If a website asks for your private key to generate a PFX, that site technically has the power to impersonate your digital identity. For sensitive production environments, always use local tools:
While JPG is an image format and PFX (PKCS#12) is a digital security container, the "conversion" usually refers to extracting text-based certificate data from an image or using an image as a visual element within a digital signature process. Jpg To Pfx Converter Online - Free
By following this workflow, you can successfully move from a visual image to a functional security credential. If a website asks for your private key
Since no single tool "transmutes" pixels into a cryptographic key, the process involves two distinct stages: you use a PFX converter.
Once you have the certificate text and your private key, you use a PFX converter.