Is 70ms 14 or 12% faster than 80ms ? Reading many stackoverflow response, I am still confused. Most answers claimed (1 - 70/80), or 12.5% faster If the math is right, it is impossible to be 100% faster. 10 times faster (1000%) is meaningless (time is negative) I normally avoid using "percentage faster", and prefer ratio: Speed at 80/70 = 1.14X -- https://stackoverflow.com/questions/31506554/is-70-ms-14-or-12-faster-than-80-ms?noredirect=1&lq=1 https://stackoverflow.com/questions/8127862/how-do-you-calculate-how-much-faster-time-x-is-from-time-y-in-terms-of https://math.stackexchange.com/questions/716767/how-to-calculate-the-percentage-of-increase-decrease-with-negative-numbers/716770#716770