Some like to adjust their arrow length to use as a tuning aid for spine rangeand accuracy, shortest isn't always better.

If your looking to just go as short as posible, just nock your arrow, draw it all the way back and make a mark on arrow where it is supported by the arrow rest. Now measure 1 inch in front of that mark and that should be the position to cut your arrows. Most arrow lengths depend on what style arrow rest you have and riser configuration. Before you cut your arrows on that 1 inch forward of mark, verify tht there isenough clearance for your hunting broadhead.