How to convert Longitude and Latitude to XY Coordinates?

Thank you @L1z4rD89 for trying to help me out.

Yes, I need to convert from EPSG:4326 - WGS 84 to EPSG:32630 - WGS 84 / UTM zone 30N

Would you be able to point me to the correct formulas to use? How accurate are those?

Many thanks,
Luigi