Stanford's undergraduate and graduate admissions have slightly different translation expectations. Understanding the difference helps you prepare the right level of documentation.
For undergraduates, the translation requirement is more flexible. Stanford accepts translations from an English teacher or school official at the applicant's high school. This is a lower bar than most graduate programs and reflects Stanford's understanding that high school students may not have easy access to professional translation services. However, a professional certified translation also satisfies this requirement and provides a more reliable, complete result.
For graduate applicants, the standard is higher. Translations must come from the educational institution or a professional translation service. They must be literal and complete — no summaries, no paraphrasing. Graduate applications also involve a stronger possibility of post-admission WES evaluation, so having a professional certified translation from the start positions you for both the application and any future evaluation requirement.