How well does modern evidence support Ebbinghaus's forgetting curve?

Very well — a 2015 direct replication reproduced his data almost exactly, with his equations explaining ~98.8% of the variance.

Because Ebbinghaus tested only himself with one method, his curve could have been a quirk. Murre and Dros (2015, published in the journal PLOS ONE) painstakingly repeated his procedure and found their new data closely matched the 1885 original — an unusually strong replication for a 130-year-old finding. One wrinkle: they observed a small "jump up" in retention around the 24-hour mark, consistent with sleep helping to consolidate memory. This is well-replicated science, not a preliminary claim.