This is a simple tool that can help you with finding the right measure, which can be considered to be the basis for logical breakpoints for your website. The ideal measure is defined by many factors, this tool only looks at either letter count or word count, in combination with a font and a language. Here's a live example, and here's a long explanation about the theory.
WebMechanic/International-measure-slider
A simple slider to choose the ideal measure, based on several measure theories, font, and language
JavaScript