Nurse to patient ratio

What is a safe nurse to patient ratio on a medical/surgical floor?
One nurse to 3-4 patients is what i saw in clinicals.
On a regular Med-Surg floor? No tele patients? 1:6 is common. Not sure i would go so far as to call that safe though.
One to 4-6 during the day, up to 8 or 9 at night (no tele). Again, common but.... ? Safe???