How do I determine what size trek pole I need?
Hold your elbows to your side and extend your forearm straight out horizontal to the ground. Measure from your hand to the ground. You want your pole to be about that length. If you measure in inches, you may need to convert to metric since most poles heights are listed in metric. There are free on-line converters. Some poles are adjustable, which enables you to get the height exactly right for you, and to adjust up or down if you are going uphill or downhill for an extended time (shorter for uphill, taller for downhill). Pick the range that includes your measurement. I have adjustable poles and I love them.
Stand with your elbows next to your body, arms at a 90-degree angle. Hold a tape measure in one hand and measure the distance from your fist to the floor. That's roughly the length of pole you will need. (I am 5'4" and use 98cm poles). These Black Diamond Distance FL poles easily adjust, so all you need to know before ordering is which size range you need (95-110cm or 105-125cm), and then you can adjust them to the length that's most comfortable for you. BTW, I *love* my Black Diamond Distance FL poles! Unlike most other brands, they break down and fold up easily so they will fit in a suitcase.
You want your elbow to be at a 90 degree angle when you are holding the poles. Therefore, the top of the handle should be about at your waist. When you are going uphill you may want the poles shorter and going downhill, longer. I usually adjust mine about 10 cm either way. There are other considerations, though, about type of pole, weight, etc. Hope this answers your question.
I bought the Black Diamond 105-120 cm poles and I am 5'4". They are perfect for me.
Click on the size chart on black diamond website (sorry doesn't let me include the link) - shows which poles match your height. But basically you want to be able to have arm out at 90 degrees and measure that height.