Why a thermometer beats eyeballing it
Thickness, starting temperature, and heat level all affect how a steak looks on the outside at any given doneness, which makes judging by appearance alone unreliable. Checking the internal temperature with a probe thermometer gives a consistent, repeatable result no matter how those other variables shift from one cook to the next.
Carryover cooking means "done" happens after the heat, not on it
Because residual heat keeps cooking a steak for a few minutes after it leaves direct heat, pulling it at the exact target temperature actually overshoots it slightly. Factoring in that 5-9°F (3-5°C) rise — and pulling the steak just under the target — combined with a proper rest afterward, is what actually lands you on the doneness you were aiming for.
Frequently Asked Questions
Can I get accurate results with the finger test alone, without a thermometer?
It can give you a rough sense of doneness, but thickness and differences between individual hands introduce enough error that a probe thermometer is recommended whenever precision matters.
What happens if I skip resting the steak?
Cutting into it immediately releases the juices all at once, leaving the cut surface dry and the texture noticeably tougher. Just 5-10 minutes of resting significantly reduces that juice loss.