The average spoken word per minute for most professionals is about 150 words. As a careful typist, I am comfortable transcribing at about 50 words per minute. If I listen to the entire work again to ensure accuracy, my total time is 4 minutes of work per minute of transcription. Though my transcription itself is completely manual, I also pay for a software that allows me to pause from the keyboard. This is something I take into consideration when pricing this gig. 20 minutes is about 6 pages when completed. If you need accuracy, I'm the lady for the job!