(Web) Dynamic text specifications depending on font and text width

I have an order form for printing text to be used as stickers. As seen in the picture, I have options for text input, font, print count and an option to input text width in centimeters, not pixels. Depending on these parameters, I'd need to calculate the text's width and height in centimeters using HTML/JS/PHP and calculate the price used for the materials dynamically. Is there a platform like this maybe or something similar I could use or should I just build it from scratch? Line breaks are included.