Baking chicken in the oven at 400 F takes around 45 minutes but sometimes it may take an hour to an hour and half to fully bake the chicken.
The chicken will be fully cooked when a meat thermometer says the internal temperature of the baked chicken is 165 F or higher.
The chicken will also be done when you see no pink or blood running out of the chicken so if you see any pink or blood then cook it for another 15 to 20 minutes.