Click the top down arrow to choose the thread type. Unified inch, ISO metric, taper pipe threads are covered. Click the other down arrow and use the drill chart to find the size needed. Click on the line to enter it into the diameter window.

This application opens ready to use the measuring system last used. If the metric system was used last, you'll be prompted to change to "Inch" for inch threads and vice versa. You may also use the “Inch” and “Metric” options to convert values shown between Inch and Metric measurements.