I’m on the board of the American Copy Editors Society (ACES). Besides recognizing outstanding editorial work, offering professional training, and putting on (shameless plug) this month’s national conference in Las Vegas, we also regularly answer questions from working editors like you.
We recently heard from an editorial manager with a problem. “We are constantly criticized for taking too long on projects,” she told us. “Are there statistics for how long industry pros spend per page editing? I have no benchmarks to present in defense of our work.”
ACES board experts hit the books looking for an answer. I knew in my head that “six pages per hour” was a standard metric. Once I started trying to find a definitive source, I was surprised to see how very much in sync all of the guides that I referenced were.
Here’s what a few industry-standard references have to say on the matter:

• The Copyeditor’s Handook, Third Edition, by Amy Einsohn (see pp. 22) – standard rate of 4-7 pages/hour

• Substance and Style: Instruction and Practice in Copyediting, Mary Stoughton (see pp. 58) – standard rate of 6 pages/hour

• The New York Public Library Writer’s Guide to Style and Usage (see pp. 747) – standard rate of 5 pages/hour

• The Chicago Manual of Style, 16th Edition (see pp. 71, section 2.49) – suggested rate of 4-5 pages/hour

• STET Again: More Tricks of the Trade for Publications People, from EEI press (see pp. 295) – standard rate of 6-8 pages/hour

• EFA standard editing rates, at http://the-efa.org/res/rates.php – standard rate of 5-10 pages/hour

This rate assumes standard-quality text and about 250 words per page. Of course, text in bad shape will take longer; text in great shape will go more quickly.
But watch out: While these rates apply to double-spaced copy, most work actually comes in single-spaced. It’s up to editors to do the math for clients and remind them that the rate drops to three pages per hour for single-spaced copy.
So there you have it. I was happy to help a fellow editor with some hard numbers to present to her colleagues (or at least some reference points for her team to work toward). And it was good to confirm for myself that, at least on this point, the editorial sages are more or less in agreement.
Hey, nobody ever said editing was fast work.
Samantha runs Dragonfly Editorial.