Calculator for Trace Width of Surface Microstrips

As soon as you need to design a PCB with controlled impedance tracks you'll need to calculate the correct trace width for your application.
In order to find the right trace width you can enter your PCB manufacturer's layer stack-up (or choose one from the presets), the required impedance and allowed impedance tolerance.
Please note that all trace width calculations are only approximations since the physics behind it are pretty complicated and exceed the capabilities of practically every calculator. For this reason you'll always need to define an allowed impedance tolerance and choose a trace width within that margin based on what works best in your specific use case.

A Surface Microstrip is a single trace on one of the two outer layers that couples through the dialectric with a ground reference plane.

Illustration:

Source: Digi-Key