Flank Steak Internal Temperature
Beef
Doneness
Rare
49–52 °C120–126 °F
Pull from heat at 46–49 °C115–120 °F
Cool red center, very soft.
Medium rare
54–57 °C129–135 °F
Pull from heat at 51–54 °C124–129 °F
Warm red center, springy. The classic steak doneness.
Medium
60–63 °C140–145 °F
Pull from heat at 57–60 °C135–140 °F
Warm pink center, firm.
Medium well
65–68 °C149–154 °F
Pull from heat at 62–65 °C144–149 °F
Slight pink center, firm.
Well done
71–74 °C160–165 °F
Pull from heat at 68–71 °C154–160 °F
No pink, fully cooked through.
Rest
5 min
Tip
Lean cut — best at medium rare or below. Always slice thin against the grain.
USDA guidance
USDA recommends a minimum internal temperature of 63 °C / 145 °F with a 5-minute rest before serving.
Source
U.S. Department of Agriculture, Food Safety and Inspection Service gives 63 °C145 °F as the safe minimum for this cut.