“This is the year of the changing hemline,” says this Butterick Fashion News flyer from July, 1970.

“Butterick Goes to All Lengths: This is the year of the changing hemline.” Butterick Fashion News flyer, July 1970.
“There is no longer one length for one woman, but a whole wardrobe of lengths from which to choose. Mini, regular, midi and maxi length. . . Butterick has the right looks in the right lengths.”
Pattern number 5785, on the front cover, is even longer than ankle length.
“Butterick 5785: From head to toe, a full length cover-up; super to sew in see through crochet fabric. Misses 8 to 16, 75 cents.
Other lengths were defined in this chart:

Mini, Short, Regular, Midi, and Maxi skirt lengths, defined in a Butterick Fashion News flyer, July 1970.
However, an even shorter length, the Micro Mini, appeared in the same flyer:
This dress was so short that the pattern included matching bikini briefs. No wonder the girl on the lower right looks shocked.
“Butterick 5821: The micro mini, with self belt, raglan sleeves and matching bikini briefs. Easy. Misses 8 to 16.”
For comparison, here is a mini length wrap dress, which can also be worn as a tunic over pants (both views are shown):

Butterick 5759: mini length wrap dress “can double as a tunic over matching pants with flared legs.” July 1970.
“Butterick 5759: A mini length wrap dress with elasticized waistline, long kimono sleeves, and a narrow self-tie belt can double as a tunic over matching pants with flared legs. Sew And Go. Misses 8-18.”
Some examples of skirt lengths from the 1960s can be seen here. True mini-skirts were not generally worn until the mid-sixties. This Butterick pattern by Mary Quant appeared in October of 1964:

This pattern, No. 3288, by quintessential sixties’ designer Mary Quant, was featured in the Butterick Fashion News flyer for October 1964.
The hem hits just at the bottom of the knee, or slightly above. Over five years later, in 1970, Butterick’s chart still called this “regular” length.