1. You need to consider the creepage and clearance distances required for you mains voltage. 2. You also need to work out what current is flowing in that track and then decide what temperature rise above ambient is acceptable for that track.  3. Then use tables or an online calculator to work out what track width you need to stay below that temperature rise.  4. If you cannot accommodate the width then you must either got to 2oz copper or use copper on more layers. For more on creepage and clearance distances see: [https://www.smps.us/pcbtracespacing.html](https://www.smps.us/pcbtracespacing.html) For more on trace width calculations see this topic: [https://easyeda.com/forum/topic/PCB-high-current-thermal-design-562f7a69a7ad41a38b18ea150d6703ed](https://easyeda.com/forum/topic/PCB-high-current-thermal-design-562f7a69a7ad41a38b18ea150d6703ed)

Not sure if this is of any use [https://www.4pcb.com/trace-width-calculator.html](https://www.4pcb.com/trace-width-calculator.html)