Why is the second round of toast always darker?

The browning dial is a timer, not a thermostat. It sets how long the elements run, and nothing measures the bread. The toaster is already hot on the second round, so identical time in a warmer machine produces darker toast.

Why it happens

On nearly all toasters the dial is a variable resistor setting the charge time of a capacitor. When the capacitor reaches a threshold, a transistor releases the electromagnet holding the carriage and the toast pops. That circuit knows about elapsed time and nothing else.

Because the housing, the elements and the wire rack all retain heat, the second cycle starts from a much higher baseline. The bread receives the same duration of radiant heat but from hotter surroundings, so it browns further.

A small number of premium toasters do measure the bread — usually by tracking how much moisture has left it — and those genuinely produce consistent results across consecutive rounds. They are the exception.

What to do about it

1. 1Turn the dial down a notch or two for the second round. Most people converge on this by trial and error.
2. 2If you are toasting for several people, letting the toaster cool between rounds works but is slower than simply adjusting the dial.