Balcony width
Swags (hook to hook)
Sag depth per swag
Bulb spacing
Lead to the power source
Hook height above floor
Lit string
Bulbs
Hooks
Look for a set of at least
Each swag is modelled as a gentle parabola, which is close to how a light string really hangs. The total adds your lead cable and 10% spare for slack and knots.