How do I know how much lighting cable I need to order? Creating a mock up design using string is a common solution. Once you are happy with your design simply measure the string for your required flex length. Leave A Comment Cancel reply Your email address will not be published. Required fields are marked * Comment Name * Email * Denise2020-10-05T14:29:08+01:00 Leave A Comment Cancel replyComment Save my name and email in this browser for the next time I comment.