The safe internal temperature to cook chicken breast until it is done is 165°F (74°C), according to USDA guidelines and food safety experts. This temperature ensures harmful bacteria like Salmonella are effectively killed, making the chicken safe to eat. Key points for cooking chicken breast:

• Use a meat thermometer to check the internal temperature in the thickest part of the breast.
• The target internal temperature for doneness and safety is 165°F (74°C).
• Cooking chicken breast to 165°F at typical oven temperatures (350°F to 400°F) usually takes about 20 to 30 minutes, depending on the size and thickness.
• Holding chicken at a slightly lower temperature, like 155°F, for a longer time can also be safe due to time-temperature pasteurization, but 165°F is the standard recommendation.
• Removing chicken promptly once 165°F is reached helps avoid dry meat.

In summary, chicken breast is done and safe to eat when its internal temperature reaches 165°F measured with a meat thermometer.