- Somebody has no doubt told you this: The best fundraising copy is not higher than the 6th grade reading ease level.
- Someone else has told you Our donors are highly educated, it would be a big mistake to talk down to them by writing at a low grade level.
Statement #1 is correct. Statement #2 is wrong.
The standard way reading ease is measured is the Flesch–Kincaid Grade Level, which applies a calculation to sentence length and number of three-syllable words to come up with a "grade level."
Here's the important thing about reading grade levels: It's not about education. It's about ease of comprehension. Low grade level copy is not "talking down" to educated readers or treating them like children. Think of it instead as a form of courtesy, like enunciating clearly when you talk. The most super-educated PhD. will appreciate and respond to copy that's easy to read.
Copy that's 4th to 6th grade level is barrier-free and can be read quickly and comprehended well by all adult readers. Go much above that and it takes extra concentration. A reader who's in a hurry will have trouble comprehending, and will be more likely to skim or to stop reading. And it just gets worse as the grade level climbs.
Nobody is forced to read your fundraising. If they have to fight to comprehend, they just won't do it. And you'll lose responses as a result.