Work out interconnect rc delay instantly with clear inputs, formula shown and shareable results.
Distributed RC delay is 0.38 x R x C for a wire, and both R and C are proportional to length, so delay grows with the square of length. Splitting a wire into k segments with repeaters cuts delay by roughly k, which is why long global wires are always buffered.
RC wire delay
delay = 0.38 x R x C; with k equal segments the total falls to roughly 1/k of the unbuffered delay
Because resistance and capacitance each scale linearly with length, so their product — and therefore the delay — scales with length squared.
Enough that the repeater delay equals the segment RC delay. Beyond that, repeater delay and power dominate and total delay rises again.