Or stick your pinky in the spark plug hole. It will be at TDC twice (firing & top of exhaust stroke) per crank rotation.

To find the exact TDC, you really need a "stop" which won't damage your piston if you're turning the engine by hand.

70 Roadrunner convt. street car 440+6, NOS, 4-spd, SS springs '96 Mustang GT convt. street car '04 4.6 SOHC, NOS, auto, lowered "Officer, that button is for short on-ramps"