Egg timers like this one take the guesswork out of cooking eggs to your liking. Instead of setting a timer, you visually see how done your egg is.
https://www.amazon.com/Norpro-Egg-Perfect-Timer/dp/B00004UE75/ref=asc_df_B00004UE75/?tag=hyprod-20&linkCode=df0&hvadid=167142021489&hvpos=&hvnetw=g&hvrand=9518251214647058166&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9031174&hvtargid=pla-262770887278&psc=1