not to be fixed, you can then easily adjust the shaft length and fix the "T" bar in place with a single rivet once you are comfortable with the paddle length.

Golden Rule:
It is far easier to use a paddle that is a little too long
than it is to use one that is a little too short..!

Paddling styles:
Werner, probably the Worlds largest paddle manufacturer suggests the following:
For Surf Paddling, you should have a paddle about 8" above your your height
For Touring / Cruising, you should have a paddle about 10" above your your height
see below.