I'm longer than you! : an epic contest of measurement

"When Blue Whale and Supersaurus hold a contest to see who is longest, desperate measures are called for (or any measures!). Enter Inchworm, who offers to measure them each from tip to tail to determine the winner. Inchworm measures Blue Whale in inches, but has to leave early to prepare for its cocoon. Enter Centipede, who measures Supersaurus in centimetres. But with one measurement in inches and the other in centimetres, how will they ever fig...