According to Robert Spence Hardy, the Koran contains "about 6,000 verses, 77,639 words, and 323,015 letters" (Eastern Monachism, page 190). The number of words is usually rounded up, e.g. to 78,000 or even 80,000 (compared to the Bible's 800,000 words).
According to Michael Cook's book The Koran: A Very Short Introduction (chapter 3, emphasis mine),
We hear of medieval copyist who completed a Koran in six days; when he foolishly boasted that 'no weariness touched us' (Q50:38), his hand is said to have withered. Another, more prudent copyist used to take four months.
(Cook also adds that the Islamic world was slow to adopt the printing press: Istanbul didn't adopt printing before the eighteenth century and the Koran printed under Muslim rule was produced in the nineteenth century.)
Copying around 78,000 words in four months or roughly 120 days would require copying around 650 words per day or 65 words per hour (if we can assume a ten-hour workday). That corresponds to just over a word per minute.
If we assume one rest day per week and an eight-hour workday, the scribe would have needed to copy around 690 words per day or around 86 words per hour.
For comparison, John-Paul Flintoff claims that
tests found that the average speed of copying by hand (by adults) is 68 letters per minute (roughly thirteen words). Fast writers manage 113 letters (20 words, not so bad), but slower writers copy at just 26 letters per minute (five words, ouch).
Note that this is based on an unnamed study in Britain, which also found that "one in three people had not written anything by hand for six months".
If both Cook and Flintoff's statements are credible, a scribe copying the Koran worked significantly more slowly than present-day slow writers, presumably not due to a lack of ability but for other reasons: the care needed to avoid errors while copying a holy book and the different writing technologies.
For another comparison, John Lydgate's poem The Fall of Princes is "some 36 thousand lines" long, i.e. roughly six times the length of the Koran if we ignore the number of words per line. Alexandra Gillespie's Print Culture and the Medieval Author tells us that (page 65),
It is estimated that the average London scribe was capable of copying about two pages of continuous prose in textura hand and four–six pages in a more cursive script per day. If this is even approximately right, a single cursive manuscript of a long text such as Lydgate's Fall of Princes (which averages about 180 folio manuscripts leaves of verse) was work for a few months.
"A few months" is vague and possibly the cursive hand Gillespie mentions was a bit faster than what Muslim scribes used, but it still gives the impression that those London scribes were a bit faster than their Muslim counterparts.
Sources
- Cook, Michael: The Koran: A Very Short Introduction. Oxford University Press, 2000.
- Flintoff, John Paul: A Modest Book About How to Make an Adequate Speech. Octopus, 2021. (Google Books's preview does not contain page numbers.)
- Gillespie, Alexandra: Print Culture and the Medieval Author: Chaucer, Lydgate, and Their Books 1473-1557. Oxford University Press, 2006.
- Hardy, Robert Spence:Eastern Monachism: an Account of the Origin, Laws, Discipline, Sacred Writings, Mysterious Rites, Religious Ceremonies, and Present Circumstances, of the Order of Mendicants Founded by Gótama Budha. 1860.
