A chalk line apparatus for marking regularly spaced locations. The apparatus comprises a casing for powdered chalk containing a rotatable reel, line wound on said reel, and an exit opening for the line at one end of the holder. The line has evenly spaced short segments disposed thereon so that when the line is tensioned to a predetermined level of about 10-15 lbs, the segments reside at precisely placed predetermined intervals. When the line is snapped, chalk marks are placed on the wall surface in a pattern that identifies the appropriate locations of underlying wall studs.